Latest update…
Firstly, happy new year & thanks to everyone who left words of encouragement for me. I’ve done nothing until a couple of days ago when I sprung into action…
IC3, 4, 5, 6 now socketed with new 6821P’s
IC11 also socketed with a new LS138
C28 & C39 and D43 replaced
Continuity tested everything, tidied up everywhere with a fibre pencil, and mopped up with IPA.
Feeling confident I connected up just white power/yellow/aux1/red/red/green leads and powering on I got absolutely nothing… just flo tubes lit. So I unplugged it all and made a brew.
My first thought was scrap it, enough is enough. I do need a 10p solenoid, another machine has an iffy red lead, and a spare PSU and reel driver board will always be good to have etc. But within 10 mins I snapped out of it & started probing about. I discovered a load of pins high on IC9 which had apparently died. Another mpu3 curve ball. Dropped in a replacement for IC9 and connected up… this time reels stepped then spun, well A, B & D did, and C just jammed then alarmed… but I’d never been so happy to see a reel alarm as this surely meant it’s fully booting and no longer stuck in reset!!
I checked the reel driver transistors first and thought it was T49 but replacing it gave no improvement. Probed IC13-IC15 and pins 1 and 3 on reel C’s IC14 were dead. Removed IC14 and fitted a replacement 74LS04 in a socket, and guess what…
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