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New update! Apparently blue screen causes no artifacts?! :):apple:
 

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Mine (Rev.A) had same issues, even on screenshot and vnc. Replaced the caps (with low ESR), works again.

no guarantee :)
 
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Mine (Rev.A) had same issues, even on screenshot and vnc. Replaced the caps (with low ESR), works again.

no guarantee :)

Of course not mate. But you had exactly the same issues as mine? All the same things as in the pictures and you changed the capacitors and that was it? Were yours bulging as mine?
 
Of course not mate. But you had exactly the same issues as mine? All the same things as in the pictures and you changed the capacitors and that was it? Were yours bulging as mine?

Yes, but remember rev.a and rev.b have different components so It may or may not fix the issue at yours. As others mentioned maybe you still have a dead gpu beside capacitor plague. All you can do now, replace them and try it :)

Mine didn't had a bulging, just dried out thus broken, too.
 
Yes, but remember rev.a and rev.b have different components so It may or may not fix the issue at yours. As others mentioned maybe you still have a dead gpu beside capacitor plague. All you can do now, replace them and try it :)

Mine didn't had a bulging, just dried out thus broken, too.

I understand but if I GPU was dead then there would not be any display I guess?
 
I just did a ASD test on the machine and the one test that failed (from what I could see) was the PCI ATI VIDEO CONTROLLER test which said "Data Mismatch Error" error testing failed. I was able to see a little which said in the system info that the CPU was a W8 CPU ID. Does this help?
[doublepost=1548797841][/doublepost]
Yes, but remember rev.a and rev.b have different components so It may or may not fix the issue at yours. As others mentioned maybe you still have a dead gpu beside capacitor plague. All you can do now, replace them and try it :)

Mine didn't had a bulging, just dried out thus broken, too.

I just did a ASD test on the machine and the one test that failed (from what I could see) was the PCI ATI VIDEO CONTROLLER test which said "Data Mismatch Error" error testing failed. I was able to see a little which said in the system info that the CPU was a W8 CPU ID. Does this help?
 
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G5 iMacs fail due to a number of possible reasons, the most common of which being PSU issues as well as motherboard capacitor problems.
There are two types of caps on the logic board, bulging and electrolyte leaks are evidence of failure.
I couldn't say with certainty what your problem is, but as a starter it would appear reasonable to change all 25 logic board caps on a 1st gen G5 model, or 29 caps on a 2nd gen model. NOTE: Don't make the mistake that many do in just changing out the ones that are bulging or leaking.
If you are just 'ok' at soldering I'd say don't attempt this. Even if you are very good, the difficulty is not so much re-soldering new caps onto the board, but removing the old ones.
These boards were assembled using lead-free solder, and to add insult to injury it's a multi-layer board which acts like a heatsink. You may get by with a 40 watt iron, but many claim a 60watt is required.
After having ordered a kit of caps I attempted to change them out, but failed miserably at the removal process, trying 3 different irons in the process. I then found a little Asian guy downtown with all the necessary equipment - including pro desoldering tool - who agreed to perform the task. I handed him the motherboard and kit of caps. He performed a great job for the equivalent of $30.
THIS is where I sourced the kit from - who provided first class service. He also sells a set of caps for the PSU, so that may be a follow-up requirement if the mBoard caps don't solve the problem.
I have another G5 for repair and another kit of caps, but unfortunately the little guy I used first time is no longer present. I'm reluctant to try again myself, but may do now that I have a soldering workstation. Just need extra time, as this is not one of my priority Mac refurbishment tasks.
ALSO worth a read.......
 
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G5 iMacs fail due to a number of possible reasons, the most common of which being PSU issues as well as motherboard capacitor problems.
There are two types of caps on the logic board, bulging and electrolyte leaks are evidence of failure.
I couldn't say with certainty what your problem is, but as a starter it would appear reasonable to change all 25 logic board caps on a 1st gen G5 model, or 29 caps on a 2nd gen model. NOTE: Don't make the mistake that many do in just changing out the ones that are bulging or leaking.
If you are just 'ok' at soldering I'd say don't attempt this. Even if you are very good, the difficulty is not so much re-soldering new caps onto the board, but removing the old ones.
These boards were assembled using lead-free solder, and to add insult to injury it's a multi-layer board which acts like a heatsink. You may get by with a 40 watt iron, but many claim a 60watt is required.
After having ordered a kit of caps I attempted to change them out, but failed miserably at the removal process, trying 3 different irons in the process. I then found a little Asian guy downtown with all the necessary equipment - including pro desoldering tool - who agreed to perform the task. I handed him the motherboard and kit of caps. He performed a great job for the equivalent of $30.
THIS is where I sourced the kit from - who provided first class service. He also sells a set of caps for the PSU, so that may be a follow-up requirement if the mBoard caps don't solve the problem.
I have another G5 for repair and another kit of caps, but unfortunately the little guy I used first time is no longer present. I'm reluctant to try again myself, but may do now that I have a soldering workstation. Just need extra time, as this is not one of my priority Mac refurbishment tasks.
ALSO worth a read.......

