Quote:
Originally Posted by Electronic M
A resistor may be needed also adjusting the cap value may help...a good place for decade box engineering.
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I'm thinking the same...
from another thread...
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I often simply hunt for an appropriate waveform somewhere in the vertical oscillator or output stage and couple it through a small value cap to the brightness control of the set. If the video signal is on the CRT cathode and brightness control on the grid, then you want a sawtooth with a rising ramp and a vertical drop. If the video is on the CRT grid and the brightness is on the cathode, then you want a signal with a falling ramp and a vertical rise. Depending on the amplitude of the signal you are grabbing, something in the range of 50 - 1000 pF will usually do it, and typically you need to add about 50-100 K in series with the lead to the cathode or grid, and couple the signal to the cathode or grid end of the resistor.
I've had a few sets where this was not successful. Sometimes the problem is that the sawtooth rise or fall is too fast, and the retrace on the screen isn't done before the blanking pulse ends. The method shown here should solve that problem, since it pulls the blanking pulse off the actual current waveform in the vertical deflection yoke. I'll keep this circuit in mind for future reference!
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and seen in almost every RCA color set, CTC 10-20 , and so on.
https://imgur.com/ZH3uckS
I may try something more like seen here.
IE, VERT OUT-- RESISTOR -- CAP - RESISTOR -- CRT CATHODE --- RESISTOR-- GND