Okay, it's not like I don't have a million other things to do. Ah, the joys
of procrastination..
Anyway, I found the TR-77 User Manual. I'd assume that there's more
similarities than differences between the two machines but others could
verify that better than I could. I have a TR-55 and never was able to find a
schematic for that (if anybody has one let me know) but all these early beat
machines seem pretty similar.
Here's the link to the Service Manual:
http://rvgm.l4rge.com/Here's more info on modding the TR-77
http://www.burnkit2600.com/tr-77/Hope that helps a bit.
David (posting too much this morning and ripping off Mr. Servo by adding
comments in parenthesis between my first and last name) Luft.