The Synertek SYM-1 that I've used for several years suddenly stopped working. I think it broke when just sitting a bit ago, because a couple months ago it was working correctly, but no longer.

The symptoms:

Upon power on, the SYM-1 should beep once, then wait for the user to either press the hex keypad CR button, or send a Q over the terminal. This will determine that session's default output.

Upon pressing a button, the text SY 1.0 or SY 1.1 (rom version) should be displayed on the LED display or the terminal, respective of what you see.

However, right now, when I power on the sym-1, I get a beep, the LED display shows up, and the CR key doesn't work. The Reset on the hex keypad still works, but no other keys do except for some strange behavior by the USR buttons. No beep is heard from the CR button, but I should hear one every time it is pressed.

Do any of you more experienced people have pointers on where to look/debug?

It is almost always mechanical contact issues. Toggle every switches many times; check and reseat the power and connectors; and remove socketed IC and plug them back in. Visually inspect board for conductive particles; check power voltage level.
Bill

I'll try that again. I'll probe out power lines and such, I'll try and see what the reset line says and things like that. It is an old board!