Heavy oxidation on cartridge connector pins preventing reliable reads.
3 repair logs
Nintendo — AV Famicom
This Nintendo AV Famicom (HVC-101) arrived with a gray screen and a catastrophically oxidised cartridge slot. A good clean fixed the boot issue; a full recap and 7805 voltage regulator replacement took care of the rest.
Nintendo — Game Boy Player
The first time I've actually encountered genuinely leaking capacitors in Nintendo Game Boy Player (DOL-017) units. These were memorable for that alone.
Virtua Racing Deluxe back in action after a recap and a clean. Whether the cap was actually the cause or the IPA did the real work is unclear, but it works now.