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Apple iMac G5 Power Supply Issues and DIY Apple Repairs | According to Jim

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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.

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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  • Hilal says:

    My iMac (mid 2008) 20″ keep shutting down. Took it to Apple and and outside vendor and they say there is nothing wrong with the machine and that it could be my wall out let. They checked the power supply of the machine, but still no problem there. I have a surge protector with a modem, a printer, an Airport Expree and an alarm clock, but non goes off except the iMac. What could be the issue?

    December 9, 2010 at 3:16 PM
  • Jim Warholic says:

    I would first try plugging it in another outlet, or even plugging it in in another room, to verify that the surge protector is not overloaded. If the iMac still turns itself off, then you know that the iMac has a problem. Apple and outside service vendors don’t always get the diagnosis right. Nor, do they have the time to run extensive tests, by loading videos and other programs to verify that the temperatures don’t overheat when taxed by the intensive CPU processes running.

    Additionally, you could open the PSU (which I doubt the Apple store or the Apple authorized service rep inspected) to verify that none of the capacitors are bulging. This would be a good time to inspect the capacitors yourself on the MOB too. Any bulging at all, especially bulging tops on the caps is a sign of bad caps. Refer to my other online articles for reference information on MOB & PSU capacitor checks and PSU voltage measurements. Article links can be found at the Apple menu above, or the Apple link here.

    One other thing, I would also suggest loading the free temperature monitor and measurements program or the free iStat Pro to monitor everything that is going on with the computer, including fan speeds, temperatures, CPU and memory usage statistics, network and processes running, and other items.



    December 9, 2010 at 4:41 PM
  • Hilal says:

    Thanks Jim. Appreciate it.

    December 10, 2010 at 12:59 PM
  • Thomas says:

    Jim, thanks so much for your troubles in sharing your experiences with this issue that reflects big business callouness to their unwitting customers. If only there was a way to force them to own up to their product incompetencies and make them pay. Anyway, I just finished reading most of your site and wonder if you have ever received a schematic of the power supply. I have a 20 inch G5 bought in Feb 2005 (first generation) which had the mother board replaced under Apple care within the first year or two. It is now failed again. I am going to see the Apple ‘geniuses’ tomorrow to see what they have to say. I am not bouyed with enthusiasm. I am guessing that I will either need to buy a new power supply or do the tedious work myself to replace all the caps via your helpful offerings. If I must buy a new power supply unit, I am likely to tear the old one apart in order to create a schematic of it. If you are still interested in having this information, I would be willing to comply. Best Regards, Thomas.

    December 29, 2010 at 7:28 PM
  • Jim Warholic says:

    Hi Thomas,

    That would be great if you could take the time to reverse engineer the schematic. However, it might be a bit of a challenge, given the fact that there are surface mount components on the bottom side that are very difficult to make out exactly what the values are, and not to mention that many of the components on the top surface are not easily indicated as to exactly their part numbers.

    Feel free to email me using my email address link on the right side of the site, where it says, Email: James.



    December 29, 2010 at 8:25 PM
  • Alex B says:

    Hi Jim received your Caps the other day…5 days from USA to SPAIN…I couldn’ believe it !!!
    I,ve just had enough time to get the new Caps into my Power Supply Unit and it worked fine except for the OS being gone from the Hard Drive…as it was a second-third hand gift I didn’t get any DVD or CD and had to source myself with a new Mac OS X Tiger DVD and it now flies as if it was new…tomorrow I’ll try to source myself a new HD just in case this one dies. Anyway your site has been so helpful and I’m sure it will be in the future.

    De-Soldering the old Caps was a pain in the b**m but worth every penny spent.

    Thanks once again for your help and keep us up-to-date.


    April 8, 2011 at 6:04 PM
  • Joe says:

    Hi Jim,
    I was wondering if you might be able to help me with an issue i’m having. I have the Imac 24” G5. When i push the power button the light comes and and so does the fan – there is no audible start up sound (the wind up of the fans or anything of the sort) and the screen won’t even come on. At first I thought it could be a power supply issue but the light does come one so now I’m thinking it’s the motherboard.
    What do you think?


