@commodorelad.uk could I pick your brains on a breadbin fault - 250407 board, powering up from cold produces normal border and screen colours, but lots of @ and graphic characters. Works fine when it's been powered on for a bit then reset. Thinking PLA? - ThreadSky

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balford.bsky.social • 74 days ago

@commodorelad.uk could I pick your brains on a breadbin fault - 250407 board, powering up from cold produces normal border and screen colours, but lots of @ and graphic characters. Works fine when it's been powered on for a bit then reset. Thinking PLA?

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commodorelad.uk•74 days ago

Could be PLA or ram multiplexors. Any MOS logic on the board? A pic of the board would help.. Also pic of the fault.. 👍

balford.bsky.social•74 days ago

Didn’t crack it open tonight as it was getting late, and the machine was stable warm unfortunately. No MOS logic that I can remember but it’s been a while since it was open. Will try tomorrow!

commodorelad.uk•74 days ago

Cool, get a pic of the fault and the board and I'll help all I can bud. 👍

balford.bsky.social•74 days ago

Here’s the board, typically it’s starting up fine this morning. Ray Carlsen’s guide suggests a bad U27 as that screen is close to it, so if it reappears I’ll throw in a new LS08 there first. Cheers dude 🙂

commodorelad.uk•74 days ago

I'll refresh my memory as to what that does, I think it's address decoding for the VIC. Unusual for it to fail cold tho. Also definitely worth checking the VIC socket as the ones Commodore fitted originally were and still are crap. 👍

balford.bsky.social•74 days ago

Easy for me to whip that socket out and replace as a first step. Cheers!

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