Defeated by a Commodore 1950 Monitor
Mark J. Blair
nf6x at nf6x.net
Tue Dec 2 23:09:10 CST 2014
Well, I feel pretty dumb now. IC401 is marked "LA7850" on top with no manufacturer logo. Mr. Google suggests it's a Sanyo LA7850 sync chip, and those are available on eBay. So, things are looking better, and I gave up way too soon!
The LA7850 datasheet suggests that IC402 may be an LA7832, LA7833, LA7837 or LA7838. I can't see the chip markings yet, but I should be able to see them once I get the mainboard out to add some test point wires onto the suspicious IC401. It's tucked under the CRT, with the side that I need to probe facing in the least convenient direction, of course. :)
Mark J. Blair, NF6X <nf6x at nf6x.net>
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