    April 21, 2011 at 4:04 AM
  • Jim Warholic says:

    I would try to see if it boots with the software CD/DVD. If at that point, it still does not work, then I would inspect the PSU capacitors. It is a bit difficult to verify on the 24 inch iMacs if the MOB or the PSU is the problem. You might try posting the question on the Apple forum too.

    April 21, 2011 at 8:40 AM
  • Mark says:


    More praise for your website which I have been reading cover to cover since my 20″ imac G5 stopped working about 2 weeks ago. Troubleshoot (1st led only on) pointed to logic board. Apple store genius tried to sell us a new unit, saying they no longer support our model (Gen 2, 20″ imac ALS, 2.0 processor). Inspected the logic board VERY closely and could find no caps with any hint of being bad. Took apart the power supply (version A) and immediately smelled the electric burn smell. Visual test found one 10v 2200uf cap popped and leaking. Ordered replacement cap and when it arrived, replaced the old one. Put everything back together but still no power on or any sign of life. Next plan was to do the ATX psu mod. While investigating, decided to retest the psu pinout for proper voltage, especially the 20v needed to power the display. Upon retesting, all voltages were correct. So, I thought, why not plug it in and see if it will work. Slapped the back of the machine on, and holding it together with one hand, plugged it in and turned it on with the other and got the chime and display came up. I had already taken the hard drive out to transfer photos and music to another computer, so I put it back in, screwed everything back together, PLUGGED IN THE AMBIENT LIGHT SENSOR CABLE, put the back on and pushed the power button…. NOTHING. On a hunch, took the back off, unplugged the ambient light sensor cable, put the back back on and tada: everything works perfectly. I am writing this epistle on the mac now.

    Apparently, there is some kind of short in the ALS keeping the computer from working. Since I don’t even know what it does and there are two others, I am planning on just keeping it unplugged.

    Fingers crossed and thanks for all the information,


    April 23, 2011 at 9:13 PM
  • Dennis says:


    I own a G5 1.8 ghz ppc 20″ early iMac (no sensor). I’ve already had both the mob and psu replaced under the Apple extended warranty programs. A couple of years back I lost the use of the ethernet port on it but still use it for work as a graphic artist. A couple weeks back the iMac began to consistently shutdown after I put it to sleep. I’ve replaced the pram battery, zapped the pram and reset the smu to no avail. The last option is the psu. I’ve opened the back of the mac and visually examined the caps. No bulging nor leaking. I just pulled the psu and there is no smell of burnt anything. I’ll need to buy a torx screwdriver to remove the cover of the psu.
    Do you think that if I replace the caps on the psu my problem with the unwanted shutdown during sleep will be resolved? The iMac still boots up and does everything I need it to do otherwise except for the sleep shutdown. Any help would be greatly appreciated.


    June 17, 2011 at 3:15 PM
  • Jim Warholic says:

    It sounds like the PSU, especially if there are any bulging caps inside the PSU itself. The symptoms are indicative of a power supply problem.

    June 17, 2011 at 4:07 PM
  • Dennis Fujitake says:


    You were on the money. When I opened up my PSU I found a bulging cap that was leaking. Got the caps I ordered from you and finally finished replacing them today. Tested my iMac out and the sleep problem is gone. Thanks for all the clear instructions, warnings and tips as I was a neophyte at this sort of thing.
    As soon as I get more free time I’ll tackle replacing the caps on the MOB.
    Thanks again for your great website…


    July 11, 2011 at 7:15 PM
  • DOUGLAS says:

    Hey Jim,

    I changed the caps but still no luck when I press the power button I hear a short squeak could it be the two large capacitors, or a regulator, or a transformer.



    July 18, 2011 at 12:52 PM
  • Jim Warholic says:

    Hi Douglas,

    It’s not likely the large capacitors. I suspect one of the other components has gone out. I would double check your voltages. Reference the PSU voltage posting for pinout information.


