End of the line for my Q800?

[IIfx]

I regret ever buying a Newer Tech MacClip Jr. Ever since I had a failed attempt at using one the whole system hasn't been right since. To put things short, the MacClip fell off of the clock oscillator while the system was on. It just popped off on its own! This of course caused havoc as the system clock suddenly dropped. The end result of this incident was a fried SCSI controller on the original logic board. So I swapped over all of my components to my spare logic board, minus the MacClip.The problems continue there.

At first everything seemed to be OK, but then my hard disk died. Ok, no problem, just swap in another one. The system wouldn't detect it, but my G4 can see the drive. After doing some dancing around, I finally got a CD of System 7.6 to see the drive. Formatting began, and took eons. The system eventually just locked up. So I took the drive out and put it back in the G4. It initializes there no problem. I bring it back to the Quadra and try booting from HDT PE. That seemed to work, until it crashed with a bus error bomb. I removed all of the RAM and tried again. Booting was successful but my version of HDT is on OS 8 and needs more than 8mb of RAM to run.

Ever since that successful boot the Quadra has not been able to see anything on the SCSI bus at all. The built in CD drive is seemingly toast.

Is it possible that I have fried two logic boards in a row? Perhaps it's time to look into replacements for this machine. It's a shame as it was my primary workhorse for 68k stuff. Now it's a paperweight.

Any ideas? I have already done the obvious. Reset the PRAM, restated all connections, etc. Caps are solid state so that shouldn't be an issue.

 

[AlpineRaven]

Sounds like it needs recap. Has it been re-capped?
Cheers

AP

 

[IlikeTech]

Look at his last line lol.

 

[beachycove]

Can you try another power supply? Or swap the logic board into a Iivx, 7100, etc., to see if the problem persists with one of those power supplies?

 

[IlikeTech]

I might be able to hook you up with a Q650 logic board and the ATX adapter I made for it.

 

[IIfx]

The caps are solid state tantalum and are unlikely to be bad across two logic boards.

I will try swapping it into a PM7100. Perhaps my AppleCD300 internal drive went bad from the overclocking fail of the MacClip when it nuked the SCSI controller.

Parts that could be to blame:

Logic Board

The 68040 itself

All SCSI devices that were connected to the bad board

RAM

PSU

@ILikeTech: Thanks for the offer. If I can’t get one of my two Q800 boards running the Q650 one would make for a quick fix!

 

[beachycove]

I had a Quadra 950 here at one time that I was fiddling with, managing to connect together the wrong pins of the Molex power connection when adding one of those little m/f Molex extensions (I was adding a drive and did not have the proper power cables, when the pins came out and I put them back incorrectly). Things went bang in one of the drives, magic smoke emerged, and the darned thing wouldn’t subsequently boot. Eventually I gave up and put it away. Then before scrapping and selling parts, I tried one more time, after changing the ram, and lo and behold, up she booted.

All the ram involved subsequently worked, so I don’t think it was to blame. I think the pram got royally buggered up and that it just needed a wee rest to clear. Anyway, it subsequently worked like nature intended, though I had been 99.999% certain that I’d fried the poor thing.

Removing all power for a while, therefore, incl pram battery, might be something to try.