By golly now that we got more of the schematic to eyeball, there's one more CRT element, the focus electrode or "G3" that hasn't been shunted with the .1 (or .25) cap.
Try clamping it, with the cap going from B+ to "G3" (pin 6). If the bar still remains, Mr. Earlyfilm has an idea i hadn't thought of yet:
Quote:
Originally Posted by earlyfilm
VTS1134,
I see the vertical section attempting to run at 120 cps and it is badly speed modulating the sweep resulting in dual white bands. In other words, the normal 60 cps sawtooth is being speed modulated by a two backwards steps at a frequency of 120 cps.
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Hah. "Speed modulation" of the v sweep waveform itself. That's an idea worth exploring.
IIRC, VTS1134 has a variac. While troubleshooting a vert problem in his vintage Majestic set, the idea was floated of driving the vert. yoke winding directly with the variac. Even though it's a pure sine wave, if it were tried on this set, it would at least reveal whether the bar is sweep derived (ie., 'speed modulated' sweep) vs. a rogue pulse on one of the CRT elements.
02-12-2012, 04:46 PM
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