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Soldering Tips For Lead-Free Solder




The days of using a 20 watt soldering iron from Radio Shack are long gone when it comes to repairing lead free soldered circuits in Apple Computers, PCs, and other lead-free electronics equipment. With multilayer boards, thick ground planes and power planes, and high temperature circuit board materials, along with countries having bans on the [...]






Click to read more about: Soldering Tips For Lead-Free Solder

The days of using a 20 watt soldering iron from Radio Shack are long gone when it comes to repairing lead free soldered circuits in Apple Computers, PCs, and other lead-free electronics equipment.

With multilayer boards, thick ground planes and power planes, and high temperature circuit board materials, along with countries having bans on the use of leaded solder in circuit boards; electronic components are now being attached using lead-free wave soldering or pick-and-place machines using conductive epoxy flux adhesives and then heat cured. All of this adds up to quite a bit of difficulty in reworking and repairing circuit boards today.

CHIPQUIK at JWestSales.com While it is good to keep our environment clean, I think the wide spread use of lead-free solder in printed circuit board assembly processes is a case filled with a manufacturing life of unintended consequences. There are major challenges that have and continue to affect printed circuit board manufacturing around the world. First off, PCB materials must be able to withstand lead-free soldering temperatures of up to 260[degrees]C during the assembly operation. [1] This in itself, requires the use of more expensive, and much more difficult materials to work with at the PCB manufacturing stages. Not only is the multilayer construction much more difficult to deal with, but the drilling of the holes in thick multilayer circuit boards, with circuit board materials that are of a “harder” material nature, as compared to traditional FR-4 resin systems (not designed for lead-free), directly adds to the manufacturing costs involved.

I also find it interesting, that about the time where the world (pushed by the European Union) started converting over to using lead-free PCB manufacturing techniques, there seems to be a correlation between the electrolytic capacitor failures that started to occur a short time later in TVs, Set-Top Boxes, Computers, PCs from Dell, Apple, and other computer manufacturers, along with a host of other high powered electronic gadgets. I have no way of proving it, but I suspect that many of these components were hit with a large temperature blast through either high temperature wave soldering processes or oven based curing used in the finished component filled PCB assemblies.

“With a melting point of 217°C, SAC solder also is closest in melting point to the conventional lead–tin solder. This does mean, however, a yet-unquantified increase in energy use. Furthermore, the higher temperature may pose problems for the electronics industry. Higher temperatures mean more stress on components and the entire manufacturing process, notes Geibig. Higher temperatures also mean increases in the time it takes to make products, because more time is required to heat and cool the products during the course of their manufacture.” [2]

On July 1, 2006 the European Union Waste Electrical and Electronic Equipment Directive (WEEE) and Restriction of Hazardous Substances Directive (RoHS) came into effect, prohibiting the intentional addition of lead to most consumer electronics produced in the EU. California recently adopted a RoHS law and China has a version as well. [3] In order to meet the new directives established by the EU on removing the lead from electronics, has greatly affected the PCB assembly world at large. In effect, countries that did not have directives for the use of lead-free electronics assembly, were forced by default of having to build to meet the international requirements from the EU.

“This directive (EU Directive 2002/95/EC) places a restriction on the use of certain hazardous substances in electrical or electronic equipment sold or used in the European Union (EU) after July 1, 2006 with some exemptions.” [4]

‘Within the United States, California’s Electronic Waste Recycling Act imposes a fee on “covered electronic devices” currently being sold within the state. This fee is intended to cover the cost of properly disposing of the products when they become waste. Second, it requires “covered electronic devices” sold in California after January 1, 2007 to meet the same requirements as those found in European Union Restriction of Hazardous Substances (RoHS) legislation. Electronic devices containing toxic metals and not complying may not be manufactured, sold, or imported into California after January 1, 2007.’ [4] Other states have enacted similar laws.

So, what does that mean for circuit board and electronics repair folks today looking for ways to extend the service lives of their equipment? Well, there are some special soldering techniques that are involved to do the electronic repair jobs right.

What is required to repair lead-free circuit boards with large discrete components?

These lead-free soldering tips are specifically geared toward the large discrete components such as: electrolytic capacitors, transistors, diodes, bridge rectifiers, and coils (inductor chokes). Information on how to repair and replace surface mount devices with lead-free soldering techniques is waiting for a later date to be written.

1. The minimum wattage for a soldering iron needs to be 60 watts. The 60 watts rating is only part of the specification to consider. Be aware that some soldering irons actually get hotter than others given the same wattage ratings. Additionally, you will need to consider using a proper soldering tip for the job at hand. If you are trying to solder on a thick multilayer PCB, then a wide tip is absolutely required to do the job right. There is also a difference in the coatings between the lead-free tips and the old standard Pb tips used for the standard 60/40 Tin Lead (60/40 Sn/Pb) Solder. 60/40 Sn/Pb melts at 370 °F or 188 °C while various lead-free solders used in PCB assembly have a melting point range of 415-441 °F or 213-227 °C . It is important to note that the increase in the melting temperature for lead-free solder, does not tell the whole story for proper solder joints involved with component replacements and PCB repairs.

You might be thinking, that the soldering iron I will be using gets up to 850 °F, I should be able to repair any lead-free soldered component on any PCB. That is wrong thinking here. I mentioned at the beginning about having a wide tip when soldering a thick multilayer. But, you need more than a wide tip. The soldering iron, at the tip, must be able to quickly recover on the heat cycle. It must also be able to supply the heat continually at a constant temperature, or near constant temperature to do the job right. This is where the wattage of the soldering iron is a factor for delivering the heat continually.

A thick multilayer PCB acts like a huge heatsink, sucking the heat away from the area that you want it, and dissipating it over the area where it is not required. If you use a small caliber soldering iron to try and remove components on this type of PCB, you will more than likely simply heat up the circuit board in a wide area, including the component itself before the solder will ever melt. In fact, it is quite likely that the lead-free solder will never melt, because the soldering iron can not quickly and effectively localize the heat in a high enough concentration to do any good. Actually you will probably do more harm than good.

I have heard from some folks, and talking from experience, that you will end up throwing a few choice words around that will not endear yourself to your spouse, if you try to use a low powered soldering iron. Even if you do manage to remove the component, the new component you install will have either the poorest of a solder joint, making you look like an amateur, or worse, an overly heated and damaged component that will result in early failure. Solder joints made with a low wattage soldering iron will likely result in cold solder joints, which will result in poor electrical connectivity and a non-working circuit board.

How about a portable butane powered soldering iron, won’t that work better? Been there and done that. Take it from experience, the answer to that question is no. I tried a wide tipped butane powered soldering iron and I was not able to even make a dent in the lead-free solder on a Apple iMac G5 motherboard.

What about a soldering gun? Once again, been there, done that. It doesn’t work with even the highest powered soldering gun. Soldering guns are not really designed for circuit board repairs. Take it from experience, put this idea out of your mind, it won’t work.

So Jim, what do you recommend in a soldering iron? Do you recommend a lead free soldering iron or a lead free soldering station? Let me first say here, that I have recommended some soldering irons and soldering stations to folks that have written to me and asked for my advice on various Apple repairs, and I would be more than happy to recommend something if you send me an email request. I will say this, that you can get a very good one at a very decent price. You don’t have to spend hundreds of dollars on a soldering station. However, don’t make the mistake and think you can get by with the old hobby soldering iron that you have in the desk drawer. Trying to use a substandard, low wattage soldering iron for lead-free motherboard repairs will give you headaches galore.  Actually, I would like to hear more from readers of what you have used for lead free soldering.

2. What is the best way to remove the electronic component such as a electrolytic capacitor off a thick multilayer PCB once I have a good soldering iron or soldering station? I suggest you have the PCB standing up on edge, so that you can work from both sides of the circuit board. Check out the Chip Quik kit for removing the capacitors in difficult circuit boards. While heating up one leg of a radial electrolytic capacitor from the bottom, and at the same time slightly pushing the capacitor from the top, away from the leg being heated, at which time the solder starts to melt, the capacitor leg will start to move out of the hole. Do this for the other leg, alternating back and forth to each leg, and slowly work out the capacitor from the hole as the solder melts. After the capacitor is removed, a solder sucker can be used to remove a lot of the excess solder in and around the circuit pad. Using solder wick, (also referred to as desoldering wick or desoldering braid) on the thicker boards does not work well because of the extra heatsinking that occurs when the solder wick is applied. At this stage of the component replacement repair, invariably, not all the solder will come out of the holes with the use of a good quality solder sucker. This is where I suggest using my next soldering tip.

