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This has not been a good month for me. First my poor cat Linus is hit and killed by a car last week, and now the Q950 I picked up from our dear Nuvision has died! This Quadra 950, a workhorse at Nuvision Graphics for who knows how many years, is now giving no signs of life, and I don't know why.

 

It all started when I first received the machine from Nuvision a few months ago. The front of the machine had a label on it which read "BOOTS (NEEDS WORK)", so I knew things would be interesting. When I first set it up, it was not booting due to the format of the HDD, also indicated by that label on the front. Attempting to boot into both 7.6 and 8.0 install CDs, I kept getting bus errors; indicated by both a bomb message and SadMac 000F 0001. I popped in a SCSI2SD and after a few attempts to boot, it eventually started working. I had no clue why.

 

It's been a few months since I booted it, and I've moved to a new house, and when I dragged the machine out of the closet a few days ago it worked fine. Then I ordered an Asante MCNB Rev.A NuBus card for the machine, and inserted it yesterday. I got a boot chime, but no video, and eventually death chimes. I removed the ethernet card hoping it would boot, but it wouldn't. After a few power cycles, it began to boot off the SCSI2SD, but when the Mac OS splash screen appeared, I got that "bus error" bomb quite a few times, and a single "illegal instruction" bomb thrown in there as well. Thinking there must be a bad SCSI cable or that the SCSI2SD may have died, I removed them and attempted to boot off the DB25 SCSI port using a CD drive, but kept getting bus errors.

 

After a few more boot attempts, it was just a boot chime followed by a death chime after the RAM test finished, and a couple power cycles later absolutely no signs of life. At around that time I was starting to realize that I would have to gut the machine to troubleshoot. I wound up removing everything: floppy drive, PPC 601 card, a PowerPump overclock kit, and 128MB of RAM, all to no avail. I don't know if the Asante card killed the board, or if the history of bus errors indicates some other issue. I might get an oscilloscope so I can probe the 040 and NuBus hardware to see what's working and what's not.

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My sympathies regarding your Linus.   I lost a cat to coyotes a couple years ago -- still hate coyotes, always will.   They don't belong on land where people live.   Lucy was a sweet cat, a little standoffish, but good natured.

Edited by trag

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most cats are standoffish. I had an evil but lovable one before it died of old age. 

 

As for the Q950. Do you know if the power supply is even any good? or stable? if you have unstable rails, you end up with garbage in = garbage out. 

Edited by techknight

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11 hours ago, techknight said:

As for the Q950. Do you know if the power supply is even any good? or stable? if you have unstable rails, you end up with garbage in = garbage out. 

I was thinking the same. Definitely worth checking.

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I will be checking the PSU!

 

I removed everything, including the motherboard, for inspection; everything looks fine. The scene in here is depressing. I miss my cat.

 

4A621E8F-465F-4C8F-BB54-F13EF373358B.thumb.jpeg.69a30b629ec528609a504ad4f5697ca8.jpeg

DE1EBEDB-D465-4DC8-91E4-84D354CFA8A3.thumb.jpeg.1dc3b8e1141b552a5484a63ecba219a2.jpeg

 

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I'm so sorry about your cat :'(

 

About 13 years ago, we lost several to coyotes. The remainder lived out their years in peace. We have none now, and don't have the heart to get any more (if it's meant to be, one will eventually show up and adopt us as its "pets," but we're not seeking them out).

 

Anyway, back to the Quadra. It sounds like maybe there's bad RAM? But you said you removed it. Hmm....

 

Strange!

 

c

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There's no onboard RAM in the Q950, so I don't know if it would chime or boot the ROM without SIMMs. I'd like to find out though.

 

I too suspected bad RAM, however I know for sure that the RAM test was passing fine, and I never got any related SadMacs. If I can get it booting again, I'll run a RAM test from a floppy, just to cover all my bases.

 

Since I don't have any free time during my work week, PSU is going to be tested next week. I already did some research on where the /PFW line is and such, so I think I'm prepared enough.

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I have not tested every 68K Mac, but of the ones I've tested (and PPC Macs too), none of the models will give a start-up chime/bong if there is no RAM installed (or resident on logic board), except, the IIfx.   The IIfx manages to POST using the 32K of cache on the logic board.

 

Unless the Q950 has onboard cache, I don't think it will bong at start-up without installed memory.

 

 

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you need to pull the PSU apart and check the caps for leakage. 

 

You have to run the PSU under load to find actual faults. unloaded power rails are not an accurate way to test for ripple or regulation issues. 

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I now have the 950 booting happily, and I think I have found the cause... I am so pissed at myself. You may have seen that photo of a little clip on a blue oscillator I was looking at. Well I left that in there during testing! Oh good lord! :scrambled:

 

When I went to test the PSU recently, I removed the unit once more and saw my mistake. After removing the clip, I got the bong, and it booted happily! I looked closely at that clip, and it was quite bent. I think it may have been intermittently shorting that pin to the oscillator housing! I slapped myself for a good minute and tried to think of why I would have left it in there, and I must have figured "It's disconnected, what's the worst that could happen?".

 

PSU voltages look good, and I tested it both under load and disconnected. I will be opening the unit at a later date to check those capacitors.

 

The clip of DOOM!

IMG_0865.thumb.jpg.8273684df4a23d4e97ef5b53e29de60f.jpg

 

PSU Voltages:

IMG_0866.thumb.jpg.daf8e8ffa31190d8a326e0dda2772b32.jpg

 

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That’s the clip for the PowerPump to “inject” a higher clock speed (configurable in the Control Panel) into the stock crystal (via the Output Enable pin on the IC that the red clip attaches to). So you could just reattach both leads and still be OK. Or are you going to go without (33/66 MHz for the 040 and 601)?

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It seems like a design flaw, so I will be adding some insulating tape around that clip before reconnecting everyhing.

 

As an aside, I’ve always wanted an oscilloscope so I can troubleshoot more effectively, so I’m ordering a Looking at getting a Rigol DS1054Z. It’s supposedly a good entry-level scope but has some really soft/mushy detents on the knobs.

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