PM 8500 no boot

[plb007]

Hi, 

I've been reading passively this forum for years. But now, I really need to exchange knowledge regarding one of my problem. 

I have a PM8500 (WS8550 to be exact), I forgot to remove the battery and that ends with a little corrosion on the motherboard. No startup sound, no video, disks are spinning, but nothing. I clean the motherboard as much as I can with no result. I ended up buying a new motherboard (cheap), switching everything necessary with no more result. It leave me the PSU or the processor card. What can be the problem ? Can I use processor card from 8600 or 9600 or even 8100/8200 ? Which processor cards are compatible with ? I have a lot of old powermac on storage that can help the diagnostic. 

Any idea ?

Thanks, 

plb

 

[NE555]

There are some obvious things that come to mind.
Like the way the Memory SIMMS is arranged. When I had the memory SIMMS in the wrong order, then exactly what you described would happen.
Download the service manual for your Computer and arrange the memory the way it is described there. Actually start with the minimal items back on the Board and see if it comes back on.
Also buy a fiberglass pencil and clean the contacts with it.
Are the VRAM SIMMS in the right order?

 

[AwkwardPotato]

Also, make sure the processor card has clean contacts and is fully seated in the slot (it takes a lot of force to put in all the way and this got me on my 8500).

8100/8200s don't have processor cards and AFAIK the later 8600/9600 ones aren't compatible.

 

[NE555]

true... although I found that clean contacts slide a lot easier

 

[plb007]

Hi, 

Thanks for your replies. The issue was a bad processor card. Earlier 8600's can use 8500's processor (And the opposite too). It seems that processor card can also gone bad with time (like capacitors on older motherboard). 

 

[NE555]

So did replacing the capacitors and new heatsink paste then remedy the situation?

 

[plb007]

Hi, I didn't try to replace capacitors on the processor card. I just swap with another one. They are very cheap on eBay ... But I wonder if the captors are the cause of the problem. They look clean but I guess they can leak too. 

 

[NE555]

Do you still  have that card?

 

[AwkwardPotato]

Come to think of it, I have a 604 card and some of the SMD electrolytics right next to/under the heatsink seem to be bulged on top. The card still works, though.

 

[plb007]

I still have the card, I can once try to replace the capacitors. 

 

[jimjimx]

Can I use processor card from 8600 or 9600 or even 8100/8200 ? Which processor cards are compatible with ? I have a lot of old powermac on storage that can help the diagnostic. 

 The 7300, 7500, 7600, 8500, 8600, 9500 and 9600 all used the same processor slot with different processors on daughter cards. I’m not sure if they can all be swapped around, but they all had G3 upgrades for them, or G3 zif carriers, which you would be able to drop in a G3 zif you had, or bought. 

 

[Unknown_K]

The later 8600/9600 CPU with cache on board instead of the separate cache stick are probably not swappable with older boards.

8100 series CPUs are soldered on I think.

Make sure to hit the CUDA switch when swapping CPUs and make sure they are fully seated or the machine acts like it is 100% dead.

 

[NE555]

Come to think of it, I have a 604 card and some of the SMD electrolytics right next to/under the heatsink seem to be bulged on top. The card still works, though.

Then it's time to replace those capacitors