3. Try using a sewing pin, with a plastic head, (even a correct size safety pin works) and heat up the tip and the solder pad at the same time, once the caps are removed. This will push the solder out of the holes and solder will not stick to the steel sewing pins. Stop in at your local sewing machine center and you will find a large assortment of sewing pin sizes. Select a sewing pin size that matches up to the size of the leg of the capacitor. Once the pin is pushed through the hole, continue to apply heat to the pin and the pad, and move it in and out, making the hole the right size for your new components.

4. Is it best to use lead-free solder when installing the replacement capacitors? I have mixed thoughts on this. On the one hand, since the board is already using a lead-free solder, I would say stay with using lead-free solder. Yes, standard 60/40 lead solder is much easier to work with, due to its lower melting point, and some folks say it seems to work fine, but I have some reservations about using it. One negative item to be aware of here is that it is much more likely to end up getting cold solder joints when mixing solder types, and the other concern is, there may be a reduction in the soldering iron tip life if using the special plated tips designed for lead-free soldering, and using leaded solder.

I do have one major item that must be adhered to; only use a rosin core type of solder. Do not use acid flux. No acid flux. Acid core solder and acid flux will damage the circuit board and/or the components. With that being said, it is important that what ever solder is used, that the old solder and the new solder join (melt) together when installing the new components. Be careful with this that you don’t under heat or over heat your work. Just the right amount will do. It is hard to describe how much, and how long the heat should be applied to get a good solder joint. Take a close look at your solder joints. If they seem to be loose, then reapply the heat until the old and the new become one. As an additional note, and I have to say once again as a matter of importance, remember that the components themselves do not like it too hot for too long.

NC600 Lead Free Solder No_Clean Flux Core To properly solder motherboard capacitors on thick MOBs, you will need to operate the soldering iron or soldering station temperatures at or near maximum temperature settings. Heat up the pad on the bottom first and foremost by having most of the soldering tip on the pad; while at the same time having the tip touch the capacitor leg. I strongly suggest using lead free rosin core solder with a no clean residue; which you can purchase with your capacitors order at www.jwestsales.com. The no clean flux rosin core solder simply means that the center of the solder has a flux rosin core that is activated by heat, and the remaining residual flux does not need to be cleaned off the circuit board and will not harm the onboard circuitry. Remember also, that the MOB has residual lead free solder already present on the circuit pad and lining the circuit board hole walls, and must be melted (typically referred to as “wetting” action) with the new solder to form a good solder joint. If you use standard 60/40 lead solder for soldering, it is much more difficult to do the job just right, and is much more likely to produce cold solder joints because the different types of solders melt at substantially different temperatures and will not properly join together.

Be careful of other small components and surface mount devices (SMD) on the bottom and top of the boards. These devices are so small, that many times they can be damaged or unattached to the PCB simply by accidentally placing the soldering iron tip on the surface mounted component soldered leads, either moving it or bridging the leads with solder. So what I am saying is, try to use a steady hand.

The picture above, of the custom circuit board clamping hands-free support system, is the brainchild of Paul N. — Grayslake, IL. Paul writes, “You can buy a 12″ x 2.5″ (depth) wood-working clamp from Home Depot for about $10 and a 3″ ‘C’ clamp for another $5. Then apply some adhesive-backed, dense foam rubber on each face of the wood-working clamp. Note that I removed the hard rubber covers that were on the clamp originally.” Paul calls the device the, “Kludged Circuit Board Clamp.” It is important to note that when clamping the circuit board with any clamping device, that you do not position the clamps on top of any components or the very small low profile SMDs on either side of the PCB.

There is another lead free soldering/unsoldering components helper that is simply amazing! Check out the video of the Chip Quik lead-free unsoldering kit and system of replacing components on circuit boards. I highly recommend this patented SMD and discrete components removal kit.

Read more about Apple iMac G5 Motherboard and Apple Power Supply Repairs.

Feel free to contact me at anytime.

Jim Warholic

Years of experience in the electronics industry. :-)

Sources:
[1] The effects of lead-free on PCB fabrication: assemblers may bear most of the brunt of the…

[2] Getting the Lead Out of Electronics

[3] Solder: Wikipedia

[4] Why Should I Care About RoHS and Lead-Free Initiatives?

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Apple iMac G5 Power Supply Issues and DIY Apple Repairs




Please help bring my beautiful Apple G5 back to life. High quality, low ESR, capacitors for sale, or match iMac PSU model type you have to the detailed pictures. Purchase high quality, low ESR, mother board grade, long life, high temperature rated capacitors for your iMac G5 PowerPC mother boards. Are you having problems with [...]






Click to read more about: Apple iMac G5 Power Supply Issues and DIY Apple Repairs

Please help bring my beautiful Apple G5 back to life.

High quality, low ESR, capacitors for sale, or match iMac PSU model type you have to the detailed pictures. Purchase high quality, low ESR, mother board grade, long life, high temperature rated capacitors for your iMac G5 PowerPC mother boards.

Apple Capacitors For Sale - Click Here

Are you having problems with your Apple iMac G5 17 and 20 inch consumer, university, or student models? Does your iMac turn off by itself? Are you seeing strange graphics on the video screen? Is it to the point where it doesn’t even turn on anymore? Is it running hot and the fans sound like a vacuum cleaner?

Well folks, here is one of the problems with many of the Apple power supplies manufactured for their iMac G5, 17 and 20 inch series computers. But fear not, I have put a “How to Fix Series” together on how to fix an iMac G5 power supply and mother board. Power supply information is located right here in this article. I would also suggest reading the latest article on Fat Caps and Ripple Current to have a better understanding of what is happening with Bad Caps inside these Apple iMac G5 power supplies and logic cards.

Also, you can read and see how to fix the G5 mother board over here.

If your Apple iMac G5 power supply doesn’t match up exactly to what you see pictured below, feel free to send me your pictures (inside and outside of the iMac MOBs and PSUs). I also have provided additional pictures for comparing which PSU capacitor kits are available for the various power supplies over at “Inside the Apple iMac“. You can also click the buy now buttons to purchase the power supply kits.

As a side note, if you need to get the data quickly (pictures, files, and programs) off the HD for your old Mac, and place it on your HD on the new Mac, read about the Apple iMac G5 Hard Drive Data Recovery. It is designed for those that want to recover the information from their hard drives on a dead PC or Mac. This HD device works really great for Apple iMac backups too!

Apple iMac G5 Power Supply 17 Inch Model

Apple iMac G5 Power Supply 17 Inch Model
180W – Apple P/N 614-0293

Figure #1

Updated 9/12/09: High Quality Low ESR capacitors, computer motherboard grade, 105ºC, 10mm X 16mm, now available for sale in kit form for the Apple iMac G5 computer MOBs and the PSUs.

The capacitor sizes, included in the MOB kits, are the actual original sizes of the capacitors on the motherboard; making your job much easier to replace them. They are the perfect fit for both diameter and height. Note: The PSU cap kits have been upgraded.

International shipping is available for many countries. If your country isn’t listed for a shipping destination, please let me know to add your country to the list. Please provide your full name (first and last name) when ordering capacitors. Read the Shipping for shipping and delivery information.

If you are interested in more than 10 MOB cap kits, please send me an email with a total amount of how many iMac G5 cap kits you are looking for, along with a note of which of the two different cap kit sets you are interested in. Note: Apple early model and late model iMac G5s with the PowerPC processor have different quantities of caps required on the MOB. Click the eCommerce link. Capacitor information is provided there. Verify what capacitors your Apple iMac needs, and bring your iMac G5 back to life today.

Send me an email with your questions, or special order requests. I now have all the power supply cap kits available. Feel free to contact me any time, with any questions. Take a look at the PSU cap kits that are available for purchase.

Just a brief update for those that have been out of the capacitor loop. About the time Apple was building their G5 line of personal computers, several Taiwanese electrolyte manufacturers began using a stolen electrolyte formula that was incomplete, and lacked key ingredients needed to produce a stable capacitor. The missing ingredients caused the electrolyte in the capacitors to break down, evaporate, leak out of the cap casings, caused overheating of the capacitors themselves under normal load conditions, and subsequently caused exploding poppers. Consequently the capacitors started bulging, overheating, and exploding in many of the power supplies and mother boards manufactured by Apple, Dell, Hewlett-Packard, and others which has been documented by numerous articles online. In fact, Dell took a “$300 million financial charge on its earnings to cover costs associated with the replacement of motherboards with faulty capacitors in some of its Optiplex workstations” in late 2005 early 2006. For those of you that are interested, I have documented a do-it-yourself repair procedure and an educational information manual on the Apple iMac G5 motherboards along with students’ user comments.