    July 18, 2011 at 4:40 PM
  • Douglas says:

    Hey jim thanks for the reply. I changed the large capacitors (couldn’t hurt) then plugged into my computer and no luck. I then changed 4 SMD voltage regulators (not easy) and I plugged it in and still no luck. But when I measure the voltages I do believe I am getting more than the last time I checked with a multimeter. Most of the voltages are about half of what they need to be though. Any ideas?



    July 22, 2011 at 1:47 PM
  • Jim Warholic says:

    At this point, it is probably best to get a new PSU.

    July 22, 2011 at 11:12 PM
  • Steve says:

    Hi Jim

    I have a 20″ ALS with graphic issues (blocks all over the screen internal and external) so fairly certain it’s the graphics chip as had done the caps. So I just purchased another that had PSU issues.

    When I powered the new unit on – LED1 is on, when you power up nothing happens – so assume needs some new capacitors?

    I took the PSU from my old unit (I had previously replaced all caps) and plugged this in it booted fine. Did a few software updates left it over night and it woke from sleep etc fine. So upgraded the ram etc. went out and left it on doing an more updates. Came back and updates requested a reboot – let it do this and when I came back the unit was off? I could not remember shutting it down. So powered to find out but came back 1hr later and it was shutdown. Now concerned.

    Long story short does not power up now – LED1 is on, LED 2 flashes quickly and then nothing ?
    Again would a new cap set sort this – I am asking as I did these 4 months back and where previously fine so puzzled.

    I have looked over the MB and cannot see any bulging caps at all. Is it possible that something on the MB or unit blew my good PSU?

    I have also plugged in a 17″ ALS PSU (does not fit inside case but for test) and the unit powered up to the login prompt fine. Have not left it attached for fear of blowing this as well.

    Thanks Steve

    August 4, 2011 at 2:55 PM
  • Jim Warholic says:

    @ Steve

    I suspect the PSU now has a problem.

    It is possible that some of the caps on the MOB, even though you do not see any signs of bulging, are bad. I have seen MOB caps that do not show any signs of problems, yet after replacing the caps, then everything worked fine. What typically happens with these older MOB caps, is the electrolytic juice drys out, and simply does not allow the capacitor to function, to properly filter out the AC ripple. Then, when a new or rebuilt PSU is plugged into the computer, the PSU has to work harder in order to produce the same DC voltages. This is when the cascading failure begins to happen.

    August 6, 2011 at 9:59 AM
  • Steve says:


    Thanks – sounds highly possible. I have the caps to do the logic board – just need to repair the PSU’s – not sure which I prefer but both need to be done now.

    On a side note

    I replaced the caps on my original logic board & the PSU mentioned above but then got square blocks on the screen that went away with the mouse being move over them – any ideas? Cooked graphics?

    I also have a 17″ ALS that did not display internally I replaced the caps next to the CPU heatsink and it worked. I then decided to replace the others near the graphics connect and the back to the left and it stopped working internally but works fine on an external connection. I have been over every cap and even have another board that does the same. Any ideas?

    Cheers Steve

    August 7, 2011 at 5:49 AM
  • Jim Warholic says:

    @ Steve

    Not sure on the graphics one.

    On the 17 inch ALS one, I suspect there might have been a cascading failure affect. Sometimes when you pick and choose only certain caps to replace, the other ones that have not been replaced are next to go. It is kind of like the weakest link. This holds true from the MOB to the PSU and from the PSU to the MOB. By only replacing a few caps at a time, the others either in the PSU or in the MOB, end up in failure mode. Then, you end up wondering whether the few caps you installed are good anymore.

    I would also double check the PSU voltages (refer to my article on how to measure the voltages on the Apple PSUs).

    I would also check all the connectors. Try reseating all of them to make sure all the pins are making contact on the board.

    One other thought comes to mind; are you sure you have good solder joints? Refer to my article on how to do lead free soldering on these thick Apple logic cards. If the capacitors are only tacked in place, sometimes they are not making a solid connection through the circuit board hole wall, and thus not getting a good connection to the top surface of the circuit board.

