Major title 2

RMRepair

Newbie
Credits
67CR
Major title 2 sold to me as dead.

Sure enough no sign of life on the screen, however these take a while to fully boot up after the self check, so I waited 20 seconds, sure enough I heard it boot up. No schematics exist as far as I know, so whipped out the probe. Randomly probing what I thought was the video circuit I came across 2 x 74ls273s (ic9,ic10)with the clear signals(pin1)stuck low.
20230324_090441.jpgTraced this back to a 74ls74(ic53)pin 8(output) This was tied to pin 9(output) on the underside of the board, with pin 9 on the chip cut off which is correct. 20230324_090707.jpg Both pins where stuck low, now pin 8 is connected to pin 7 with a capacitor sitting on top of the chip, slightly damaged. Pulled of the cap, dead short, new cap on and the screen came to life.20230324_090009.jpg
20230324_090353.jpg
 
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