VOGONS

Repair of 303N1/P60-2087A motherboard

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First post, by sokon

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Hello everyone!
I'm new to the forums, so it's going to be a pleasure to meet you all. 😀
Recently i have gotten my hands on a 303N1 (or P60-2087A, both marks present) motherboard that's missing elements. Looks like someone borrowed some parts for their projects. I hope someone can help me identify their part #s/values in order to replace them and get this thing working.
I have color-coded missing parts on the picture of an intact motherboard as such:

  • blue - elements missing/broken, but identified,
  • yellow - elements unidentified, but presumed to be the same/similar to already identified ones,
  • red - unidentified value, mostly capacitors (ceramic, electrolytic).

Picture is the courtesy of tomaszdko who submitted his to theretroweb.com. My board is exactly the same as his.

The attachment Untitled.png is no longer available

Sokon from Tehnoruum
gemini://tehnoruum.eu

Reply 1 of 3, by rasz_pl

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same deal as DAT18SX REV. C thread
crystals standard 14.31818 MHz 32.768 KHz
transistors any jellybin pnp/npn will do, 2N3906 / 2N3904, BC547 / BC557. The one between ISA slots is most likely NPN for PCSpeaker, otw on the left reset or battery charging.
BC capacitors 100nf
TC capaciors 10uf or maybe 22 47 uf
flat round disk shaped capacitors 10nf
diodes 1N4148
L1 L2 inductors doesnt matter that much, 100nH 1000nH 5000nH any inductance will do, they are there to somewhat filter emi from keyboard cable. Third one near FPU socket no idea what its purpose, might be filtering power for FPU so also meaningless

You can look up similar boards here
https://github.com/Marco-Both/M396F-Replika
https://github.com/skiselev/mb386sx-rc2016

TLDR: all the parts missing, apart from crystals, are of the non critical kind and board should even power up without those (with keybaord error, and maybe after manually inducing reset)

https://github.com/raszpl/sigrok-disk FM/MFM/RLL decoder
https://github.com/raszpl/FIC-486-GAC-2-Cache-Module (AT&T Globalyst)
https://github.com/raszpl/386RC-16 ram board
https://github.com/raszpl/Zenith_ZBIOS Zenith Z-386 MFM-300 ZBIOS disassembly

Reply 2 of 3, by aVd

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Hi, @sokon,
And welcome to vogons forum.

I don't know if this information will help you, but the "unknown 303N1/P60-2087A" 386 motherboard from the picture is exact match to ECS 8517 v.3.3, Gemlight GMB-386SAT and Zida/Tomato 8517 v.3.2 motherboards.

Good luck, with your restoration!

SvarDOS fan :: artificial "intelligence" bots - not a fan at all :: say NO to systemd :: is freeware a lie, when human freedom is a fundamental lie? :: f00ck €u!

Reply 3 of 3, by sokon

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Okay as of now i have managed to transplant two out of three xtals from other, worse condition boards i found, will keep updating on progress

Sokon from Tehnoruum
gemini://tehnoruum.eu

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