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Should I Attempt to Fix Vertical Collapse on a Tandy Color Monitor CM-5?

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sethorama

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Dec 28, 2023
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Hi everyone, first time posting. I have a Tandy CM-5 I got with a DTK data 1000. It's the only CGA monitor in my collection (and so it's the only monitor I have for the Data 1000). The monitor worked for about 30 seconds when I first powered it on before shooting sparks everywhere. It was a direct short between a resistor and a diode on the board. Replaced the damaged resistor and diode and when I powered it on again, it had vertical collapse. Is it worth trying to troubleshoot and fix it, or should I just move on and try and find another monitor for the DTK? Thanks all.
 
The CM-5 dot pitch is terrible. I think it's around twice that of the IBM 5153. So even when the monitor is working correctly, it's pretty hard on the eyes. I know because I have one.. :cautious:

If you want a monitor to use on a regular basis, I would look for something better. That said, nobody is making new CRTs, so if the CM-5 can be repaired, don't throw it out either.
 
I can't find a schematic but are you sure you didn't bump a service switch inside ? Some CRT's have a slide switch on the board to drop it to a line
to do RGB level settings. Those switches can get dirty contacts too. Although I see both CM-4 and CM-8 service switch keeps a full raster so maybe not.

Larry G
 
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Since there was a short, I would look for a fusible resistor that could have gone open. You can start by confirming that the vertical IC is getting power. With no schematic, you can use the datasheet for the IC to find out which pin is for Vcc.
 
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