If upon inspection, there are absolutely no physical signs of bad capacitors, then the only way to absolutely verify is to try replacing them and see what happens. Yes, there are low ESR meters that will sometimes work to establish a good or bad capacitor, however they do not always indicate properly due to other components in the circuits.

First off, you should always replace all the caps of both groups on the MOB. Even though, you only replaced the ones that were physically bad, I suspect you have others that are also bad.

I would also check the PSU capacitors too. Refer to my other articles at my Apple menu link for more information links.

Additionally, only the first three LEDs should come on. The fourth LED is over temperature. This can be caused by bad caps, fans that are not working, or a PSU that has too much ripple due to bad caps or other components.

Regards,

Jim

Any ideas what is the problem now?
thanks!
Steve

I would be very leery of thinking the capacitors that you removed from another iMac are good. In fact, the process of removing the older capacitors, and the heat that is required to remove them from the board, could have damaged them. Not to mention that these are old capacitors, which would be highly suspect in having bad ones onboard both the 17 and 20 inch MOBs, even if the other caps are not bulging.

I would also verify your PSU voltages, regardless of if you think the PSUs are good or not.

Jim

Thanks for all instructions given on your site…

I am struggling with a small problem where maybe you know how to fix it!

I got this dead 17 inch iMac G5 (late model) and some caps where highly pregnant… yet it did start up with the fans spinning but no chime and no screen lighting up…

So I replaced them with some identical ones who where still looking OK from a different 20 inch iMac g5 (1st gen.) with a defective video card…

Anyways…

After putting it all back together but without putting most screws back in place, (just the mobo and frame connector ones) it does not startup anymore.

I tried both power supply units but the only LED lighting up is the first one… after the power cord is plugged in.

Both the internal and outer power button don’t seem to respond…

:s

Do you have any suggestions about what possible went wrong?

Thanks,

Peter

Thanks for the comment.

As far as any of the Apple products, I don’t believe Apple has ever released any schematics into the marketplace. As far as the PowerMac G5s, I have heard of many issues with the breakdown of the BGA (Ball Grid Array). In fact, some have written about the PowerMac having intermittent issues related to heat. For example, some will work only when it is cold, and others will work only when they are warm. In my estimation, there has to be some sort of connection type problem when this occurs.

A few things to consider.

The Apple Hardware Test will not always tell you what is wrong. For example, it will not tell you if you have bulging capacitors in the PSU or on the main logic “motherboard.” The only way to tell this is to open it up and visually inspect those items. Refer to the Apple manuals for dis-assembly. Keep in mind, that capacitors can also go bad without showing signs of bulging. However, bulging is definitely a sign of bad caps. Additionally, if you have a meter, I suggest measuring the voltages of the PSU. This will tell you if any of the voltages are low, missing, or have excessive AC ripple riding on the DC voltages. Refer to my other articles that can be found on my Apple Information link.

Another area that is helpful, and can give good feedback as to what may be happening, is to install one of the free temperature monitoring programs. This can tell you if the iMac is overheating. Many times this can occur because the vents get clogged up with dirt, or one or more of the fans stops working, or even the capacitors themselves are failing and causing the board to heat up at these component areas or the PSU to have to work much harder.

Here are a couple of free programs that work well for monitoring the temperature and other key system items:

Temperature Monitor by Marcel Bresink
And
iStat Pro

Hope that helps you out.

Regards,

Jim

Thanks and Best Regards
Ilija Minovski

nVidia had to pay huge amounts of money to most of the main manufacturers for this problem (Apple included), but it can take a long time for the GPU bumps to crack and cause issues. If I had an iSight G5 and got a graphics issue, its mostly likely boat anchor time.

BTW, thanks for this page, I have my dad’s Gen 1 iMac G5 20′, the only issue is an audible tick (every 15 seconds to a minute apart) that happens when the machine has booted on a startup (volume and disabling the internal speaker in the OS has no effect) and when it comes back from low screen intensity (prior to screen off) to full intensity, very annoying (was thinking I’d just pull it open and unplug the speaker) but I noticed a bunch of distended capacitors (no blown yucky ones) and saw this page. Funny thing the tick seems to happen alot more in Leopard than Tiger.

Anyways, looks like I have a nice project waiting for me…and your pages are saving alot of computers from the heap.

Tom

Yes, there are significant issues with the iSight G5s. Many schools had purchased the first and second generation of iSight models, and are starting to have issues with lines through the screens and weird artifacts show up also.

I think a lot of these problems has to do with the design. Apple seems to have squeezed the thickness of the computer down to the point that heat is trapped in internal areas, which over time, breaks down connections between the main chips and the board. I have heard of folks trying the cooking of the board to see if they can re-establish a solid connection on the BGA.

I just did a Google search and found that the iSight iMac logic boards are very different than the previous generation G5 iMacs. In addition to the possibility of capacitor problems, graphics failures are attributed to failure of the 512 MB onboard RAM (only the iSIght iMacs have onboard RAM) or to deteriorating solder joints on the GPU. There is apparently no way to fix the RAM, but the GPU can be “re-balled.” However, I’ve put enough money into this project so I’m going to pull the drives and trash the rest or perhaps sell some of the parts on eBay. Or maybe I should put the logic board in the oven at 385 degrees and see if the graphics chip reattaches! I wonder what that temperature would do the the plastic sockets on the board? Or maybe try a heat gun on the GPU?

