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Originally Posted by Charlie
I spent most of yesterday afternoon going thru the 1950 Raytheon porthole set.
I found a .03 mfd 600 volt cap wired in between the yoke and G2 of the 16AP4. The cap connects at Line 4 (vert) of the yoke and at the top of C104 just before pin 10 of the CRT.
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I looked at 99-14. I think someone added 'vertical retrace blanking' to your set. The .03 cap probably should have a resistor between it and the yoke connection. That's a very high voltage pulse to couple to G2.
The pulses getting through that cap to pin 10 could be 300-600 volts,
probably too much for it.
If I were going to add vert. retrace blanking to this set [I have the 12 inch version] I would feed it from the yoke through a *resistor*, THEN the cap to pin 10, but I'd probably start by finding out what value resistor to wire in by clip-leading a 100K pot in series with the cap and watch to see when the retrace lines go away while I twist the pot, but remember the *HV* pulses! They don't feel so good through your fingers. ;^)
Best luck,
Cliff