VOGONS


First post, by mt777

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I try to rescue this motherboard.
No mechanical damages, accu leaked very minimal. Traces around accu were good, only elements were affected with green ****.

I desoldered keyboard controller and put socket to replace with other chip. Not helped. Pin of 8042#22 - is not connected anywhere so problem must be somewhere else.
Do you think that replacing F82c206 is good idea?

Reply 1 of 6, by Deunan

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mt777 wrote on 2021-10-04, 00:05:

I desoldered keyboard controller and put socket to replace with other chip. Not helped. Pin of 8042#22 - is not connected anywhere so problem must be somewhere else.
Do you think that replacing F82c206 is good idea?

206 doesn't control A20, it's just a single-chip solution that integrates DMA, interrrupt controller, timers and RTC. If the mobo is cached the A20 will be usually controlled by chipset, internally.
How do you know it's A20 issue? Is BIOS saying that? It could also be cache related problem.

Reply 2 of 6, by mt777

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it boots with strong delay and shows message about a20 gate.
when I swapped with other keyboard controller then boots immediately but stop before calculating memory and endless reset loop.

I can try desolder cache firstly...

Reply 6 of 6, by Eep386

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I had to replace a few TTLs on my Alaris Leopard Rev. C to fix an issue where the cache would randomly not be detected.
While a dying/dead TTL is definitely possible, I'd check for broken traces and lifted pins first. (I also found some lifted pins on the 82C206, which I promptly reflowed, not entirely convinced that was part of the original fault though.)

Life isn't long enough to re-enable every hidden option in every BIOS on every board... 🙁