Note: Apple provided an iMac G5 Repair Extension Program for Video and Power Issues: See the frequently asked questions section at Apple about which models and serial numbers are/were covered. Howeve
r, in all likelihood (“As of December 15, 2008, this program is now closed.”), the iMac G5 Repair Extension Program has run out its course for most, if not all iMac G5 PowerPC owners. See Apple information on the power supply and the video and power issues documents. You can read the actual repair extension program text in the Apple iMac Mother Board article, exactly as it was in the original Apple documents. The program was available for certain iMac G5 PowerPC models that were sold between approximately September 2004 and June 2005 featuring 17-inch and 20-inch displays with 1.6GHz and 1.8GHz G5 processors. You may also go to any Apple Retail Store with a Genus Bar and have the Apple folks take a look at your iMac for you. Find the nearest Apple Retail Store – Genius Bar in your area, and even make an Genius Bar appointment online too. Apple provides technical support for your Mac, iPod, Apple TV, and iPhone at the Genius Bar too.

Identifying the Apple iMac Power Supply Problem or iMac G5 Motherboard Problem

Apple provides a diagnostic guide for determining whether the problem is with the motherboard or the power supply. See the following link to the: iMac G5: Troubleshooting when your computer won’t turn on. Included in that Apple document are instructions of how to turn on an iMac with the back cover off. There are two small buttons located under the fan cover as displayed in the document. One button is the internal power button, and the other button is for resetting the System Management Unit (SMU) which is located right next to the internal power button. “Note: If you’re using an iMac G5 (Ambient Light Sensor) computer, your SMU was already reset when you unplugged and replugged the computer. You won’t see an SMU reset button to press, and that’s OK, as this action has already been done. (If you aren’t sure which iMac G5 model you have, click here for help.)” Source: Apple

Since, I feel that I have been somewhat of an online trailblazer on documenting the iMac issues and the Apple iMac G5 motherboard repairs project, I thought I would take the time to dive into another area that many of our readers have stated is also a big problem with the Apple G5 line of computers. That big issue has to do with the main power supply installed in the iMacs are dying and dropping like flies. From what I understand (though not confirmed) about the iMac PSUs, is there are at least several different power supplies used by Apple in their iMac G5 model lines. The part numbers are located on the back of the PSU case. This power supply is Apple P/N 614-0293 Rev. A 180W. The serial number has a barcode graph. The various models associated with this particular DIY repair document are for Apple: iMac G5 (20-Inch), iMac G5 (20-Inch iSight), iMac G5 (17-Inch), iMac G5 (17-Inch iSight), iMac G5 ALS (17-Inch), and iMac G5 ALS (20-Inch) consumer, university, and student models. See the Apple Power Supply, 17-inch Replacement Instructions for how to remove and install your power supply unit. If you have an Apple model with the ambient light sensor, pay particular attention to not breaking the wiring or the sensor that is mounted to the lower portion of the power supply when removing the PSU. Ok, that gets your power supply unit out. Now what?

There are several service repair or replacement options available for your iMac G5 power supply.

  1. Order a new power supply from Apple Parts & Services.
  2. Order a new PSU, rebuilt power supply, or have your PSU repaired from an outside source.
  3. Repair the power supply unit yourself.

Before I talk about option number three, I would like to point out that when you buy a used or new power supply from Apple or another vendor, you have no idea whether the capacitors that are used in this new or used PS are any better than the ones that were installed in your particular iMac. In all likelihood, the new or rebuilt PSU might not last either. I have heard stories of Apple Service replacing a person’s iMac power supply, and several months later having to do it again. With that being said, it seems obvious that you are taking a chance no matter what you do. By-the-way, the cost of a power supply for an iMac will likely set you back 150 to 200 buckaroos. To me, $150.00 or $200.00 seems like an awful lot of money to shell out for such a small power supply that might not last more than a few months. Capacitors actually get old just sitting on the shelf.

 

Apple iMac G5 17 Inch Model

Apple iMac G5 17 Inch
Figure #2

With many of my readers sharing their iMac G5 stories, both in the online comments section and sending emails to me documenting their problems they are having with their Apple iMacs, I thought it was prudent to take the next step and see if I could discover first hand what was going on in the field with these 17 inch iMacs. I already own an Apple iMac 20 inch model but I needed a 17 inch one for further investigative work. So, I went searching for a broken iMac G5 computer that I could get my hands on for a fair price. I didn’t want to spend a ton of money on a broken Apple to do my research, but I needed to do some more engineering and technical failure analysis of the problems of iMacs not turning on because of mother board problems or a power supply situation. Many people kept telling me that they had an iMac G5 17 inch model computer with no physical signs of bad capacitors on the motherboard. I wanted to verify this for myself. I found an iMac G5 17 inch on Craigslist from a guy that felt he got ripped off by someone selling a supposedly good working iMac to him a short time back and then when he plugged it in, it didn’t work. He took it to the local Apple Genius Bar folks and they said he needed a new motherboard. So, after talking with the seller and asking him some questions about this particular iMac, we settled on a fair price, I met him in San Ramon, CA, and purchased it from him. In my opinion he was a straight shooter, and was nice enough to allow me to open the back cover up before I purchased it in order to make sure all the hardware was inside, i.e., hard drive, motherboard, power supply, fans, memory, cd/dvd SuperDrive. However, he had given away the keyboard, mouse, and the software to some friends. Oh well, keyboards and mice are not very expensive, and if I need Mac OS X software, I can purchase that too.

So, I get my new, broken, what an oxymoron, iMac G5 back to the office and I plug it in, push the power button, and it just sits there staring at me with a blank screen. Nothing powers up. Dead in the water. Dead on arrival. DOA, just what I wanted. Really! Yes, it was time to go to start my engineering class work. I opened the back of the computer once again and took a much closer inspection of the motherboard and the capacitors. Believe it or not, all the capacitors look good on the MOB, just like some of my readers have documented with their own stories in written emails I received from them. This is a completely different issue than what I saw on my iMac G5 20 inch motherboard problem with the bad capacitors on the MOB, with some caps just about ready to pop. All the capacitors on this motherboard looked completely intact, with no signs of swelling, bulging, or electrolytic juice leaking out anywhere to be seen on this 17 inch model.

The next step in my troubleshooting analysis probe was to remove the power supply and do the smell test. Yes, use your other senses other than eyesight when troubleshooting electronics or checking out other industrial equipment. The smell of burnt electronic components can sometimes be detected months and years later, even after a burnt component has been replaced. I placed the power supply up to my nose, and I thought I got a slight whiff of that unforgettable smell of burnt electronic components. Now, it was time for the 20/20 vision eyesight test.

Danger High Voltage Electrical Shock Warning!

This information is provided as a safety precaution and to be careful. A warning at this next stage of the technical analysis is warranted. Electronics, and power supplies in general have high power electronic circuits which can cause a body harm if you touch the wrong thing, even if unplugged. First off, make sure your power supply is not plugged into the AC power outlet. Note also that power supplies typically have a primary high voltage input side and a secondary low voltage(s) output side. The high voltage input side can have large filtering capacitors which can store an electrical charge (DC voltage potential) for a long time, even after a power supply is unplugged from the AC power outlet. Take the precautionary step, and discharge these primary capacitors (after it is unplugged from the AC power) with a screwdriver or place jumper wires across the leads prior to working on the PSU printed circuit board. If you have a different type of supply than what is shown here, with large cylinder capacitors standing up on the primary side, you will not be able to get to the leads on the bottom of the circuit board in order to discharge them. However, if a power supply is left off, unplugged for a period of time; certainly if it has been off and unplugged for an hour or two, the majority of the charge will have dissipated from the capacitors due to in circuit resistance and time.

The iMac G5 PSU case design, is one by which Apple’s engineers designed their power supply units with security torx fasteners (screws) attaching the metal cover housing to prevent unauthorized disassembly, and also I am sure to prevent anyone from getting hurt. I do not own one of these security torx drivers, as I suspect most people can say they don’t have one in their tool box either. I was having an email conversation over the past week with a physics professor at a university. He mentioned he has ten 1.6GHz 17″ G5 iMacs at the university, four of which have already collapsed completely. He was also the first to mention to me, about the security torx key being required to open the PS cases.

