Commodore PC 10-III repair \ VOGONS

Commodore PC 10-III repair

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First post, by Kekkula

Posted on 2025-09-06, 11:26

Kekkula Offline

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Hi.
I recently got this machine. Of course there was leaky varta still installed. I cleaned the board with vinegar and ipa, and the damage doesn't look bad... but there was damage of course.
There is one completely missing and two damaged pins in main chipset socket. Pin 81 missing, 80 and 79 damaged. I think they are irq 5,6 and 7, so the machine should still work without them?
Does anyone know good ebay seller selling that socket, ordering one socket from mouser or similar place will cost arm and leg.
Other than that there is just, capacitors resistors and few 74 series chips and one oki chip that I don't know what it is, maybe damaged.
Psu also has +5v line shorted.

Reply 1 of 4, by dominusprog

Posted on 2025-09-06, 14:39

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For the short, check all the tantalum capacitors first.

https://www.ebay.com/itm/404966684945?_skw=84 … ABk9SR7SbtfejZg

https://theretroweb.com/chips/3068#docs

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Reply 2 of 4, by Kekkula

Posted on 2025-09-06, 16:19

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Found the short from the power supply. One of the capacitors 10v, 1000uf was shorted and other two just bad.
Now the problem is I only got two 10v 1000uf capacitors, but I have 16v 1500uf and 25v 1000uf which would be better?

Reply 3 of 4, by Jo22

Posted on 2025-09-06, 16:43

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Kekkula wrote on 2025-09-06, 16:19:

Found the short from the power supply. One of the capacitors 10v, 1000uf was shorted and other two just bad.
Now the problem is I only got two 10v 1000uf capacitors, but I have 16v 1500uf and 25v 1000uf which would be better?

For classic power supplies? The 25v, 1000 µF types, I think.

Personally, I don’t like 6v or 16v caps. They're too close to standard voltages.
Which means they age so quickly because they're working at their tolerance all time.
(5v TTL vs 6v cap, 12V PSU line vs 16v cap)..

PS: Before the topic of ESR comes up:
Traditional transformer PSUs are okay with oversized capacitors and a high Q factor.
It's mainly 21th century tech which likes low ESR.

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In what to one race is no time at all, another race can rise and fall..." - The Minstrel

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Reply 4 of 4, by Kekkula

Posted on 2025-09-06, 17:45

Kekkula Offline

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Thanks... I already replaced 10v ->25v there is two more 25v 1000uf caps on board I will replace them too. Then I have to see what smaller caps do I have.

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