I'll probably make a thread about this at a later date, but I have a Compaq Deskpro 4/25is. A 25mhz i486 system that was already old when I got it 15+ years ago. Taught myself programming on the thing. Gave me a real appreciation for code optimization!
Anyway; I pulled it out of the basement the other day and tried to boot it up.
Carefully
I opened it up, and checked for corrosion & sus capacitors. Then pulled the PSU out and fired that up separately with a dummy load. No sparks or pops.
Reassemble everything, found an old vga monitor, cut pin 9 out, found a ps2 keyboard, and fired it u...
InstantPOPflash.
Well ----.
<MOD EDIT: LANGUAGE>
One of the caps on the riser board had blown up.
Removing the riser, everything else
seems to
work†, well,
not-explode, but it doesn't POST.
† hdd spin up, power LED, LED on Main-board, CPU warms.
Maybe someone else here is a vintage enthusiast or involved with board repair and can guide me towards identifying/fixing the problem.
My problem is that several things could be wrong, and I have neither the electrical experience nor the documentation to figure out which.
In order of suspected likelihood:
- The PSU is not supplying the correct voltages to the main-board/one of the power rails is on the fritz.
- The blowout fried something else that isn't visually obvious. (The CPU does warm up though so hopefully not that!)
- Something I don't know enough about to even consider.
- The riser board is required to POST.
- It is posting, but all my HIDs are too new or not being recognized or powered properly. I'd expect a beep from the speaker or a LED on the keyboard at least though. And I'm not getting even that.
- The BIOS or CMOS is corrupt
- There are other components on the mainboard that have independently died in the last 15 years, besides the popped cap.
The worst is that I can't find manuals or diagrams for anything. The ones at "hp.manualscollection" are not actually for the /i series despite their claims to the contrary.
And the beautiful specs sheet at
https://www.1000bit.it/ad/bro/compaq/compaqdeskpro-ispecs.pdf while correct, is not helpful for board repair.
Thoughts, advice, or commiserations welcome.
Or '
F's for my lovely vintage i486. I really hope it's not dead for good though.