In this case no problem on the mother board, but big trouble in the power supply (lots of caps in trouble, one totally blown). One can see some of them through the power supply case, so you might want to take a look at yours.

Be careful of the two high capacity capacitors in the unit, they can be lethal. Ph.D., ARCS

I was able to unscrew the torx screws using a precision miniature screwdriver, and broke out the small internal security tabs within the head of the torx screws themselves. Once I did that, the torx screws were relatively easy to remove.

Pictured Below Are The Electronic Components and Printed Circuit Board Completely Removed From The Power Supply Unit

Apple iMac G5 PSU Capacitors Locations

Capacitors’ Locations, Sizes, and Electrical Values For Apple iMac G5 Power Supply Unit Diagram Schematic.
Click image for close up view of G5 PSU capacitors.
Figure #3

Here’s a confirmed list of the secondary (low voltage) side PSU capacitors installed in the iMac G5 17 inch model. It maybe different on the iMac G5 20 inch, ALS, and iSight models. Please send me an email confirmation or comment on the iSight models, iMac G5 20 inch models, and ALS (Automatic Light Sensor) models, along with any capacitor sizes, quantities, and values would be much appreciated. Please include the Apple p/n and the last four digits of the Apple EEE Code (The last four digits on the serial number). See Cap Note:

  • 3x- 1000uf 6.3V 8mm x 16mm
  • 2x- 2200uf 10V 10mm x 24mm
  • 1x- 1200uf 16V 10mm x 24mm
  • 1x- 4700uf 6.3V 10mm x 30mm
  • 1x- 1000uf 35V 12.5mm x 20mm
  • 1x- 330uf 35V 10mm x 20mm

What you are looking at in figure #3, once you remove the cover of the PSU, are signs of bad capacitors all over the printed circuit board. The first image (Figure #1) above shows the blown capacitor, burnt on the top, and burnt residue on the cover too. If you look closely at Figure #3 and Figure #4, you can see telltale signs of capacitors that are bulging and getting ready to blow their tops. Note the gray silicon rubber adhesive that has been squeezed into and between the electronic components on the circuit board. Some believe that this goop was used for anti-vibration and noise dampening as can be seen with the application of a small amount of goop on a potentiometer adjustment located in the top middle of the PCB, next to the transformers. I can understand the use of it to hold the large primary capacitors in place. However, in my opinion, I believe this was an attempt by the manufacturer (Apple) to make it more difficult to repair the PSUs when using it so liberally throughout the entire PSU. If however, I am wrong, and this is not the case, and the designer intended this goop to be used for anti-vibration noise dampening purposes, the assemblers seem to have gone overboard on their use of it, and it has had an unintended consequence of heat build up. If you look closely at the tall boy cap, I think this one ended up sandwiched in an oven, right next to the coil choke (see closeup picture on Figure #4). In my opinion, it’s not like the small capacitors are going to move once they are soldered in place. It’s also likely that this silicon rubber filler was instrumental in the early failure of the other capacitors too. Excessive heat buildup likely resulted from the insulating characteristics of silicon rubber encapsulation which would result in a runaway thermal chain reaction and cooked the components. Cool air circulation was none existent in these encapsulated areas of the PSU. This silicon adhesive must be gingerly picked at and cut away, in order to get proper access to all the bad capacitors, and be able to remove them when they are unsoldered from the PCB.

Directly below in Figure #4 is a slightly angled picture view, with a closeup of the capacitors on the iMac G5 Power Supply printed circuit board in view and most of the silicon rubber goop removed.

Closeup View iMac G5 Power Supply Printed Circuit Board

Closeup View of Apple iMac G5 Power Supply Printed Circuit Board With Bad Capacitors
Click image for an even closer view of the PCB and PSU capacitors.
Figure #4

The tools I used on the PCB for cutting and picking away at the silicon adhesive are on display in Figure #4 too. I used by trusty precision miniature screwdriver (Husky model HD-74501 S “a gift”) with multiple bits in the handle, which came in handy for removing the torx fasteners and picking away at the small sections of silicon adhesive, the small retractable utility knife box cutter was used to cut away the big gobs of silicon rubber, and the inch/metric 6 inch scale was used for measuring the capacitor physical sizes.

So, the bottom line is most of the secondary low voltage side capacitors must be replaced on this particular G5 PSU. I will probably replace them all. Some of the capacitors I am told are difficult to find. This is especially true of some of the smaller diameter capacitors. Spaces are limited on the PCB. Also, note the one 350 microfarad 35 volt 10mm x 20mm capacitor (Figure #4 with close up view) that is located under the copper heat sink in the middle of the PCB. This is going to be most certainly problematic for capacitor replacement, since it is most likely that I will have to remove the 1000 microfarad cap in front of this 350uf capacitor in order to slide it out from underneath the heat sink assembly. The heat sink assembly is mounted to what appears to be voltage regulators that are impossible to remove without first removing other inductor choke coils, capacitors, and other components in front of the heat sink assembly.

Surface Mount Technology SMT SMC SMD
Surface Mount Technology – SMT
Surface Mount Components – SMC
Surface Mount Devices – SMD
Figure #5

A word of caution about the bottom surface of the PCB before you proceed with on-board capacitor replacements. Be careful not to damage any of the SMC, Surface Mount Components (Figure #5 pictured on the right) located on the bottom of the printed circuit board. These discrete SMT, Surface Mount Technology micro components are very small (some of the SMD, Surface Mount Devices, are hard to see with the naked eye) and consist of SMC diodes, SMC resistors, SMC capacitors, SMC transistors, and SMC IC chips in close proximity to where the large electrolytic capacitor leads protrude through the bottom and are soldered to the plated through holes of the PCB. Be extremely careful when soldering next to these SMDs. If you heat up a SMD by accident with the soldering iron, (see lead-free soldering tips for more soldering information) you will potentially dislodge it from its PCB pad. Figure #3 shows the PCB top side surface before picture, with all the silicon rubber adhesive stuck between the electronic components. Figure #4 picture is after the silicon rubber, for the most part, has been removed from the components on the secondary side of the PSU.

Now, the next step in the process is to purchase the nine electrolytic, radial leads, low ESR capacitors designed for tight spaces. For most folks out there in Internet land, I realize there probably is much technical information to digest here in one quick reading. I feel like I have written and photographed a technical documentary. I will most likely publish an updated technical article or add to this document when I locate new capacitors and proceed with the the installation of these new low ESR electrolytic capacitors. Cap Note: I suspect I will have some different suggested sizes to use for cap substitutes. You are free to print out this document using the “print button” for your personal use, but you are not granted permission to distribute or publish it anywhere else without my prior approval. That goes ditto for all the articles published on this website too.

All information provided here is for instructional purposes only. Please note that I cannot be held responsible for any damage that you might do to your computer or yourself. This website is for educational purposes only and you are responsible for everything you do with the given information. You are responsible for the health and welfare of your own body and computer.

I hope this iMac repair training course series of articles helps everyone that is facing a decision of possibly having to go to the precious and non-ferrous metal reclamation and computer electronics recycle center with their crippled or broken down Apple iMac now and in the future. After all, I believe that these Apple G5 iMacs are not an EWaste product, and are most precious and beautiful machines for their owners to use. I think there is a lot of life left in these very powerful iMac G5 computer machines for today and tomorrow. At least I have a documented road map and general circuit diagram schematic of the main power supply components, along with engineering failure analysis that I will be using myself for technical reference for now and in the future. By-the-way, I now have a large quantity of high quality, low ESR, electrolytic capacitors available for sale for the DIY Apple iMac G5 motherboard repairs. See motherboard repair posting for quantities required. Or, you can order directly from my online store at Out West Sales today.

Power Supply iMac 20 Inch Model Apple Part Number — Apple p/n: 614-0326

Capacitor List and Diameter Sizes For Power Supply Apple iMac 20 Inch

Click this iMac 20” PSU Super Close-up View or Picture Above for Close-up View
  • 330uf    35v    10mm
  • 1200uf   16v    10mm
  • 3300uf   10v    10mm
  • 2200uf   10v    10mm
  • 1000uf   25v    10mm
  • 1000uf   10v    8mm
  • 120uf    50v    8mm

This particular power supply is (Apple p/n: 614-0326)

Note: According to Alex, capacitors would not exceed 32mm length. But also note that the cable wiring comes over the top of some of those capacitors on the right front section of the PSU. If the capacitors are too high, the wiring will not clear the PSU cover.

