7300/200 Lights on but nobody's home

[ImmortanJoe]

You might remember my Performa 5200CD thread? Or not. it doesn't matter. It was one of two computers I purchased. The other is a 7300/200. Turns on and off with the front power button. Turns on with the keyboard. Power LED lights. Not much else.

So far I've tried a few things in no particular order. Cleaned the motherboard (including with de-mineralised water) and all connectors. Replaced heatsink paste on the CPU card. Re-capped the motherboard (yes I did the underside too). Tried leaving it running for a bit to see if it "wakes up" as some borderline Macs do (It didn't. The PSU also failed). Repaired the PSU. Tried powering up with every combination of RAM, VRAM, and cache board that made sense, With drives without drives etc. With and without CUDA battery. Probably other things. I don't remember. I'm out of ideas. However I did just receive a neat little single channel digital scope from China. My old CRO is a long way away and it's been hard making progress without it so I had to do something. Also all the PSU voltages are good.

So... ideas?

A note on the 5200CD. I haven't given up on it. I was just waiting for the scope because I'm stuck with that too.

 

[GRudolf94]

It's not uncommon for the CPU card slots to be cracked on some machines that use CPUs mounted like that. Maybe check the ends of the slot.

 

[ImmortanJoe]

It's not uncommon for the CPU card slots to be cracked on some machines that use CPUs mounted like that. Maybe check the ends of the slot.

This isn't surprising. I know the plastic air channel thing or whatever it's meant to be has a notch to support the CPU card but the whole thing isn't exactly confidence inspiring. I'll have a look later on to see if I can find any evidence of cracking on the socket. Can you think of anything else I should look for while I'm at it, because I'll probably pull the motherboard out to have a look.

 

[Byrd]

Also recently picked up a couple of 7300 machines; a 7300/180 and 7300/200; both exhibited the same behavior, no chime bar some static on the speaker. PSUs checked out fine. For both, it was the CPU daughter card and a stick of bad RAM in each. Amusingly switching the CPU daughter card on both Macs resulted in them both working! Presume if poorly stored, or slight sag of the heavy CPU card long term weakens the CPU connector over time. With some deep cleaning of the CPU connector, daughter card edge connector and positioning it just right seems to resurrect these machines.

 

[ImmortanJoe]

There's no cracks or distortion in the CPU card socket