Troubles with my TI-99/4a keyboard

[BDW]

Hey all,

 

I've been having some trouble with my TI-99/4a's keyboard. Keys Y through P seem to register as keys 6 through 0, respectively. Enter seems to function as the space bar. I've done some reading, and apparently keys Y-P and Enter are all on the first pin of the keyboard connector, while 6-0 are on pin 2. I've tried cleaning the keyboard cable contacts and the keyboard cable itself has been re-seated, but to no avail. Sometimes the keyboard works as it should for a few seconds, but it immediately goes back.

 

These two keyboard rows feed directly into the inputs of the TMS9901 chip. Should I replace this chip with one from another TI-99/4a, or is it the keyboard itself that needs replacement? Any TI gurus out there that can help?

[BDW]

Just in case someone someday has the same exact problem as I did, here's how I fixed it.

 

I ended up reflowing the pins on the TMS9901 chip. Apparently there was a cold solder joint somewhere, because it started to work again afterwards.

[+Ksarul]

Good to know. That actually explains the short period of proper operation after cleaning symptom quite nicely. . .warms up and breaks contact.