I have a white PCE that is showing horizontal flowing interference lines. The system is unmodded and came to me in pretty bad, smelly shape. It originally ran fine when I first tested it (played about an hour of Gunhed), but after I discovered the controller port on the PC Engine was extremely sticky I cleaned it out with a tooth brush and Isopropyl 99%. After doing that, the controller port is fine but these interference lines suddenly appeared. I opened up the console thinking I broke something with my controller port cleaning but the board looks fine.
I cleaned the PCB carefuly with ISO 99% and Q-tips and got quite a bit of brown residue but no obvious signs of damage, no visibly bad caps, etc. The only thing I haven't done is open up the IFU itself.
I've tried a few different games and cables but they all have this interference pattern. Sadly I lack the tools to test if its the IFU or the PCE as I don't have any video or power cables for the PCE itself. Screen is my dedicated gaming CRT TV that doesn't have issues with other composite consoles. No other connectors, splitters, or anything else is between the console and the TV composite input.
Below is the interference I'm seeing:
https://www.youtube.com/watch?v=LqWof-98dDIThanks everyone!