“Jim – do you have a pic of a 20″ iMac G5 power supply guts? Mine had the bulging/leaking capacitors. I removed them but need 2 reinstall and lost my notes as to which went where. On the top right hand side area is where they go.

I need to know where each size goes back. They are as follows: 1200mF 16V, 3300mF 10V, 2200mF 10V and 1000mF 10V any help is greatly appreciated.”

Sorry, I haven’t taken the 20 inch power supply apart, so I don’t have any pictures. I’d appreciate it if someone else can send pictures to me of the 20 inch model and I’ll post them here. Click my email address “James” on the right side to send images. Special thanks to Alex B. for his Power Supply iMac 20” picture above.

Additionally, if anyone finds a source available for engineering prints, technical drawings, or electronic schematics for Apple iMacs, please send me an email notice or send attachments to James. James is my clickable email address located on the right side of the website, just above “Chat with Jim Warholic” when I’m available online. I and others would really appreciate the circuit board schematics if you have them. Thank you, Jim Warholic

There is another option worth exploring for the Apple iMac G5 Power Supply. The option is to possibly convert a standard PC ATX power supply and use it for the Apple iMac. Wiring changes on the P1 pin-outs have to be made first. See the following note and image.

Accelerate Your Macintosh! News Page

iMac G5 Power Supply Connector Pin-Out (Voltages)
“I haven’t been able to find this anywhere using Google, so I took apart my iMac G5 (17-inch rev A) power supply and made a pin-out diagram.
-Chris N.”

Do not attempt the following if you do not know what you are doing. Severe damage could result. See note above concerning the information provided here. Compare the Apple iMac Pinouts diagram with that of the ATX Power Supply Pinouts Diagram. Pin modifications need to take place before plugging it in. Note also, there is a 24 Volts output on the Apple iMac Pinout diagram that is missing on the ATX Power Supply Pinout diagram. However, based on a thread in an online Apple Forum at InsanelyMac, titled iMac G5 Power Supply Question, a person as recently as January 2008 modified an ATX power supply and didn’t use the 24V, but I think he used an external monitor, and the iMac worked with this setup. Some folks indicate that the +24V is used for the internal backlit display. See quotes: “+24V is used to power the LCD inverter” and “24VDC line looks to be for the display (backlighting)”. Read full quotes in context at InsanelyMac Forum.

With that iMac G5 mod in mind, maybe someone can come up with an external power supply box, and just plug it in to the iMac P1 plug on the motherboard. Another person also emailed me in October of 2008 and mentioned he had this ATX power supply working for an Apple iMac g5 too.

This was recently posted as a comment by another person for the pin outs and voltage information: Note, I have confirmed this pin out information. Update: The various pinouts have been confirmed by at least one other customer also. Click the how-to link for more details about how to measure the iMac G5 power supply voltages and turn on the PSU when the PSU is removed from the iMac computer.

My 20″ iMac Power Supply connector – P-1

1. +3.3 – BlackA3B 12. +3.3 – BlackA3B
2. +3.3 – BlackA3B 13. +12v – BrownA3B
3. GND – BlackB4B 14. GND – BlackC4B
4. +5v Gray/PurpleA4B 15. On/Off – Gray
5. GND – BlackB4B 16. GND – BlackC4B
6. +5v Gray/PurpleA4B 17. GND – BlackC4B
7. GND – BlackB4B 18. GND – BlackC4B
8. PG – Blue 19. +12v – BrownA3B
9. +5.1Vsb – Purple 20. +5v Gray/PurpleA4B
10. +12v – BrownA3B 21. +5v Gray/PurpleA4B
11. GND 22. +20v – Brown

FYI: More information for measuring the voltages can be found at my how to measure iMac G5 power supplies article. Be sure to read the article comments section for additional details.

Pin 22 supplies Panel voltage. Using a modified ATX Power supply (Need 12+ on pins 12 and 18), and the good 20 volts on the dead Apple Power Supply and a ground, I was able to boot my 20″ iMac using the combination of both power supplies. Someone else posted the pin out elsewhere on the web. I replaced just the domed capacitors on my power supply and still no luck. Can some of the capacitors be bad and not be domed? Can you check capacitors on the board without removal? Some go to infinite and stay, other go to infinite and fall back to zero when using an ohm meter?

A few points to consider when checking capacitors in the circuit and on the circuit board. It doesn’t always give the correct reading with a ohm meter whether using digital or analog  meters because of other components affecting the readings of what you might be trying to check in the circuit. Yes, capacitors can be bad without physically looking bad. The electrolytic juice can dry up on the inside. And one more point that I would like to make, it sure would be nice to have a circuit board schematic for the power supplies in my hands. Feel free to send me one if you have it. Thanks.

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3/18/2009 Update: Installed new power supply in this iMac 17 inch G5 computer. Success! Installed keyboard and mouse too. Now I need new software for the white house.

A important note here is that I recommend only using “new” low ESR, long life, computer motherboard grade and switching power supply grade capacitors for all repairs. Do not use unknown surplus caps, or even new or surplus caps that have been sitting on the shelf for ages. My power supply was too far gone. It had something else blown in it.

I have the extra long life capacitors (rated at 10,000 hrs. on the large uf rated capacitors) and all are low ESR ratings for the power supplies, in stock now. Please take a look and compare these Apple iMac power supplies to your power supply before purchasing.

Click Here to Buy Capacitors, or click here to match up your iMac PSU variation to the detailed pictures. Purchase high quality, low ESR, mother board grade, long life, high temperature rated capacitors for your iMac G5 PowerPC mother boards.

If your iMac power supply doesn’t look exactly as above, or would like to have a free consultation, and provide a visual evaluation for me to take a look at please send in your Apple iMac G5 pictures, to compare.

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Apple iMac G5 Motherboards DIY Repairs How to Fix Bad Caps Guide




Purchase high quality, low ESR, motherboard grade, long life, high temperature rated capacitors for your iMac G5 motherboards and PSUs. Go To iMac G5 Take Apart Procedure Help please, my beautiful Apple iMac G5 Computer is broken. The first in a series of how to fix an iMac G5 PowerPC mother board (MOB). This procedure [...]






Click to read more about: Apple iMac G5 Motherboards DIY Repairs How to Fix Bad Caps Guide
Apple Capacitors For Sale - Click Here

Purchase high quality, low ESR, motherboard grade, long life, high temperature rated capacitors for your iMac G5 motherboards and PSUs.

G5
Go To
iMac G5 Take Apart Procedure
Help please, my beautiful Apple iMac G5 Computer is broken.

The first in a series of how to fix an iMac G5 PowerPC mother board (MOB).

This procedure is for repairing the iMac G5 MOB Logic Board and video problems. For Apple iMac G5 PSU, see how to fix an iMac G5 power supply.

Click here for Apple iSight G5 logic board model information.

The success rate for these do-it-yourself repairs are quite high, at greater than 95% when following the instructions. *** See note at the end of the article.

Hello to the French MacGeneration.
Bonjour à la France MacGeneration.

Translate this page using Google Translate Widget on the right.
Traduire cette page en utilisant Google Translate widget sur la droite.

I had to get the lead out when it comes to repairing the Apple iMac G5 PPC motherboard problems. Beware; please read these MOB iMac G5 repair instructions carefully before attempting this procedure for replacing of the capacitors on an iMac yourself. This Apple iMac G5 logic board repair is not as difficult as it sounds. If you wish to save a substantial amount of money on iMac repairs and mother board replacement, possibly have a buddy that can help, or even have some experience yourself with a few handy tools at your disposal, or have a local computer repair technician that might be willing to do the job, or willing to take on a challenge yourself and have a dead mac you wish to revive, then this is the best Apple iMac G5 repair procedure for you. Also, beware of the time commitment involved with this Apple computer repair. “Be prepared,” is the old Boy Scout motto, and that is no lie when it comes to tackling this Apple product repair yourself. iMac serial numbers are listed below to see if your Apple serial number was covered in the original problem.

Additionally you may also go to any Apple Retail Store with a Genus Bar, and have the Apple folks take a look inside the G5 and look at the caps on the iMac logic board for you. Find the nearest Apple Retail Store – Genius Bar in your area, and take your Mac and get in the queue, or better yet, make an appointment online for the Genius Bar. Apple provides technical support for Mac, iPod, Apple TV, and iPhones at the Genius Bar too.

