Troubleshooting a Quadra 840av

[James1095]

It would be handy to have lists of capacitors in the power supplies as well, maybe with notes indicating the most common failures. It would save the time of having to tear the thing apart once to make a list of capacitors and again when the parts arrive.

 

[Trash80toHP_Mini]

That's a great idea. I made an ill-fated start at just getting the model specific PSU specs documented in pictures, but never got around to working on it . . .

This'd be handy for shopping fo ATX replacements . . .

http://68kmla.org/forums/viewtopic.php?f=29&t=13039&start=0

. . . but combining it with the kind of data you're suggesting would be awesome.

 

[luckybob]

Finally got the caps from Mouser! I ordered a nice pair of tweezers and boy was I glad I did!

I'm not going to make this a long story. But the end result is, the board is dead. After replacing all the caps, I powered the board and the area of the board near the ADB connector catches fire. It seems that this area of the board is responsible for turning the system on and off. xx( In the space of 3 seconds, the cap I replaced burned up, the traces near it burn off, and the power regulator glows and makes a FOOF of magic smoke. (the cap WAS installed correctly) I put the logic board in a box, sealed it with a tear and put it on my shelf. (i pulled the cpu) I was going to take pictures but I'm just too sad. :disapprove:

So, I'm in the market for a 840av logic board. Anyone got one for sale?

 

[uniserver]

Sounds like you had the same bull crap luck I had with my internal SCSI cable in a PLUS adventure, It's ok because mcdermd to the rescue, my plus was a upgraded 128k anyways. We're going to do a trade, in return he is hooking me up with a Very Nifty 128k board, I am going to rig up some dip switches to it, So I can toggle back and forth between 128ke and 512ke. Also is including a Macintosh Rear, So i'm putting it back to the way it was anyways, He's is hooking me up with a PLAT Plus aswell, so I can still have a working plus in my collection

 

[mcdermd]

Uni - check this thread: viewtopic.php?t=2042 and this post: viewtopic.php?t=2882#p131886

 

[uniserver]

viewtopic.php?t=2882#p131886

Swaheeeeeeet!

i can make a 4 in 1 Mac!

 

[mcdermd]

I have the SN74LS253N mux chip I can toss in if you want to research making your own mini-mux board. You'll need to figure out which legs connect to which of the five holes on the logic board and it's just a couple of resistors after that, I think.

 

[uniserver]

sounds good man! thank you.