Powermac G4 QuikSilver - no display on boot

Hi,
I am a bit new to retro Macs. A friend asked to see if I might be able to fix his G4.
There is no display output from SVGA, or DVI to a known working dell monitor. There is no beep, or bing on power up. There is a small lit red led on the motherboard. I do not have a Apple keyboard to reset pram(nvram). The fans and HD's (4) all spin up. The ram sticks were tested in a windows machine and they work.
Shortly after boot the cpu heat sink gets very hot to the touch. I pulled out the PCI card for the extra 3 HD's, no change. I swapped the video card to another mac card, no change.
After I get a keyboard, suggestions on what to test next?
Thanks

Can you ask the friend when this G4 last worked properly? Hopefully this isn't a computer that was sitting somewhere for years unloved...and now has been pulled out of "moth-balls". If it has been a while...memory's get fuzzy. Sometimes the issues that caused the computer to be taken out of service are forgotten (but can be great info in helping guide us to getting it woeking again).

Thanks,

- Nick

Thanks for a quick reply!

He says it was last working about 2 months ago. He remembers powering down 'properly'. He went to power it up last week and got no display. He also said that his dog tipped it over a few weeks ago. I'm not sure I believe that. This machine is heavy. But it may have received a good bump.
I did check for any loose connections. all was tight. nothing usual. Motherboard battery has good voltage. He said he replaced it about 1/2 year ago. Inside is clean, no dust.

Ok...great info to know.

If you've confirmed good operation of the:

- RAM
- Video Card
- PRAM battery
- Monitor & cable are known to be good.

Is it clean inside (dust, dirt, etc. in the fans)? Do the fan(s) work?

Can we assume the computer was working after it was knocked over? lol

No "bing" or "gong" sound on startup is an indicator of something (this should almost always occur with a fully functional computer)...even with stuff like HD, RAM, removed.

How about this...could be the power supply. An old computer like this...power supply could be weak. Maybe too weak to power the video properly.

HTH,

- Nick

Great info from Nick. Just one more thing. If it is the power supply, Apple uses their own proprietary power supply. do NOT try and plug in a PC power supply as all the rails are on different pins!!!

dtravis7 said:

Great info from Nick. Just one more thing. If it is the power supply, Apple uses their own proprietary power supply. do NOT try and plug in a PC power supply as all the rails are on different pins!!!

Click to expand...

LOL, that should be fun Dennis... watching the smoke and smelling the burning capacitors.

Thanks again for all the quick replies. Very helpful!
Yes it could be a PSU issue. This unit has 4 (four) HD's in it. They have been there for a long time. All that extra draw certainly has stressed the PSU over the years.
As posted above, HD's and fans spin up fine. No Dust in the case.
How to measure PSU output in a G4? I assume it must be connected to the MB and powered on. What pins to test with a trusty multimeter?
If the PSU is dying, what would be a good replacement? I could recap it myself, but I always buy the wrong parts(right values, wrong size. I've melted traces, blow resistors & caps with my past recap attempts)

Pinouts here. There are many systems listed, scroll down till you find Quicksilver G4.

http://www.smps.us/power-connectors.html

Instructions for taking it out.

https://www.ifixit.com/Guide/Power+Mac+G4+Quicksilver+Power+Supply+Replacement/2053

I just tested the PSU under load.
All the 5v lines show 5.1 to 5.24 the 3.3v lines show 3.34, the 12v shows 12.3 The 25v show 25.53
Are these number within tolerances? Most all are above the numbers shown from the top link in post 8

Anyone have some additional thoughts on what might be wrong with this G4?

Anything helpful here or at least some of the LED info or diagnostic stuff???

http://tim.id.au/laptops/apple/powermac/powermac_g4.pdf


Or here:
https://www.google.com/search?clien...4+QuikSilver+LED+diagnostic&ie=UTF-8&oe=UTF-8






- Patrick
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KLund1 said:

Anyone have some additional thoughts on what might be wrong with this G4?

Click to expand...

You sound pretty knowledgeable...so I know you probably already know what I'm going to say. You've done some great troubleshooting & parts swapping so far. Assuming nothing was damaged when the dog knocked the computer over...seems like some of the only things left to swap are the power supply & the logic board (and remotely a possible a bad cable).

- Nick

Shortly after boot the cpu heat sink gets very hot to the touch.

Click to expand...

Any chance the possibility of the thermal paste not working properly??

But I wouldn't think that could cause a no-boot issue and just a wild thought.

I had one of those Quicksilvers before I got one of the last of the MDD "dual boot" models that's still around here somewhere.





- Patrick
======

Ok, back to this. I was distracted, I mean working on 1200XL project.
The links from post 11 were a bit helpful. Followed the troubleshoot section. Still no boot.
I did find that the heat sink was on backwards. A corner was up on one of the little black boxes, so there was little cpu contact. I do not know how long it was like that. Probably happened when 'the dog' knocked it over. I never had it on long, but my friend may have. The CPU may have overheated and is not working. But the motherboard should still beep 5 times if the cpu is bad according to troubleshooting guide from post 11. I pulled the ram, and powered up and did not get any beeps either. All this with nothing attached, video, HD, KB. One other thing I noticed is that teh power light does not stay on. It goes off shortly after power, up, and will light when I touch it.
Any other thoughts, or is this now a write-off?

If it's any consolation. This is a 16 year-old computer (2001/2002). If this computer was working 100%...lucky if it's worth $10-$20 (if you can find someone to pay it). Maybe could sell the power supply on eBay for that much as well (if it's working). If you can't get it working...it's probably good for parts to someone.

Not saying you shouldn't try to get it working as a pet project...or as a "I'm not gonna give up on it" sort of thing. And it's possible your friend may need it to run really old software...open up really old documents...or still have 2.5" floppy disks, or CD-ROM's that this computer reads.

But at some point if it's busted it's busted. If the friend needs this computer for something...probably a lot easier to go shopping on eBay and purchase an exact replacement (or very close)...for a pretty low price.

- Nick