QUICK REPAIR: “Analitik” VMC001 monocrome monitor (Аналитик ВМЧ001)

One of the many tasks in the museum is to have the appropriate era-correct monitor for our Pravetz 82. We managed to acquire one or two throughout the years, but they had missing transformers and CRT yokes that were stolen from scrapers for their expensive copper. Well, a recent donation to the museum was another monitor from the same model, that was used in every Pravetz 82 configuration back in the day. To my surprise this time everything was intact, only a single fuse was missing. Maybe this time the scrapers missed this monitor.

The new monitor

At first glance installing a new 0.3A fuse didn`t fixed the issue, only the power LED was on and the high voltage flyback noise can be heard coming out from the inside of the monitor. Taking the lid off revealed lots of dust, which needed cleaning and that the CRT had no heating.

The back side of the monitor

The missing 0.3A fuse

There were two more 0.6 A fuses located on the analog board and one of them was burned. Replacing it also did not fix the problem with the missing heating.

The fuses on the analog board

During closer visual inspection there was noting obviously problematic on the board and then BINGO, the workable light shinning at the back of the CRT revealed that it probably lost its vacuum.

The damaged CRT

The good news is that we have a parts donor in storage and I can only swap the CRT`s and replace the missing yoke on the spare tube.

The parts donor
The front panel removed
The old CRT is removed
The old and new CRT`s

Swapping CRT`s made some progress, the heating was now working but the monitor had noting on the video input.

The working heating

I didn`t wanted to go through the trouble of diagnosing the analog board so I just swapped in the board from the parts donor and just hoped that it works. Well, it did work only some picture corrections needed to be made from the trimer pots located on the analog board. Now we have a perfectly working monitor for one of our Pravetz 82 computers.  

The front panel assembled and monitor working
Everything assembled

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