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Yet Another Dead Beige G3 Desktop

mattsoft

Well-known member
Picked a beige G3/266 desktop some time ago, listed as working, however when I plug it in, it is dead.

The fan on the PSU powers up, but the power LED does not, no power chime, the HDD or CD drive do not power on either. Bad PSU?

So time to start troubleshooting...

  1. Measured the voltages coming off of the PSU while the G3 was powered on. All voltages are nominal. Check! Strange that the HDD won't spin up with good power (scratches head).
  2. Installed fresh battery. No change.
  3. Removed and reseated the CPU, ROM DIMM, memory, voltage regulator board, and personality card. No change.
  4. Removed the HDD and CD from the IDE bus and this time, but left power plugged in. When powering on this time, the HDD and CD had power. Huh...so being on the IDE bus caused them to NOT power on, but being off the bus they powered on fine. The G3 still did not post -- no chime or power light, but some change from the devices.
  5. Re-cap time! I replaced all the SMD capacitors on the logic board. They were pretty dry and left little brown turds of dried up electrolytic behind. But the board looks really good. Continuity on all pads is good. Cleaned the board with isopropyl and tried again. No change, still dead.



So I'm stumped on this one. The only caps I could not change were the 4 680uF caps on the voltage regulator -- I don't have any replacements in my stash. So I've ordered some more supplies from DigiKey and will replace those this week and see. The service source for this model says to replace the voltage regulator for symptoms like mine, so maybe this is the problem. 

 

jimbojones

Active member
Try with the HDD and CD unplugged from the IDE bus AND power and press the CUDA reset. The IDE bus on mine is very dodgy and sometimes causes it to not boot.

It doesn't need a battery on the motherboard to boot.

Test the PSU to make sure it's outputting the right voltages. Again, I think the PSUs in these machines can be a bit weak, so removing the HDD and CD may help.

 

androda

Well-known member
Also, leave it for at least a minute or so. They can be very slow to boot up sometimes (not sure why).
Mine does this too. Sometimes starts right up after pushing the power button (meaning the display comes alive immediately and things proceed as usual). Other times, black screen for a good 30 seconds. Unsure of the cause, but seems fairly benign given that the machine keeps booting properly despite the delay.

I need to replace the caps on all my beige G3 mobos. Going to have a giant list of caps to order, doing several motherboards (G3, duos, spares, etc) and power supplies and stuff all all once to save on shipping.

 

mattsoft

Well-known member
UPDATE! I replaced the 4 caps on the voltage regulator board and the G3 now chimes and boots to a ?. Hurray! Now to fine a boot disc and HDD...

 

mattsoft

Well-known member
More progress to report. System is working well. Booted an 8.6 CD on the internal CD-ROM, reformatted and installed onto the HDD. Everything is working fantastic. Now to clean the FDD...

I wish the plastics on these weren't so brittle. They are fantastic machines to work on, except for the plastic bits inside. Sigh.

 

rolopolo

New member
Same problem here. Power supply fires up but no green power light. Power good says 5v. Replaced the VR board with one that the seller claims working. No go. Oh well.
 

Unknown_K

Well-known member
I pulled out a Beige G3 a few weeks back and the plastics (desktop model) are turning in the same brittle plastics in my 7500's.

Back in the 2000's when I snagged a few G3 desktops I had one unit that would not boot no matter what I swapped from other units and I never did figure it out. There are a ton of capacitors on those boards and I am no mood to recap them yet.
 

demik

Well-known member
The VR board is possible issue with theses, you need the jumper block as well. Some versions didn't work at all with power hungry CPUs (think 300 MHz+ or upgrade cards)
 
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