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Nanochess, You mean pin 36 on 9928? the Y signal? The screen does go from snow to black. Correct me if I'm wrong, but I thought the 9928 sent the y, r-y, b-y signal to the LM1889 to be encoded to be composite? Nebulon, Those are the exact manuals, I've been using... I'm on sheet 5, and sheet 9, both deal with video problems. On sheet 9, U9:34 low? = Mine is high... -> U7:13 high? Yes mine is -> = "Check U7/U1" That to me says change processor or U7, U7 runs the reset switch, and that seems to work properly. However on sheet 5, U9:40 good? yes, I have clock signal -> U9:36 good? -> No picture, so I think, no -> Change U9 (VDP) Soooo brings me back to is it bad processor or VDP? Thanks for your guy's input...

Hello, I'm new here, I'm trying to fix my coleco. Maybe someone can help? I have no video, just a black screen. No coleco title screen, with insert cart. I started with all the usual stuff, power switch etc. With expansion mod 1 plugged in I do get video, and sound. I can assume the RF board is fine? I've followed the flow charts in the repair manual. I have both the 3m and 10mhtz clock signals. The sound is off, no lingering tone. I suspect the processor is fine and the VDP is shot? How does one verify this? To me the rest is all TTL logic, I have more than one board, so short of brute force and ignorance, socketing the bios, vdp and processor, and swapping until it works? hints, tips? Anyone? Thanks.