Blizzard PPC possibly faulty - hard crash when using PPC

[Futaura]

After 4 or so years, I finally got my A1200T up and running again, after a mobo issue was fixed. All was fine to begin with, but now whenever I try to run anything that uses the PPC, the screen goes blank and the A1200 power indicator dims.

The card is an unmodified Blizzard PPC 060 + 240MHz 603e with SCSI and BVision. Odd thing is that the 060 works fine, BVision and SCSI too, boots normally and otherwise runs fine, until any attempt is made to use the PPC. A1200 is a 1D4 (ESCOM) board, fully towerised and powered through the main power connector.

Have tried cleaning the A1200 edge connector, SIMM contacts and different PSUs. I suspect the original PC AT PSU had gone bad and maybe a small voltage spike broke the BPPC card, but that's just a guess.

Any ideas?

[Hedeon]

So it worked after the repair and started to show this behaviour later on? Then it sounds very much like a HW problem. On the other hand, this is a BPPC and it already has the ppc started from boot (through ppc.library in its firmware->PUP). So is the problem you have with PUP or WOS software?

The first thought I had was why would it boot correctly if the PPC does not work, doesn't he have WarpDT for the PPC installed :-P

[Futaura]

Yes. Of course, first time I noticed it was when WarpJPEG tried to load my DOpus desktop background . Fortunately, I could boot into Workbench instead where I haven't set a background.

It happens with both PUP and WOS software. With WOS, it even happens with a no startup boot, using the WOS showtasks command.

The BPPC card has been repaired once before many years ago (more usual black screen won't boot issue). This issue is weird though since everything else on the card appears to work fine until the PPC gets used.

I've since tried removing/swapping SIMMs which made no difference. I replaced the clock battery a couple of years ago, so I know that is fine. Disconnecting SCSI doesn't help. Might try it without the BVision next.

[Futaura]

Weirdly, WOS ShowHALInfo sometimes works and displays correct values, but usually it triggers the crash/reboot.

[Futaura]

Ok, so it seems the card may be ok - PPC is working without BVision at least. However, I have to connect a PSU floppy power plug to the A1200 floppy power connector. I always used to do that until recently when my mobo got fixed, but decided not to anymore because everything was working fine without it.

Only mystery is why did it work without the power connector one day for several boots, but next day wouldn't? I guess it could be the 5V rail on the PSU - after all, it hadn't really been used under load for 5 years and the PSU is probably around 20 years old anyway. Not going to risk using that anymore.

Or, could it be the stock fan on the BPPC? Has been replaced a couple of times, but notice it is getting noisy and could be using more current than a new one, if the bearings are going.

[UberFreak]

From experience with a BPPC+BVision combo, if you have voltage lower than 4.85V on the card, strange things start to happen.
In my case feeding power through the floppy connector wasn't enough, I had to connect 5V directly to the BPPC.
Since I did that, the system has been rock stable.

[Futaura]

Is that an 040 or 060 card though? I know the 040 needs more power. I never had any problems with my 060 BPPC in terms of stability.

What certainly is a factor is length and thickness of power cables leading to the motherboard. The shorter and fatter the wires, the better. The cable that I have for my main mobo connection with square connector, I think I bought from Steve Jones many years ago, and it has really chunky wires about 2m long - it had an AT P8 connector on the other end. Worked fine on my old PSU, but with an ATX PSU and a P8 to ATX power converter cable, my A1200 wouldn't boot (power LED stayed dim). The converter had relatively thin gauge wires which no doubt contributed.

Anyway, now I have Ian Stedman's ATX power converter board instead, have trimmed the 2m cable to around 50cm, and have made sure the floppy power cable going to the mobo has relatively thick wires (newer ones tend to be thicker than really old ones) and is the only thing connected to one of the power "tails" from the PSU. Seems to have done the job.