Diagnosing and repairing a dead Tandy TRS-80 Model 100 portable computer
Channel: Josh Malone
Date: 2020-01-29

In this video, I resurrect a very dead Tandy TRS-80 Model 100 portable computer. I arranged a trade at Tandy Assembly 2019 -- a CoCo2 w/ CoCoVGA, in exchange for some repairs, and this is the last of those. This machine showed almost no signs of life when I tested it at the show, so it definitely needed to go on the bench.

I check the power supply, the address/data bus, and the CPU clock input until I discover the culprit -- a faulty clock crystal. Then, I replace the memory battery, and run some basic tests, including testing the serial port. I also quickly show loading and running the original PCSG Super ROM.

This is the first of what I hope to be a regular repair series. I'm still getting my production feet under me, so please pardon some of the framing and focus issues. Please feel free to ask questions about the process. Also, you can find me on Twitter @48kRAM

Tools used, include:

 * Iron: Hakko 936 at 320 - 350C
 * Tip: T18-K clone
 * Vacuum desoldering gun: ZD-985 at ~330C
 * Scope: Rigol DS1052D
 * Multimeter: Extech EX-330
 * Solder: Chipquik SMDSW .020 63/37
 * Flux: MG Chemical 8341 paste
 * T-shirt:  @MindFlareRetro