Thank you for your valuable and constructive post. I visited a shop here where I live and asked about buying a Hot Air Station for the repair job. I currently own a Hot Iron Station with a digital heat controllable system. After speaking to the guys at the shop (it is a hardware component specialist shop) they advised me to buy a Hot Air Station as I myself thought to do so. I have not bought it yet, but I intend to buy one. Did changing the capacitors help your problem? What were the symptoms before the operation and afterwards if I may ask?
 
I have a small update:

Now I have two iMac G5 20" machines! Second one seems in better form. I was thinking about reflowing the GPU with a gas burner lighter as suggested by someone. I've also seen it on YouTube. I guess using flux would be a good idea apart from changing the capacitors. What are your thoughts on this? :)
 
Symptoms on the G5 iMac were distorted lines and pixels on screen.
After change of all 25 caps, image was perfect and remains so.
I'm not a betting man, but if I was I'd wager the mother-in-laws false teeth that reflowing your GPU will change nothing.

Fwiw, I've only ever done one GPU reflow, and that was on a 27" iMac (known for Radeon HD4850 and similar) failures. I performed that reflow in a domestic oven, and was highly successful in re-establishing a perfect image from the previous violet vertical stripes. I know that normally a gpu reflow should be only considered as a very temporary fix, and I performed this as a f.o.c. favour to someone who had relegated his iMac to the closet as virtually 'dead'. That was just over a year ago, and I believe it's still running correctly - I plan to contact the owner next week to confirm (and update THIS post#7).
 
Symptoms on the G5 iMac were distorted lines and pixels on screen.
After change of all 25 caps, image was perfect and remains so.
I'm not a betting man, but if I was I'd wager the mother-in-laws false teeth that reflowing your GPU will change nothing.

Fwiw, I've only ever done one GPU reflow, and that was on a 27" iMac (known for Radeon HD4850 and similar) failures. I performed that reflow in a domestic oven, and was highly successful in re-establishing a perfect image from the previous violet vertical stripes. I know that normally a gpu reflow should be only considered as a very temporary fix, and I performed this as a f.o.c. favour to someone who had relegated his iMac to the closet as virtually 'dead'. That was just over a year ago, and I believe it's still running correctly - I plan to contact the owner next week to confirm (and update THIS post#7).

The problem with baking it in my oven is that it can be dangerous to use it for preparing food afterwards due to contamination. If I had kept my old oven, which I don't use any-more then I could have used it for baking logicboards, motherboards, GPUs and such. Baking it is most likely the easiest thing to do as lead-free solder usually melts at ~235 degrees. I just don't want to risk damaging other parts, but that is how it is done at the factory. I'm not entirely a rookie, but I'm no pro either. But, I do know how to solder and such. I have a professional soldering station, but I'm missing the hot air station. It is quite expensive in my country, but maybe I should make the investment. I will probably use it again on other projects. I emailed to a specialist shop earlier today in regards to proper tools and such. They will probably reply tomorrow (Monday). You guys are right I need to do it right instead of cutting corners.
 
Major UPDATE!

I have some new information in regards to the iMacs that I bought at the flea market. The second one, which I wanted to buy in the first place is an older model than the one I bought first. The model number for both of them are iMac G5/2.0 98845LL-A (ALS) PowerMac 8.2 and iMac G5/1.8 M9259LL-A PowerMac 8.1. They are both A1076 models. Older one (PowerMac 8.1) seems in better shape, but the previous owner was a hard smoker or so. The entire unit was covered in some yellowy smock. I had to clean it with different items to clean it properly. The problem was the same inside of the iMac. After cleaning it and inspecting it I could see that it was in a “better” form as it had fewer damaged capacitors. As you can see in the pictures most of them are in good shape. The mac does have some artifacts, but it is much better than the newer iMac. I am inclined to think that the problem is not the GPU as such, but mainly a capacitor problem for them both. I think they both have the same problems and both needs to have their damaged capacitors exchanged. Would it make things worse if a reflowed a non-problematic GPU? Or would it just make it “better”? Does anyone know what that black cable is for? I think it is for the harddrive sensor, but there is no plug for it? Maybe the previous owner changed the HDD?

Thank you for listening
 

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You're posting my words from the VPN thread here in an iMac thread. You okay?

