Sunday, February 28, 2021

Repairing a Tandy CM-2 RGB Monitor

 Last week I finally received a Tandy 1000A and CM-2 monitor from an eBay seller. Unfortunately, it wasn't packed with the best care and both took some damage. I particular, the monitor was showing only a vertical line across the middle.

With some suggestions from persons wiser on the Tandy Discord, I popped the cover off and looked for disconnected wires and broken traces. And I found the source of the problem, right under the v-hold adjustment knob the PCB had broken.

Hoping the damage could be repaired, I pulled the board and inspected it. 

Not too bad, again with the help of Ken, Paul and Patrick on the Tandy Discord, I had a plan. The three areas in red are where I would mend the board. Paul suggested using solder braid, which made a lot of sense.

So, I applied some super glue and gave it 24 hours to set. Then, I used a tiny screw driver to scratch down to the copper.

 After cleaning with IPA, I soldered the solder wick to the board. I also removed the old solder from the joints that were on top of the crack and resoldered them as well for good measure.

Back into the monitor for a test and looking good! I had to adjust the pots on the flyback transformer to reduce the brightness, but otherwise it's working fine now.

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