Repairing a 39 year old H/Z-89 Computer

This is my first adventure with repairing a H/Z-89 computer. It proved to be pretty educational for me, and with any luck some folks may learn something too.

Shout out to the SEBHC (Society of Eight-Bit Heathkit Computerists) folks over at https://groups.google.com/forum/#!forum/sebhc - they're an amazing bunch! ... https://www.youtube.com/watch?v=EbAf4jFQcvw