    August 7, 2011 at 11:02 AM
  • Alex Steines says:

    I just got done replacing the capacitors on my iSight G5 that will not start up (no fans or display). It had a couple swelled capacitors and one that was leaking. I ordered the capacitors from the link on this site and it was a breeze to install.

    Before the repair I noticed that when plugged in the power supply “ticked”, and made a very rapid and quiet clicking noise… What could this be? It remains even after all the capacitors were replaced. When plugged in diagnostic led #1 is on, but that’s it; when you hit the power button there is no change. Any suggestions? Power supply bad? Is there anything I can fix on it besides the capacitors?

    Thanks Steve, what a fantastic site with so much info!

    August 15, 2011 at 10:13 PM
  • Jim Warholic says:

    @ Alex

    Are you sure it is coming from the PSU? I have actually heard a hard drive ticking when it was moving the read heads searching the disk, but could not read it (in this case, the disk had crashed). Did you try plugging in the PSU, just by itself, and measure the voltages from the pin connector? Refer to the article link in my Apple information page for measuring the PSU voltages.

    If it is the PSU ticking, I suspect that either the small transformer is shorted internally or one of the other components is charging and discharging with an internal short. At this point in time, after double checking to make sure all the solder joints are good, it sounds like you might need a new PSU.

    August 15, 2011 at 11:49 PM
  • Kevin says:

    Jim, the symptoms Alex in comment 149 has are exactly the same as mine. I’ve heard the HD failure click many times and this is not the same. It is a ticking sound just like he describes and as SOON as you plug the power in, without try to start the computer. The LED 1 almost flickers to the same beat. Alex, if you are reading this, what was your solution?

    August 16, 2011 at 6:57 AM
  • Steve says:

    Hi again Jim

    I replaced both PSU caps and tested them in a known good MOB and the status was the same

    PSU 1 – shows trickle voltage LED1 and nothing else.
    PSU 2 – shows trickle voltage LED2 and then LED2 comes on but goes out and I hear a squeak from the PSU case.

    Any ideas?

    Something in my heads says PSU2 has another bad cap (squeaking), this leaves the 2 x large caps and the other small ones – Alex B’s pic shows one of the PSU’s Apple p/n: 614-0326 the other os 614-0366

    I should add, that I have tested both PSU voltages and I only get voltages on pins 22 & 9
    Although pin 22 is quite low 20.53 compared with the 17? ALS PSU I have which is 23.3

    Also PSU no longer does the flicker on LED 2

    September 6, 2011 at 3:11 PM
  • Paul says:

    Hi Jim,

    Do you know where I can buy those WT7515 IC chips?

    Hope you are well.


    October 7, 2011 at 12:39 PM
  • Jim Warholic says:

    That’s a tough one. I suspect try doing a Google Search for the p/n.

    October 7, 2011 at 2:28 PM
  • Simon Hewitt says:

    Notes on Electrolytic Capacitors

    All electrolytic capacitors have a finite life:

    The voltage across the plates of the capacitor, in normal use, causes electrolysis in the electrolyte solution. i.e. breaking down the solution into its constituent atoms/molecules. This process ‘consumes’ the solution because the solution is converted into various gases. The rate of consumption is highly dependent on the voltage applied (higher voltage=more electrolysis!).

    As the capacitor ages, this process begins to accelerate and eventually sufficient gas is produced to cause a pressure build-up within the capacitor, eventually causing the capacitor to ‘vent’ (pop or explode!). The score-markings on the top of the capacitor are there to ensure the capacitor ‘vents’ in a controlled manner.

    A partial venting will also cause electrolyte solution to leak out, which further accelerates the capacitor’s demise.

    Testing capacitors:

    While measuring the capacitance of a capacitor seems like the right thing to measure, actual measurements on bad capacitors will either show a good reading, matching the value stated on the side, or, most likely a higher reading. Strangely the capacitance actually INCREASES as the capacitor is dying!

