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Old 12-23-2016, 02:31 PM
old_coot88 old_coot88 is offline
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Quote:
Originally Posted by Phil Nelson View Post
Well, the screen image is definitely unstable, although I'm not sure if I would ascribe it only to the vertical. The entire image seems to expand and contract in both dimensions -- horizontal and vertical -- slightly and rapidly. I can also see faint "retrace"-like horizontal lines, both light and dark. It's hard to capture with cellphone video, but these brief clips give an idea what's happening:

http://antiqueradio.org/art/DuMontRA...ngScreen01.mp4

http://antiqueradio.org/art/DuMontRA...ringScreen.mp4

I wonder if instability in the high voltage supply could cause the fluttering in screen size? I tried adjusting the Regulator Control on the power supply chassis, with no improvement. My high voltage meter shows a steady 10KV output, although that meter may not be sensitive enough to show such small, rapid fluctuations.
Is there by chance a faint 'ticking' coming from the CRT socket/base, in step with the fluctuating raster size? Sometimes a pin-to-lug connection is open, creating a tiny spark gap that the CRT beam current is jumping across, resulting in the bloomy raster.
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