Dual G4 800 Quicksilver doesn't power on

[bawalker]

Hello all,

I purchased a Quicksilver Dual G4 800mhz tower that was used but in very good condition and very working order. After about 3 weeks and a complete cleaning out/dismantling of the case I powered the system back on, and it worked. I used it for another week before I went to swap out the DVD-RW super drive. ALL I DID WAS UNPLUG THE IDE CABLE and the system stopped powering on. The fans would not spin, nothing would start. When I press the power button all that happens is the power button lights up for a breif second and then goes out.

I have done everything imaginable at this point to cure the problem. I reset the PMU per apple instructions. Didn't work.

I replaced the memory thinking maybe something went bad there. Didn't work.

I replaced the video cards, didn't work.

I replaced the logic board. Didn't work.

I purchased and replaced a used but working power supply. Didn't work.

I dismantled the entire system again to make sure it wasn't grounding out. I put a piece of antistatic bag under the logic board, rested the logic board on the table. Plugged in the psu, speaker, power/reset cable, put the cpu/heatsink on. Didn't work.

The ONLY thing I haven't replaced as of yet is the CPU, but I really don't want to spend another $80 on something that may not work. I don't even know what is causing this problem. Apple's documentation says 'replace the logic board'. I did that and that didn't even solve the issue.

Help!!

[mattsuzu]

replace the motherboard battery with a brand new1 dude, i'd almost bet a testicle on that being your problem

let mw know how you go

[bawalker]

Actually I solved the problem the other evening. Come to find out that the red wire from the case fan in the mac had gotten slightly cut and was touching the metal case causing everything to ground out. I taped the wire and all is fixed.

[mattsuzu]

LOL lucky i said i'd ALMOST bet that :P

i've had a few G4's display teh same symptoms with a deam logic board battery.

[Tinpusher]

Seems this is my problem!

2 questions:

1. How do I replace the logic board battery?

2. How do I prevent this from happening again?

[nixgeek]

The battery on Mac should look like a half-size AA battery. You can buy replacement batteries here:

http://www.welovemacs.com/welomabawi1.html

As far as it happening again, this happens to all computers, even PCs since they also have an internal battery. The thing is that since Macs have longer staying value, people keep them longer than PCs....long enough to experience the death of said battery (which usually lasts for about 4-6 years). I had a Mac clone (Motorola StarMax 4000) from 1997 that had it's internal battery die just last year, so each battery is different.

For the record, I've kept some PCs around for a while, even long enough to have the internal battery die as well, so yes I know from experience.

[LeighRK]

I too have a dead QS2001 DP800. Originally it became suspect and would randomly (generally after a minute or so) turn itself off and then later (20 or 30 minutes later) would spontaneously re-start. Then one day - just dead - nix, nada, nothing. No boot, no logic board light, not a whisper. The power on light would go on briefly after being pushed, but would not stay on. No power, no chime, no fan, no power board light(s), no HD activity. I have replaced the battery, reset the cuda switch, replaced the power supply - with a brand new Apple one - no change. I am not sure what else to change - there has been no previous trouble with HD's, DVD Drives etc., and they don't seem to be the culprit here. The only other 2 components left are the Logic Board and Processor(s). Anyone out there know what to try?

[DeltaMac]

That's right, the two components left are the logic board, and the processor. Apple's service manual seems to point to the processor.
You can try simply reseating the processor, and I would try removing everthing that you can remove. vid card, memory, PCI cards, if any, modem, airport card - anything that could be removed from its connector. reinstall everything, but leave any PCI cards out for now. If you still get nothing, you should have tested at an Apple auth service. they can verify some power supply voltages, etc, and may have other spares, like a processor that could be tried. Repair will get a little expensive if you have to actually replace a processor or logic board.