Power Macintosh 7100 Not Starting with Case On?

[cjbriare]

Hi all,

Been a while since I've posted here, but I've ran into an issue I have not seen before and was wondering if anyone else has, as I am completely stumped

Power Mac 7100/80av with the av card in the PDS slot. The card itself seems too short to meet up with the slot on the back of the case, however it still functions. When I put the top case on, it seems to rest on top of the PDS card slightly.

This will not allow the machine to boot, no chime even--yet boots like a champ when I remove the top case. I pushed in the top case from the bottom and that seems to have temporarily solved it, but sticking a monitor (or anything) on top of the unit will move the PDS card and cause it to crash.

I'm thinking the card not being seated securely in the slot may have damaged it or the logic board, and the top case might make it unseat or fail some way...no idea.

Any ideas?

 

[MacTech68]

A few pictures of the inside might help to spot the problem. These chassis can be a bit odd in places when re-assembling.

 

[cjbriare]

A few pictures of the inside might help to spot the problem. These chassis can be a bit odd in places when re-assembling.

I will post some when I get home

 

[retta283]

Have you tested this anymore since your last post? It seems like the card is just too tight against the case that it's causing it to come unseated and the system freaks out. it's odd to me that a PDS card would cause a crash, is there anything else you can put in that slot to test?

 

[cjbriare]

Sorry for the absence, I had been putting off looking into this for some less exciting chores...

I opened the case and noticed that the logic board was seated a bit aways from the back of the the chassis, a lot of the plastic notches became brittle and broke off in some areas so the board is not totally locked into the case.

That being said, when I removed the entire logic board, there was a screw underneath it, right under where the PDS slot is (!) No clue where this is from, I had no screws missing anywhere and have never removed the logic board before this. Anyway, I put it all back together and now everything seems fine, oddly enough.

I did have one casualty: my reset/programmers switch broke apart when removing it. RIP. Thankfully I had one spare.


There is still quite a bit of play on the PDS card in the slot, is that normal? (see video) With the top case on there is less play to it, but still am unsure. Could also just be the age.

Thank you all for the replies thus far, I'll post if anything happens.

 

[MacTech68]

That's pretty normal for this chassis. You'll notice the rear panel is probably not exactly perpendicular to the table. Once the top case is on and the encapsulated screw in the top case is tightened, it all comes together (mostly).