Interesting issue on my Famicom Twin

[theoddtech]

I've got an interesting issue that recently cropped up on my Famicom Twin... it boots up and plays fine on the disk side, but the cartridge side boots to repeating green, black, white bars with a screeching sound. Flip the switch, boots to disk bios (or game if disk is present) no problem. I'd think if this were to happen at all it would be the other way around, but here we are. Any ideas on what to try in terms of repair?

Post Merge: April 08, 2019, 12:17:57 pm
Just got reminded that caps can do weird things, gonna try recapping the whole thing and see if that helps, but still open to hearing other ideas! I have checked the cart connector and there is no debris and no obvious short happening

[Sydsydsyd]

Solid green screen issue is usually related to dirty console socket or cartridge pins. You can use a eraser to clean cartridge pins.
Tell me if that solved your issue 

[theoddtech]

I tried cleaning before posting with no dice. It's not a solid screen, and it gives the appearance of sync not being functional (similiar screen pattern anyway, with jagged lines, and on a CRT they scroll), but have verified that sync is present and at ~15khz

[P]

Most common problems in order, that I think:

1) Dirty, oxidized or worn out pins (cart and/or console)
2) Worn out power adapter
3) Worn out electrolytic capacitors
4) Faulty voltage regulator
5) Other faulty components (fried chips etc)
6) Damaged board

[80sFREAK]

Clean slot with 600 grit sandpaper,if not fixed, you have to reflow slot.

[P]

Ah broken solder connections should maybe be in place 3).

[theoddtech]

Thanks for the suggestions everyone! I ordered a cap kit from console5, and that seemed to do the trick - I really appreciate the help!