sylvania roundie D01

[DaveWM]

thanks DavG

I unplugged the tuner (nice) and cleaned it up, the UHF was stuck, just needed some solvent on the old grease, all good now. The VHF was stiff, turned out to be a tight fit of the plastic channel indicator drum on the brass shaft. I cleaned up, polished up the brass, used some very fine sandpaper to clean up the plastic, got it to a no slop but free to turn fit. Much better now. while I had it out I cleaned up the contacts and lubed the bearing spots.

Before I call it done I am going to go back and double check the HOT and shunt current. The Fly runs hot, but seems to be working fine and the last check of the cathode current was right at 200ma I can get it lower if I reduce the line voltage.

I will also check on some of the other parts that effect the HV regulation. I noticed that a bright scene will result in object being too dark, where as if the lighting is not high in contrast everything is fine. The CRT is weak, perhaps that is the problem, but I still plan the check the two other circuits that effect HV. The 1st is the feedback from the blanker tube, the neg bias at the grid is fed back to the grid of the HOT. This is a design to prevent too high a voltage IF the shunt tube fails. I can see a problem there if for some reason the blanker tube was gassey or for any other reason did not generate the correct neg bias. Next is the shunt tube bias that comes from the video amp. I understand this is to aid in adj HV when there are extended bright scenes. Its a fed from the cathode of the CRT back to the shunt tube thru a 12meg resistor.

I just want to sure that both of these systems are working as designed.