BDW Posted January 10, 2016 Share Posted January 10, 2016 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? Quote Link to comment Share on other sites More sharing options...
BDW Posted January 10, 2016 Author Share Posted January 10, 2016 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. 4 Quote Link to comment Share on other sites More sharing options...
+Ksarul Posted January 10, 2016 Share Posted January 10, 2016 Good to know. That actually explains the short period of proper operation after cleaning symptom quite nicely. . .warms up and breaks contact. 1 Quote Link to comment Share on other sites More sharing options...
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