Apple iMac G5 Hard Drive Data Recovery for those that want to recover the information from their hard drives on a dead Mac.

Apple iMac G5 PowerPC Motherboard Repairs Picture Before

Apple iMac G5 Motherboard Capacitors Problem
1st Generation Apple iMac With Bad Caps

This is a close up view of the Apple iMac G5 Motherboard (20 inch model) with the bulging, leaking, and exploding capacitors problem. Take a look at Fat Caps & Ripple Current for more info into engineering and design of electronics equipment. This is a first generation model pictured above. Go to the bottom for second generation iMac G5 comparison picture. This Apple G5 PPC motherboard is three years and two months old. The symptoms of the problem were: video shaking, video disappearing, video lockup, system lockup, intermittently could not power down, intermittently powering up problems, and strange program lockups. Here is a YouTube Video from someone else that shows a very similar Apple iMac G5 startup problem with the video display. Note the vertical lines in the video display.

After Apple iMac G5 Motherboard Repairs Picture

Apple iMac G5 Capacitors
Location of Capacitors on MOB Next to Power Supply on 1st Generation Apple iMac G5

Article updated 12/17/11: Very Important! High Quality Low ESR capacitors, computer motherboard grade, 105ºC, 10mm X 16mm, caps are available for sale in kit form.

The logic board capacitor sizes included in the kits, are the original sizes of the capacitors on the logic board; making your job much easier to replace them. Important Note: The caps are a perfect fit for both diameter and height requirements, which is very important for the caps’ clearances to the back cover and extremely close mounting requirements. Reference the article: Fat Caps & Ripple Current for more electronics engineering & design insights.

International shipping is available for most countries worldwide. If your country isn’t listed for a shipping destination, please let me know to add your country to the list. Please provide your full name (first and last name) when ordering capacitors. Please refer to the Shipping Page for ordering and shipping information.

Send me an email if you would like to purchase ten or more iMac G5 cap kits, along with a note of which of the different cap kit sets you are interested in. Note: Apple early and late model iMac G5s with the PowerPC processor have different quantities of caps required on the MOB. Capacitor information is provided at my secure eCommerce website. Visually verify what capacitors your Apple iMac requires based on the pictures, and bring your iMac G5 back to life today.

Send me an email with any questions, or other special order requests. I have the power supply cap kits available too. Compare your PSU to the pictures. Feel free to contact me any time, with any questions. Take a look at the PSU cap kits that are available for purchase.

Apple iMac G5 Motherboard PowerPC capacitors replaced. The iMac mother board pictured above shows the locations of the new capacitors installed. Note: The heights and diameters of the new capacitors are slightly bigger in this picture, than the original caps. Upgraded to 1,800 uf 10 volts from the original 1,800 uf 6.3 volts. Please note these were larger diameters and taller than the original ones. They were a very tight squeeze between each of the caps. Back cover still clears (barely clears) all components. This information is for documentation sake. I don’t really recommend going up in the heights and diameters here. That is why I am selling the proper size caps for the mother board. If higher voltage caps, with the correct capacitance, good maximum current ratings, low ESR ratings, and temperature ratings were available, in the same exact physical case sizes, it would be OK to install those. However, higher voltage caps are not available in this size packaging.

Important notes are as follows. It appears as though lead free solder was used and a polymer was coated on the assembled motherboard on the bottom. A very hot soldering iron is required. Doing it yourself is not for the faint at heart. But fear not, you can do it if you follow this procedure.

It’s pretty easy to open the iMac case (first and second generation iMac models) and visually look at the caps. Simply lay it face down on a soft cloth. Loosen completely, the three screws on the bottom edge (Note: the screws will stay in), then just lift the back cover off from the bottom up. Visually inspect the capacitors for signs of expansion or tops that are rounded even slightly are an indication of bad caps.

Once you determine the status of the caps, then everything has to be disassembled, beginning with the removal of the power supply, which also can be a victim of bad caps and/or poor engineering, (see: DIY G5 power supply repair) in order to get to the bottom of the motherboard. Refer to the various Apple iMac G5 user and do-it-yourself part replacement manuals for details and visual instructions on how to remove various items. The cover is easy to take off by simply turning the three screws completely counter clockwise on the bottom of the computer’s lower edge and then lifting up the rear cover. The power supply (see: Apple Power Supply Removal and Replacement Instructions) then can be removed by unscrewing the mounting screws and disconnecting the main plug and the ambient light sensor cable (if you have an ambient light sensor model) to the motherboard, and partially turn the middle screw (about 5 turns clockwise) on the bottom of the case, which releases the back cover clamp, and the PSU will then lift out. Be careful not to damage the automatic ambient light sensor mounted on the bottom edge of the power supply unit. See this YouTube Video for what is inside the iMac G5 Computer. However once the cover is removed, the rest of the computer disassembly is quite a delicate task for most non technical people and requires special tools. Apple never actually intended for the end user to remove everything that I removed in order to get to the root of the matter.

A Torx screwdriver is not necessarily needed, though it would be helpful to use one. Check out the very handy magic screwdriver with the telescopic shaft with various size TORX bits for the mother board and other items. I had some precision screwdrivers that fit somewhat precisely in the fasteners, but it certainly would have been easier if I had the Torx screwdriver to begin with.

Here are some additional service notes and soldering tips. In addition to requiring a super hot soldering iron, one with good heat transfer and quick heat recovery, (a 60 watt soldering iron minimum is recommended) you may also need to grind off some of the polymer resin that is on the bottom of the circuit board, covering the capacitors’ leads, in order to get access to the lead free solder in the first place. See Soldering Tips for Lead-Free Soldering for detailed soldering tips and information. A proper soldering iron will make your job much easier and be able to quickly remove the capacitors from their mounts without having to do any special resin removal. I suggest ordering wider soldering tips, for use with a good quality soldering iron for a hotter and faster concentration of heat transfer. Soldering TipsIf you don’t use a hot enough soldering iron, the solder will never melt; you will just barely heat up the circuit board, and the capacitors will not come out. Also, if you have to
o small a tip, the heat will not transfer to the mother board very well, and the tip will cool down too fast when trying to melt the lead-free solder. If anyone would like to make a suggestion for a good quality soldering iron, at a reasonable price, with quick heat recovery, that can melt the lead free solder on this Apple motherboard, let us know here.

CHIPQUIK at JWestSales.comWhile removing the 20 capacitors on the G5 logic board, I experienced broken leads from capacitors that were falling apart, and leads that pulled out of the capacitors themselves, because of the extra heat that is required to melt the lead free solder in the first place. Note the following section is included for information purposes only. Some folks have recommended I remove this reference to drilling the circuit board holes out. While this is not a recommendation of circuit board drilling, I have included it here only as to what I had to do to fix the problem. Others may have a much better “hole” cleaning solution. In fact, I highly recommend reading about the “pin point tip” desoldering trick, the new Chip Quik desoldering alloy and flux, and the importance of using a proper soldering iron first. To begin with, I had to use a Dremel power tool in various ways, though with a hotter and greater wattage soldering iron designed for lead-free soldering, which I bought for future MOB repairs, the following would have been a non issue. Prior to removal of the G5 caps, it was first necessary to grind off the polymer resin and some of the excessive lead lengths from the old capacitors with a small grinder tool attached to the Dremel, and then drilling out some circuit board holes with a number 72 (0.0250 inch) solid carbide drill was what I did when the old cap leads broke off in the holes of the printed circuit board. Beware of, drilling the holes out could damage the circuit board and break carbide bits inside the holes. That would not be good and making it most difficult to fix. Suggest using the Chip Quik desoldering product here instead of drilling out the pads on the PCB. Also note that drilling the holes can damage the through platting which is designed for connecting the top and bottom hole surfaces of the PCB, and might also be used for connecting to other traces and layers of the multilayer PC board. This would also make for a really bad through solder hole connection on the new capacitors being installed.

