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Update
Just wanted to give an update to my troubleshooting quest for this set. After digesting the responses on this thread, I did take a good look at the CRT neck board - I cleaned the sparkgap unit with alcohol as suggested and checked the coils on this board along with checking for cold solder joints - everything checked out OK. I then decided to take a look at the screen control - this is separate from the flyback. I discovered that if I just touch the control, it caused a big fluctuation in the screen - bringing on the bright screen with retrace lines. Of course I figured it was dirty, so the most I could do was to rotate the control since it would have to be removed to clean - rotating didn't help. By shear luck (I believe), I was able to find a brand new in box focus/screen control unit for this set from Moyer Electronics in Pennsylvania for around $30 with shipping. I installed the new control this past Saturday and have had no reoccurrence of the bright screen with re-trace lines. I am convinced that there was something wrong with the old control as it was very sensitive to touch causing major changed in brightness. This control is more complex than just two potentiometers - it is a divider network with resistors integrated into a cermet board.
So far, no bright flashes. However, I still get the occasional red flicker - so something else is still up in this set. I dialed in the driver and bias controls again - along with the screen controls per RCA specs and also using a color meter, calibration software and DVD screen patterns - so I have excellent greyscale and color. The picture is excellent - except for the occasional reddish flicker - it is almost like an increase in the flesh tone - not a full on saturation. Maybe a leaky transistor or cap. I didn't change the video buffer transistor or the power regulator transistor as mentioned in responses on this thread - I did source them and may change them next. The only other thing I did change was the main filter capacitor. I didn't have to pull the chassis to change the filter cap or the focus/screen control.
I have attached pics of the chassis and new control. Thanks for the responses, it helped and any other input on this reddish flicker is appreciated!
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