G3 iMac 400 power troubleshooting

[RickNel]

I've been given a strawberry G3 iMac 400/DV that is nice and clean but won't power up. So far I've replaced PRAM battery and tried pushing the CUDA switch. On one occasion the power-on button flashed for less than a second, but generally nothing fires up. I do hear a pop in the speakers, which suggests there is some power on the board but not enough to boot. Display remains dark.

Any suggestions on a troubleshooting checklist? Could this be a caps issue?

Rick

 

[bibilit]

Any suggestions on a troubleshooting checklist? Could this be a caps issue?

Yes can be, you can probably find the service manual online, it's pretty well done... will help troubleshooting any issue.

 

[RickNel]

I just saw Didius' thread on what sounds like very similar G3 problem.

http://68kmla.org/forums/viewtopic.php?f=13&t=21863

A great save by Didius

Looks like I have a major re-cap to consider. This "free" G3 iMac could end up costing $$$. But it is a pretty machine, pink and rounded, and hard to resist its charms.

Rick

 

[CC_333]

It might be easier (and less labor intensive) to just replace the analog board with a known working pull from another iMac (such as one who's CRT is smashed and/or who's plastics have crumbled.) How you choose to proceet is pretty much up to you, though.

Anyway, however you choose to proceed, I wish you luck!

c

 

[didius]

The hard part is cracking it open and getting the PAV board out... Replacing the caps or replacing the board is just a choice...

I found replacing the caps was pretty easy. There are a lot of them, that's true, but hey isn't reviving these macs a fun hobby?

It takes some time, but i found replacing the caps easier then getting the PAV-board out and back in...

 

[RickNel]

To repair or replace is always a fair question, but location is a big factor. I see working G3 iMacs advertised for $5 in California, but in my location to get parts from anywhere adds $40-50 freight to the cost, even for a logic board, and working units are rare locally. Nobody seems to bother parting out G3 iMacs in Australia.

The main risk in starting a major re-cap is that I could get to the end of it and then find the problem was deeper, say a failed PMU/CUDA chip. Anyway, while I wait for a logic board or working iMac to turn up at reasonable cost, I'll disassemble this one and see if I can see any evidence of other probs, before investing in the re-cap.

Rick

 

[didius]

Somewhat an identical situation in belgium

Keeps us updated! Perhaps you could try the pin-readout I posted?

 

[RickNel]

I'll be following your experience closely, but not necessarily quickly. Yes, I'll report back when I make any progress.

Rick