Denial

Hi all, so I've established the other issue (disappearing characters) needs a replacement Character Rom but can anyone help with this issue?

When I got the Vic, the image looked like this...



So I have adjusted the pot to improve image sharpness (only one pot as this is a PAL machine). The trouble is, I have turned it as far as it will go and it still doesn't quite get the image as sharp as it should be. Se below...




So my question is - is this pot trying to compensate for another chip that's just too far gone? If this Vic actually needs 2 replacement roms I'll probably just sell it on for spares.

That's "Dot Crawl" and "ringing", very common issue with the video signal, not a chip issue. Normal on some machines. There are various fixes by modifying the video output circuitry. It looks much worse on a LCD monitor. Turning up the video singal just masks it, and when you get it working stuff will look better with it turned down a bit.

S-Video mod is needed. Disconnect 6561 PIN2 from the mainboard, add a 100uF ceramic capacitor + 360 ohm resistor in series and bring this to the chroma line in a modified S-Video cable.

if your monitor has the tuning "sharp" try to reduce its value