Quadra 840AV problems, need help

[MacNostalgic]

Hmm,

it should be try, because after washing (at this moment the board was almost dry), I have put the board in the baking oven at 125°F for about 30 minutes. Then through the night I laid the board up side down til this morning.

Parameter RAM did work. I tried it four times a row.

Power on from keyboard works also.

The speaker connector I can only put in one direction.

Starting from CD doesn't work. No reaction.

Good thing is, the Mac recognize the disk (not CD), because he eject it and shows a "x" on the screen.

I think, now it's time for resoldering the capacitors and then to check the power supply with a multimeter, but for checking the voltages I need further instruction.

It can't be that much damaged, I think.

 

[CelGen]

All bets are off on a reliable troubleshoot until the leaking capacitors are replaced. This always applies to any mac which has a currently known issue with leaking capacitors. The Classic II and SE/30 in particular.

 

[beachycove]

Do you know anyone from whom you could borrow a working 3.5" SCSI hard drive with an installation of System 7.5-8.1 for 68k?

 

[MacNostalgic]

Hi guys,

This forum is really really great. Thanks for all the input!

I have talked right now to a guy here in germany. He has two working 840. I think I will send it to him.

I have lots of software and can't used it :-(

And I have also a Radius Thunder IV I want to use. But this card was also sold as "damaged"

But first I want a working 840

Stay tuned

 

[Byrd]

I don't understand what you're trying to do. If you're getting video output/a flashing disk icon/chime, that suggests you do NOT need to replace the capacitors, but undertake normal troubleshooting routines to try to get the machine to boot. Same goes with the power supply - the Mac appears to work, you don't need to pull it apart.

Why put your precious Mac at risk of complete failure when simple troubleshooting may be all that you need? And lastly - don't put things in the oven for a little while to dry them, that's kind of crazy.

JB

 

[beachycove]

I agree. First things first.

Try removing the Parity jumper on your CD drive.

 

[Bunsen]

If you're getting video output/a flashing disk icon/chime, that suggests you do NOT need to replace the capacitors, but undertake normal troubleshooting routines to try to get the machine to boot.

Exactly. Why every single help request - not matter what it is - starts a chorus of "Wash the board! Replace the caps!" I'll never know, when there are simpler and safer things to try first.

And RFI interference WTF? Just no.

The flashing question mark [?] means that the Mac has completed its self test and is looking for a System folder to boot from. So - work on getting the CF (or some other disk) booted.

No chime:

This is not in itself a fatal sign. Sound output is one of the first things to go wrong as capacitors fail. So, while it may be a sign that there is a bad cap or two, it does not mean that there are severe problems with the logic board.