    In DC filter applications higher capacitance is normally a good thing because it provides more filtering of the high-frequency ripple from the SMPSU. However in the case of comparing an electrolytic capacitor’s stated value to the measured value, this indicates a dying capacitor – This provides a poor-man’s capacitor test: Look for higher than normal readings (in addition to basic visual tests)!

    The real parameter to check is the Equivalent Series Resistance (ESR). This resistance is in series with the capacitor and so cannot be measured with an ohm-meter – A special ESR meter is required (I use a Peak ESR60 £90).

    The ESR of a capacitor is important because it IS the parameter that increases as the electrolyte is consumed. The ESR is also represents the power loss in the capacitor (Ploss = Resr x I^2), this power loss causes heating of the capacitor, which further accelerates the electrolyte consumption.

    It is very normal to see capacitors in a SMPSU that look normal (no signs of bulging, etc) but actually have a high ESR reading and are in fact faulty – Always test the ESR of all capacitors (individually out-of-circuit).

    Again a poor-man’s test for ESR is to simply feel the temperature of the capacitor. If it is hot, then there are significant losses caused by the ESR.

    Finally, increasing the capacitance values of replacement parts may seem like a like a good idea to reduce ripple currents, but be warned that going too high may mess-up the dynamics of the SMPSU causing it to become unstable!

    Hope that helps, sorry if it’s already been said (haven’t waded through the comments!!!)


    October 19, 2011 at 11:01 AM
  • Fred Penner says:

    Great site! I replaced the caps in my PSU. Now the computer works fine for about 15 minutes when the PSU starts smelling and the computer shuts down. The copper heat sink is super hot. Any idea why?

    October 20, 2011 at 8:14 PM
  • Jim Warholic says:

    I suspect one of the surface mount transistors on the bottom of the circuit board is damaged besides your blown capacitors that you had.

    October 20, 2011 at 10:32 PM
  • Joe Z says:

    Great instructions! I was able to successfully replace all the caps on the motherboard, which resolved the issue somewhat, however, I’ve still been having some issues with spontaneous shutdowns and failures to start, so I decided to have a look at the power supply. It also has some bulging caps, but while I was tearing away at the glue that holds everything steady, I accidentally ripped a tiny variable resistor in half! It was obviously some kind of preset. I still want to fix it, but the potentiometer isn’t well labeled, VR1 is al that’s printed on the circuit board. If anyone knows the value of that potentiometer or where I could find any equivalent one for a reasonable price, I’d really appreciate it.

    (Unfortunately, I think the ripple current may have burned out my graphics card permanently, but it only presents itself as periodic graphical disruption at high temperatures, so the computer is still usable.)

    October 26, 2011 at 10:24 AM
  • kenneth mitchell says:

    I have an Imac g5 that I replaced the psu and it lasted a short while before it shut down again. This year’s model I have found, is famous for over heating and shutting down. I am about to throw it in the trash, so I thought I would get your opinion as to what I might do to fix the problem. I have checked for bad capacitors and found none. The fans will come on and sound like a helicopter and run that way for a while and then the unit shuts down. Thanks for your help Mitch

    November 7, 2011 at 4:14 PM
  • Jim Warholic says:


    Here are a couple of things to consider. One, if this is the second power supply to go out in a short time, then I suspect the capacitors on the MOB are stressing out the capacitors inside the PSU. And, the other thing to consider is the capacitors don’t always look bad. In fact, the capacitors actually can dry out in the electrolytic juice, and no longer filter the voltages properly.

    It would be nice if all the capacitors that went bad would show bulging signs, but this simply is not the case. I have experienced many of the MOB capacitors that when heating up of the legs to melt the solder, the legs tend to come out of the capacitors because the internals of the capacitors are so bad, that the legs (anode and cathode plates) no longer are making a solid connection internally to the guts of the cap. Refer to how electrolytic capacitors are constructed. Additionally, the caps can actually leak out from the leg area. This is why many times the caps will not bulge on the top surface, but will blow out the electrolyte at the bottom and will not be readily apparent.

    Refer to Apple iMac G5 Logic Board repairs for more information on this area.

    November 7, 2011 at 7:08 PM

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