I think someone has been sucking on the pipe for too long :D:D:D:D
[doublepost=1549325024][/doublepost]UPDATE

I haven been able to remove the artifacts and errors :D:p The Cleaning did the job, but I will still replace the damaged capacitors! And also upgrade the RAM to max and perhaps install a SSD in them both (if possible).
 

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I think someone has been sucking on the pipe for too long :D:D:D:D
[doublepost=1549325024][/doublepost]UPDATE

I haven been able to remove the artifacts and errors :D:p The Cleaning did the job, but I will still replace the damaged capacitors! And also upgrade the RAM to max and perhaps install a SSD in them both (if possible).

When you say "the cleaning did the job", what exactly did you clean? The CPU heatsink/fan duct, the fans after removal, or both?
Regardless, on your photos post #1, I can see 9 defective caps, and on photos post#39, 5 caps defective. So those caps on both motherboards are potential ticking time-bombs, and even if you have a good screen image now it's only a matter of time before that becomes problematic again. To avoid a further tear-down in a few year's time - and these are not particularly nice iMacs to work on for motherboard removal - change out all 25 or 29 caps depending on the model. Fwiw, I dislike working on the G5's, but love working on the iMac G4 - perhaps my favourite of all.:)

The black cable you mention does look as if it's the HD thermal sensor connector. The sensor should have been swapped across from the original HD, (iFixit step 24 details it well).

Don't forget to change the PRAM battery (CR2032) whilst inside - a doddle compared to replacing the capacitors.
Please post back on your experience of changing them.
 
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I have the PowerMac8,2 model. I bought it off a customer that came in to recover data from it for about 25 bucks (I think it was $25, that was June 2018 so my memory might be a little bit hazy about the details)

I asked my good buddy with much, much better soldering skills than me to replace the completely annihilated caps (the machine still booted to the OS with them!).

Unfortunately, even after replacing the caps the machine had garbled video. My buddy reflowed the Radeon 9600 GPU in it (I know, I know, it's going to die anyways) and it booted up just fine as you can see. I have a few spare Radeon 9600's so in the case something happens again, a BGA reball is up on the horizon with a new chip :) I also swapped in new thermal pads from Arctic and a fresh glob of Arctic thermal paste :) It happily chimes every time.
 

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When you say "the cleaning did the job", what exactly did you clean? The CPU heatsink/fan duct, the fans after removal, or both?
Regardless, on your photos post #1, I can see 9 defective caps, and on photos post#39, 5 caps defective. So those caps on both motherboards are potential ticking time-bombs, and even if you have a good screen image now it's only a matter of time before that becomes problematic again. To avoid a further tear-down in a few year's time - and these are not particularly nice iMacs to work on for motherboard removal - change out all 25 or 29 caps depending on the model. Fwiw, I dislike working on the G5's, but love working on the iMac G4 - perhaps my favourite of all.:)

The black cable you mention does look as if it's the HD thermal sensor connector. The sensor should have been swapped across from the original HD, (iFixit step 24 details it well).

Don't forget to change the PRAM battery (CR2032) whilst inside - a doddle compared to replacing the capacitors.
Please post back on your experience of changing them.

I cleaned both iMacs a lot, but I will clean every single component in them as I receive my capacitors from my supplier. The second iMac with the 5 cap replacement really needs extreme cleaning as it is filthy to put it lightly. After inspecting the caps I could see on the older model that it was only the 5 x 1000uf 16v 105 caps that needed replacement. On the other board they were all 1800uf 6.3v 105 caps and there were 9 caps that needed replacement. I was actually thinking about buying a SSD for them both and replacing the aging HDD in these. However, I will buy the SSD's after replacing the caps on both. Also, I was thinking about cleaning and replacing the thermal paste on both machines - both CPU and GPU. I also inspected the battery, which I resume was a CR2032 (if I remember correctly). I will also replace both of these.
[doublepost=1549722097][/doublepost]
I have the PowerMac8,2 model. I bought it off a customer that came in to recover data from it for about 25 bucks (I think it was $25, that was June 2018 so my memory might be a little bit hazy about the details)

I asked my good buddy with much, much better soldering skills than me to replace the completely annihilated caps (the machine still booted to the OS with them!).

Unfortunately, even after replacing the caps the machine had garbled video. My buddy reflowed the Radeon 9600 GPU in it (I know, I know, it's going to die anyways) and it booted up just fine as you can see. I have a few spare Radeon 9600's so in the case something happens again, a BGA reball is up on the horizon with a new chip :) I also swapped in new thermal pads from Arctic and a fresh glob of Arctic thermal paste :) It happily chimes every time.