When replacing the capacitors it is important to note which are the positive and which are the negative leads when installing in the board. New capacitors generally have a long and short lead (short lead is usually the negative lead) along with a negative indicator written on the side of the cap itself. Warning: Do not install capacitors in backwards, or you will blow up the new caps and possibly damage the circuit board. The circuit board has the positive hole marked on the printed circuit board itself. Here is a how-to demonstration of how to replace capacitors. Also, keep in mind when soldering your new capacitors to the motherboard, if you just have a round blob of solder on the bottom of the board, without it fully flowing through the holes, you can have cold solder joints. If you place heat on the legs of the caps for too long, you can also damage the new capacitors. A very hot soldering iron with quick heat recovery, and a wide tip is the best solution. See notes above about the recommended soldering iron. More information at: Soldering Tips For Lead-Free Soldering.

Special Attention to Details Area. At this point in the iMac repair process, after the new caps are completely installed, and properly soldered in the holes on the motherboard, you must trim off the excess new caps’ lead lengths on the bottom surface of the motherboard. Take a pair of diagonal cutters, and snip the leads to the proper lengths, making sure you do not get any metal fragments lodged in the motherboard or inside the chassis area of the iMac computer. Failure to cut the leads to the proper lengths could result in short-circuits, damaged capacitors, blown electronic components, and a blown iMac motherboard or power supply unit.

iMac Logic Card Bottom Side View

Once the capacitors are replaced on top of the motherboard, then it is time to reinstall the motherboard back into the chassis. Pictured above is the bottom of the MOB logic card, with the small square just to the right of the “.com” which is the location of the main processor (CPU) that protrudes from the bottom of the logic card. Do not try to remove this processor chip. Clean this area and the metal heatsink area that matches up to the CPU with alcohol, and apply fresh heat sink compound. I suggest when ordering the capacitors that you also order the thermal paste heatsink compound at the same time. You can order the thermal compound online from my J West Sales Store.

From George T.

“First off, the cap replacement fixed all the prior problems: i) endless blue screen on normal boot but OK with safe boot; ii) video breakup and horizontal bars; and iii) excessive fan speed. Now to the issue at hand…

The first thing the CPU does, based on ROM instructions, is check the RAM. If the RAM is OK the chime sounds. Therefore, if there is no chime, either the CPU is not working properly or a RAM chip is defective. This test covers the basic hardware and comes before the hard drive boot starts. The 3rd LED comes on early in the hard drive boot, but definitely after the chime.

My problem was no chime, and the reason was that the CPU wasn’t working. The CPU wasn’t working because I slopped some thermal grease over the circuit board items above the CPU. These items are marked “RAM clock” on the board.

Internet research revealed that the thermal grease is full of metallic silver. Furthermore, although there is little or no electrical conductivity, the grease is very capacitive. If it is sitting on the components, or even above the insulating copper tracings of the circuit board, it has low impedance at the clock frequency — it is a virtual short circuit. Once I cleaned off the grease, the board worked properly.

I would suggest that you incorporate this caution in your otherwise excellent instructions.”

Jim W. “Thank you George for the great insight.”

Arctic Silver Inc. manufactures a very good quality thermally conductive grease for modern high-power CPUs for Apple, Intel, and AMD, along with other high-performance heatsinks or water-cooling applications. Arctic Silver manufactures the Arctic Silver 5 product and the Arctic Silver Ceramique thermal compounds, and are world renown as being two of the best thermal heatsink compound options available. CPU Overclockers rave over Arctic Silver products.

When applying the Arctic Silver thermal paste compound (either the Arctic Silver 5 or Céramique 2), less is better, (see the warning on the left) paper thin is best. Please review instruction sheets for applying Arctic Silver 5 and also the Arctic Silver Céramique 2 instructions of use and proper application procedures. On Motorola chips, I use the covering of the whole surface with a very thin layer method as opposed to a dot in the middle method. Just be sure that very little if any comes out of the edge of the chip when the board would make contact with the heat sink. The way the application works is, the thermal paste fills the minor imperfections in the metal surfaces and removes the air spaces between the two joining metal surfaces and helps improve the heat transfer between the CPU and the heatsink. See image above for the the small square area right location, for the thin application of the thermal grease. Check out this Thermal Paste Comparison from Techware Labs review of the pros and cons of using the most popular thermal pastes available at the time the article was written. The article, while being somewhat dated, provides good insights into the differences between Silver Grease and Silicone Paste, and which is better for a computer CPU heatsink application. I would stay away from the silicon paste compound, because quite frankly, silicon paste or silicon grease does a poor job of keeping the CPU cool under load conditions based on the test results at that time.

Believe it or not, I have to say the finished project has worked like a champ. As a matter of fact, I have used the same iMac G5 here to do the pictures with a program called Skitch, and posting this article using Firefox running on the iMac too.

At this point in time, I’m not sure I would use any of those Rubycon Caps again. As the old saying goes, “Fool me once, shame on you; fool me twice, shame on me.” Rubycon, why did you use an improper electrolytic recipe? Was it cheaper to make those caps with the cheap electrolyte with the missing ingredient?

Rubycon MCZ Capacitors Bad CapsNote: I inspected my work a couple of weeks later, and decided to replace the five other capacitors also. I found some evidence online that these other capacitors go bad too. The 20 capacitors that I first replaced all looked good. Upgraded these five additional caps from the original factory installed 1,000 ufd, 16 vdc caps, to 1,000 ufd, 25 volts DC, operating temperature range: -55º to 105ºC. I should point out here that these were a larger diameter and taller than the original ones. They were a tight squeeze. I picked up both sets of capacitors at Halted Electronics a surplus store in Santa Clara, CA. They also have some new electronic components available at the store too. Generally speaking, it is usually OK, and advisable, to increase the DC voltage rating of the capacitors while maintaining the same MFD, microfarad rating. Don’t cut corners. As a suggestion, if you see any of the capacitors that have problems, it is highly advisable to replace the entire group of caps at the same time. If one or two of the caps are in the failure mode now, they would more than likely all be destined to fail in a very short time.

As an aside note, I included the previous paragraph information in this article as a historical troubleshooting and engineering evaluation note. I would suggest not installing surplus caps as a general fix for this problem and subsequently have installed “new” caps in this iMac. The problem with “old” surplus caps, you have no idea how old and long the capacitors have been sitting on the shelf with potential “shelf life rot”. I actually witnessed this capacitor shelf life rot on some of the first capacitors I looked at in the surplus bins before they got more from the back room. Many of the surplus caps are generic brands, or do not have proper low ESR ratings, or are general purpose capacitors that should not be used in mother board applications. Note that as of 8/15/2010, as I mention above, I upgraded this originally repaired iMac G5 with the surplus “old” caps to the proper sized and proper voltage rated “new” capacitors. Don’t shortchange yourself in your repair efforts here; order proper low ESR motherboard and power supply grade capacitors.

LED Indicator Lights

iMac G5 LED Indicator Lights

The LEDs on the main logic board (motherboard or MOB) indicate the following:
* LED #1 means it is detecting trickle voltage from the power supply unit, PSU. If you don’t see this LED, with the machine off but plugged in, it is not a good candidate for PSU repairs unless fuse is blown on the PSU itself, and the PSU should be replaced in this case.
* LED #2 comes on when the MOB sees all the correct powers (proper voltages present from PSU).
* LED #3 indicates the computer and LCD are talking (communicating) OK.
* LED #4 is strictly an overheating indicator LED, and should not go on under normal circumstances.

Another interesting bit of information regarding noisy iMac G5 fans and internal temperatures that I discovered after the G5 motherboard repair, it became apparent, the computer fans were running a lot quieter. No more Hoover Vacuum cleaner sounds. Also, the overall temperature of the computer is operating at lower temperatures in my opinion. I found this free Temperature Monitor program for keeping track both instantaneously and in a graph chart form, of what the CPU, Hard Drive, and Smart Disk drive temperatures are operating at. I did not have the program installed prior to the problem, but after I repaired the printed circuit board, I installed the temperature recorder and discovered that the CPU temperature does not get much above 65 degrees C, even with a warm ambient room temperature. The average temperature of the CPU is somewhere in the 58 degree C range (136 degrees Fahrenheit). Note: I keep my computer running for days and weeks on end.

I am still a bit ticked off that I had to go and do this myself. I had the Apple extended care warranty, but I missed out on the free repair by two months. If I had the problem occur two months earlier, Apple would have covered it free of charge. Apple never sent a message concerning the problem. It took some investigative work to find out that they had issues with the capacitors leaking, but they downplayed the severity of the problem.

