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Old 11-12-2025, 04:04 PM
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Bob Galanter
 
Join Date: Sep 2005
Location: Whitefish Bay, Wi (Milwaukee)
Posts: 1,069
Found the problem

Thanks to all who made suggestions

I took Kevin Kuehn's suggestion and measured the grid of the Horiz output tube 6BG6. It had a nice saw-tooth waveform, but when I calculated the pulse width on my scope it appeared that it was running about 1/2 speed at about 7800HZ.

From there I figured that something had to be amiss in the horizontal oscillator section. So I started testing values. I found a bad mica cap across the H freq coil that was shorted, and I replaced it. That did not fix the problem so I kept testing. Then I found a 270K (R87 on the hallicrafter schematic) that had drifted to 780K. I replaced it and the oscilator speed just about doubled. After tweaking the H-Oscilator freq coil, the picture came into sync and I had a perfect full picture.

Again thanks to all that contributed. So many knowledgeable techs that know a lot more than I do.

Bob Galanter
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