Wow! The first picture really looks bad! Did changing the caps not have a impact at all? How did your friend reflow the GPU? With a hot air station? In the oven or using a torch? :)
 
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I cleaned both iMacs a lot, but I will clean every single component in them as I receive my capacitors from my supplier. The second iMac with the 5 cap replacement really needs extreme cleaning as it is filthy to put it lightly. After inspecting the caps I could see on the older model that it was only the 5 x 1000uf 16v 105 caps that needed replacement. On the other board they were all 1800uf 6.3v 105 caps and there were 9 caps that needed replacement. I was actually thinking about buying a SSD for them both and replacing the aging HDD in these. However, I will buy the SSD's after replacing the caps on both. Also, I was thinking about cleaning and replacing the thermal paste on both machines - both CPU and GPU. I also inspected the battery, which I resume was a CR2032 (if I remember correctly). I will also replace both of these.

NOTE: Don't make the mistake that many do in just changing out the ones that are bulging or leaking.


@MacGuyFrom1831 I recommend to read cooperbox's full post :) He has knowledge to share...
 
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@MacGuyFrom1831 I recommend to read cooperbox's full post :) He has knowledge to share...

Hi Traace :) I've read all the comments many times. I've read on Fixit that changing the ones that are fine is a waste of time as those surviving are good and managed the heat and such as opposed to those that did not and are defect.
[doublepost=1549723691][/doublepost]
When you say "the cleaning did the job", what exactly did you clean? The CPU heatsink/fan duct, the fans after removal, or both?
Regardless, on your photos post #1, I can see 9 defective caps, and on photos post#39, 5 caps defective. So those caps on both motherboards are potential ticking time-bombs, and even if you have a good screen image now it's only a matter of time before that becomes problematic again. To avoid a further tear-down in a few year's time - and these are not particularly nice iMacs to work on for motherboard removal - change out all 25 or 29 caps depending on the model. Fwiw, I dislike working on the G5's, but love working on the iMac G4 - perhaps my favourite of all.:)

The black cable you mention does look as if it's the HD thermal sensor connector. The sensor should have been swapped across from the original HD, (iFixit step 24 details it well).

Don't forget to change the PRAM battery (CR2032) whilst inside - a doddle compared to replacing the capacitors.
Please post back on your experience of changing them.

The older Macs were much better and easier to work on. Apple just made things worse for repair on purpose. In regards to my G5's I think the older one is fine in regards to the GPU, but the newer one might have some GPU problems and might require a reflow/reball. Should I just reflow it as I am replacing the caps? Or should I wait and see how it does afterwards? I was thinking this after reading your comment in regards to the difficulty of removing and working on the logic board.
 
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Hi Traace :) I've read all the comments many times. I've read on Fixit that changing the ones that are fine is a waste of time as those surviving are good and managed the heat and such as opposed to those that did not and are defect.
[doublepost=1549723691][/doublepost]

The older Macs were much better and easier to work on. Apple just made things worse for repair on purpose. In regards to my G5's I think the older one is fine in regards to the GPU, but the newer one might have some GPU problems and might require a reflow/reball. Should I just reflow it as I am replacing the caps? Or should I wait and see how it does afterwards? I was thinking this after reading your comment in regards to the difficulty of removing and working on the logic board.
Put it this way. The caps were a frequently known problem. If it's just the caps which are problematic, the change of a complete set (available in kit form) should provide the cure.
A GPU fault cannot be ruled out, but from all that I've read in the past it wasn't the main cause of many problems reported. Plus if you reflow it, consider it a temporary fix only.
As the logic board has to be removed to change the caps, that I guess would be an ideal occasion to reflow the GPU, although not something I would do before changing the caps - that we know are defective. GPU reflow is a controlled procedure, and frankly even if done very carefully can be very hit & miss.
 
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Put it this way. The caps were a frequently known problem. If it's just the caps which are problematic, the change of a complete set (available in kit form) should provide the cure.
A GPU fault cannot be ruled out, but from all that I've read in the past it wasn't the main cause of many problems reported. Plus if you reflow it, consider it a temporary fix only.
As the logic board has to be removed to change the caps, that I guess would be an ideal occasion to reflow the GPU, although not something I would do before changing the caps - that we know are defective. GPU reflow is a controlled procedure, and frankly even if done very carefully can be very hit & miss.

Exactly! The correct thing would be to replace the caps then test the machine. If the problem persists then reflow/reball the GPU. However, if I am very unlucky than the problem would be the VRAM chips.... That would be unfortunate to put it lightly.
 
Those wondering whether or not these iMacs can be used on for the internet and security risks you can download TenFourFox, which is a fork of Firefox for PPC machines.
 
UPDATE

I have finally received all of my parts and I have started with the disassembly process. Everything is going fine and I am being very careful. However, I have this SATA power plug (perhaps), which is resisting to come off. I am not using force as I don't want to break it. Does anyone know how to get it unplugged properly without damaging anything please? It has already damaged to of my nails :( :)
 

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