I repaired this little Trinitron this weekend. KV-1204 from 1976. A friend of mine rescued this from the recycling, and gave it to me because it was dead. I replaced a few bad capacitors on the deflection board. The picture tube is really strong, which is unusual on these old Trinitrons.

Got it all working and reassembled. There was a cracked trace causing an address line to be connected to only two of the RAM chips, and nothing else. This was acting like an antenna and picking up noise.

Still missing a couple keytops (1, Z, and left Shift), but I found a couple I could substitute.

I can honestly say I've never seen a 2102 RAM chip behave like this before.