Hello all.
I just picked up a 6-Switch Tele-games that works well, with one exception. The "Game Select" switch causes the console to freeze, or crash, when pressed. I've also observed the game mode increment repeatedly on at least two situations when pressed, but it's hard to replicate. Generally, the CPU just bombs and the image becomes distorted or black. In some games, it appears to continue to run the program but in a glitched state - never actually changing the game mode.
There was another post about the subject where someone had the never-ending mode increment problem, and I think that it was suggested to clean the switches. I've tried that, but it doesn't seem to help.
Looking at the schematics, the switches are pretty simple. Just seems to pull the pin on the RIOT to the common when the switch is closed.
Anyone seen this behavior before? Maybe a bad RIOT or problem between the address or data lines on the 6507? Maybe RAM? I've checked the traces and everything appears to be in good order with no physical damage. Initial observations would tell me that something is writing bad data to the RAM or the RAM is just defective. But games seem to run fine as long as the game select switch is never pressed.
This Tele-games is unusual, in the respect that it appears to physically be a light-sixer shell, made in Sunnyvale, but everything on the PCB appears to make it a heavy-sixer; from the heatsink on the VREG, to the missing channel select switch, to the ribbon cable. I can see no obvious signs that it's ever been serviced or opened previously.
Thanks!