September 25, 2024
Update for AGC, Sync, Audio rebuild
The printed board that controls AGC, some of the Sync and all of the Audio has been completely rebuilt. I replaced all of the components on this board, not just the capacitors. I found some resistors out of tolerance and a number of cold, poor solder joints throughout. This board was no doubt causing multiple intermittent problems for many years, one of which I experienced earlier in this restoration. There was a horizontal sync problem that mysteriously went away. I decided to do a complete component replacement as opposed to looking for intermittent solder connections and/or faulty components. The CTC5 had numerous issues with AGC and most of that is due to the fact that the engineers thought that it was a good idea to create the 140 VDC power source from the cathode of the audio output tube. VERY BAD design to mix any two circuits that way. I do not know why they did not just add a 20 watt resistor to the existing 285 volt supply which would have been a better design. It would have been a very robust design compared to making the audio output tube do the work of making the 140 volt supply which caused many problems that were difficult to troubleshoot.
Pix 1 Board before restoration.
Pix 2 Board after all components changed.
Next, I go to the High Voltage Regulator and make a mod to allow control of the High Voltage setting.
Cheers, Mike
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