This should not happen with a product three years old. In Apple’s defense I can tell you that I found evidence that many other computer manufacturers also had the capacitor problems from buying low cost capacitors from a stolen electrolytic capacitor recipe from Taiwan. See this video showing computer circuit boards with bulging, leaking, and exploded capacitors on board from a variety of computer manufacturers. While I am a fan of Apple products, I just have to say this is not one of their stellar computer products moments. I’m sure it was a business decision to not have a product recall, but I think they should have had one. Of course, I guess you could say, I’m a little biased on this issue.

Yes, the Apple Store folks were nice enough to take a look inside the iMac at the local Mac Genius Bar, and give me a heads up on what the problem was, though it only took a five second look inside for the Apple guy to tell me that I need a new motherboard, and oh by the way, the total cost (approximately $750.00) was going to be two thirds the cost of a brand new computer. The Apple Store guys suggested I buy a new Apple desktop computer, one that is faster and better.

I said, “not today.”

Inside 1st Generation Apple iMac G5 20 Computer

Inside Apple iMac G5
Location of Major Components in 1st Generation Early Model Apple iMac G5 20

Here’s what you get (pictured above) inside the Apple iMac G5 Desktop computer. CD/DVD in the upper left, two fans in the top center, hard drive top right, two memory slots available for up to 2 GB of two 1 GB DDR PC 3200 memory sticks, power supply in the lower section, and the mother board in the middle. Look closely, and you can see the on board battery for the motherboard.

Apple Second Generation iMac G5 Computer

Compare your Apple iMac with the picture above. Is yours an early model first generation or late model second generation Apple iMac G5?

Printout this PDF file of the Apple iMac G5 Motherboard Repair article for reference before you take a bite of your Apple apart. Opun the back door.

iMac G5 17 & 20 Inch Models

Here is a Apple link on how to identify your iMac and how to check the EMC number on the bottom label.

Contact Me

As one last thought before the night is over, lead free solder is a pain in the rear. Repairing all types of electronics is going to become increasingly difficult with these high temperatures required to remove and install new components in their place. We are becoming more and more, a disposable society.

Also, I think it is quite comical reading the Apple repair extension program especially the section about not fixing the desktop computer yourself, now that I have fixed it myself. And, the one that says if you don’t have any of these problems there is no need to do anything, “just wait for it to break after warranty,” my two cents added.

Apple Capacitors For Sale - Click Here

Read it for yourself. I guess I am breaking all the rules here.

And for those that want to check out their iMac G5 for the extended service, here is the quoted information from Apple support.

iMac G5 Repair Extension Program for Video and Power Issues

November 2, 2006

Frequently Asked Questions

iMac G5 Repair Extension Program for Video and Power Issues
The iMac G5 Repair Extension Program for Video and Power Issues applies to first generation iMac G5 computers that have video or power-related issues as a result of a specific component failure. If your iMac G5 is exhibiting any of the symptoms listed below and your computer’s serial number is within the noted ranges, your computer may be eligible for repair, free of charge. If Apple or an Apple Authorized Service Provider (AASP) determines that your iMac G5 computer is eligible as part of the program, the repair will be covered by Apple for up to three years from the original date of purchase even if your iMac G5 is out of warranty.

This is a worldwide Apple program.
Affected systems will exhibit one of the following video- or power-related symptoms:

  • Scrambled or distorted video
  • No video
  • No power

Note: If your iMac G5 is not experiencing any of these symptoms, you do not have to contact Apple or any Apple Authorized Service Provider.

Which iMac G5 computers are affected by the iMac G5 Repair Extension Program for Video and Power Issues?

The program is available for certain first generation iMac G5 models that were sold between approximately September 2004 and June 2005 featuring 17- and 20-inch displays with 1.6GHz and 1.8GHz G5 processors.

The affected iMac G5 computers have serial numbers where the first 5 digits fall into the ranges noted below.

Serial Number ranges:

  • W8435xxxxxx – W8522xxxxxx
  • QP435xxxxxx – QP522xxxxxx
  • CK435xxxxxx – CK522xxxxxx
  • YD435xxxxxx – YD522xxxxxx

Some second generation iMac G5 computers have serial numbers that fall within the upper band of the ranges listed below. Only first generation iMac G5 computers are affected by this program.
Where do I find the serial number of my iMac G5?
The 11-digit serial number is located on a label under the foot of the iMac G5. There is a bar code underneath the serial number.
To view the label, hold the sides of the iMac and gently lay the computer face down on a soft, clean towel or cloth.


Is the iMac G5 Repair Extension program available for other Apple computers?

This program applies only to the systems noted in this FAQ. Other versions of the iMac G5 line are not part of this program. Click here for more information on how to identify iMac G5 models.

How can I tell if my computer is affected by the component failure identified for the iMac G5 Repair Extension Program?

An Apple technical support representative or an Apple Authorized Service Provider (AASP) will need to physically examine your computer to determine if the component failure identified for the iMac G5 Repair Extension Program affects your computer and, if so, arrange for the repair.

How can I participate in the iMac G5 Repair Extension Program?

To participate in the program, please bring your iMac G5 to the Mac Genius Bar at your local Apple Retail store or Apple Authorized Service Provider (AASP), or call your local Apple Contact Center.

Apple Retail Store

Apple Authorized Service Provider

Apple Support Contact information

What if my computer exhibits symptoms not caused by the component Apple has identified for the iMac G5 Repair Extension Program?

It is possible that your iMac G5 may exhibit video or power issues that are unrelated to the component failure identified by Apple as part of this program and are not covered under this program. Apple or an AASP can help you troubleshoot these issues. If your iMac G5 is not covered under warranty or an extended service agreement, such as the AppleCare Protection Plan, repairs for other issues will be made at your expense if you request that they be made.

I have a remanufactured iMac G5 that fits the description noted. How can I determine whether my iMac G5 qualifies for the program?
If your iMac G5 is one of the models listed and exhibits one or more of the symptoms above, please bring your iMac G5 to the Mac Genius Bar at your local Apple Retail store or Apple Authorized Service Provider (AASP), or call your local Apple Contact Center. An Apple technical support representative or an AASP will examine your computer to determine if the component failure identified for the iMac G5 Repair Extension Program affects your computer and, if so, arrange for the repair.

Is there a cost for participating in the iMac G5 Repair Extension Program for Video and Power Issues?

If Apple or an Apple Authorized Service Provider (AASP) determines that your iMac G5 computer is eligible as part of the program, the repair will be covered by Apple even if your iMac G5 is out of warranty. Customers are responsible for transportation costs to eligible ASPs/retail stores.

How long is the iMac G5 Repair Extension Program available?

The program covers affected iMac G5 computers for up to three years from the original date of purchase. Apple will continue to evaluate the repair data and will provide further repair extensions as needed.

Does the iMac G5 Repair Extension Program extend the warranty coverage on my iMac G5?
No. This program does not extend the standard warranty coverage.

Are there any known safety issues caused by this component failure?
No.

Can I determine if my iMac G5 has the component failure and fix it myself?
No. Apple or an Apple Authorized Service Provider (AASP) must evaluate whether your iMac G5 computer is eligible as part of the program and then conduct the repair.

If my iMac G5 is still under warranty, how does this program affect me?
If your iMac G5 is eligible for the program and within its warranty period, you will have your system repaired at no cost to you. If your iMac G5 experiences the symptoms described above and is determined to be eligible under this program by Apple or an AASP after your Standard One Year Warranty expires, the program covers affected iMac G5 computers for up to three years from the original date of purchase.

Home >Support > iMac > iMac G5 Repair Extension Program for Video and Power Issues

*** Just as a reminder, it is also a good idea to check your iMac G5 power supply. A bad power supply, will produce excessive ripple on the output voltages because of bad internal PSU capacitors, and can cause your new capacitors on the MOB to quickly fail. It is not hard to check the PSU caps. Go to the article on the Apple iMac G5 Power Supply for more detailed information and what you should be aware of. I have the complete PSU cap kits in stock. For a list of the capacitors required on the PSU, take a look at the Inside the Apple iMac information articles.

A Few Concluding Remarks

  • Do a quick visual inspection of the inside of your iMac G5 for bad caps.
  • Replace both types of caps completely even if one or two is visually bad, since it is most likely the other caps are in a failure mode too.
  • A good soldering iron or station is most desirable for this DIY project. Use good lead-free soldering techniques.
  • Inspect your iMac G5 Power Supply too. Bad caps in the PSU can directly affect the caps on the MOB.
Note: If you have any questions or comments feel free to email me. I’m always ready to answer a question for you, and very much appreciate your comments and feedback. Thank you. Best regards, Jim

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