Anyway, as I implied above, I put a lot of money and time into this repair. Jim’s instructions were great as was ordering the caps, solder, etc from JWest sales. No complaints there. And he wasn’t kidding about the challenges of dealing with lead-free solder on that super heavy iMac circuit board. It was absolutely amazing how that board would sink the heat away from the connection.

I’d always wanted a decent soldering station so I bit the bullet and bought an Aoyue 2900 unit. It included a pointed tip that I knew was worthless for the iMac board so, on the vendor’s recommendation, I also ordered a 1.2 mm bevel tip. It was also inadequate so I had to order another tip, this time a 5.2 mm bevel tip (for another $14) and it worked well to unsolder and solder the caps.

The needle (held in small “vise-grip” pliers) combined with heating from the pad side worked well to open the holes. If I had it to do over again, I would have spent less time trying to get every bit of old solder off the pads. I think that as long as you have most of it gone, you’re probably OK.

Regarding getting the iSight logic board out: On page 69 the Apple service guide says to disconnect seven connectors from the board. However, just do the first six. There just isn’t room to pull the camera board connector loose (the big circle at the extreme right on on p. 69). Instead, wait until you’ve removed the logic board screws so that you can move the logic board sideways and get enough clearance to grab those tiny wires. And when you’re reconnecting the logic board, make sure you pull the IR cable up so that it’s sitting on top of the board. For reference, it’s the black cable that you can see passing under the fan and across the rectangular heat sink on p. 68. It’s very inconspicuous and likes to hide in the depths of the iMac case after the board is removed. The IR cable is also connected to the camera board connector so it’s easy to find its source.

This iMac belongs to my 91 year old dad and right now he’s using an old G3 12″ iBook running on an external drive that has a backup of the the iMac drive. Fortunately, the Apple Store just listed some refurbed 2010 Minis yesterday for $469 and I bought one for him. It should arrive in a few days.

By the way, I should add that for over a year this iMac had been showing a small rectangular box that followed the mouse pointer around (only with some applications and not others) and also had pixelated icons in the dock and on the desktop. At that time, I found one reference on Google reporting that Apple said this was due to bad onboard RAM and that the logic board must be replaced. Since it was only one reference, I blew it off, but now I believe them.

So the bottom line is that, in my opinion, if you have an iSight iMac that starts showing graphic problems or kernel panics (fans running full blast) and you’ve ruled out hard drive, system and added RAM problems, don’t assume that it’s necessarily due to bad capacitors. Take the iMac apart, remove the logic board, and examine all the capacitors. If you find no evidence of bulging or leaking capacitors, my advice to you is to save your money and put it towards another Mac.

A couple of things that I would check right off the bat, are the capacitors on the logic board and inside the power supply unit. If any of those capacitors are bulging, then that is a possibility of the cause of your problem.

If the capacitors do not have bulging tops, that does not guarantee that they are good, but at least, if the caps are bulging, it is a visual indication that they are bad.

Another thing that you could try is plugging in an external monitor with an Apple mini VGA to VGA adapter. Refer to the link for hooking up an external monitor on an iMac G5, which by-the-way, is pretty cool to do if you have an extra external monitor around. This can actually extend your desktop.

If doing all of those things above, and the problem does not show up on the external monitor, then it is possible that the LCD screen is bad in the iMac, but by no means is that a 100% guarantee.

As far as how difficult it is to replace the LCD screen itself; I would refer to these Apple service manuals for more details on how to work on, disassemble, and replace various sub-assemblies for just about any Apple product.

One more thing, is many of these iSight models have had problems with the BGA – Ball Grid Array, that is used on the main graphics chip to attach it to the board. Due to excessive heat buildup inside the G5 iSight model, which sometimes results in cold solder joints occurring between the main chip and the BGA. In this case, some folks have tried repairing those type of issues with a process called reballing BGA with varying degrees of success.

Hope that helps you,

Jim

I have an imac G5 17 inch isight version (Nov 2005) and have the notorious vertical lines (over 30 of them) and also the white strip left of centre of the screen. Apple say that my machine is classed as ‘vintage’ so unable to help. Is there anything I can do to rid of this problem? Will a replacement LCD screen do the trick if I can get hold of one? Is it easy to replace myself? Everything else about the mac is absolutely fine.

Thanks very much

Tony

I can assure you that no, it does not “always work.”

First off, some of the capacitors are so bad (bulging and heat damage) that the legs actually pull out of the capacitors very easily to begin with when heating up the legs. Additionally, if there is any leg sticking out of the hole, when you go and grab it with pliers, the pliers themselves act as a good heatsink for cooling off the entire leg lead when trying to heat it up with a soldering iron. Then, the lead will actually break off at the top of the hole, instead of the leg coming out of the hole.

Anyway, cutting away the cap was final comment I added as a ‘last resort’ method…

The ‘wiggling method’ will remove the capacitor intact, and then the pads just need a quick clean-up with solder wick – This method always works.