Quote:
Originally Posted by bigaudioal
Anyone have a clue as to what might be causing this condition on my Admiral Telebar? Set has had this condition since restore.
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First you need to determine the probable cause to make searching for the failed part or wiring error easier.
Is the set the one you mentioned in this thread:
http://www.videokarma.org/showthread.php?t=261516
If so, there is no bright spot in you test pattern in the first post.
Was this taken prior to recapping?
(There is a complete schematic of that set posted in the thread.)
Also, there seems to be some unwanted ringing on the flyback in your Youtube link in the final post, and that could have been an precursor to what we see now.
If you use that test pattern, or better yet a crosshatch pattern from a color bar generator, you will quickly be able to tell if your problem is from speed modulation of the horizontal sweep or video being contaminated by an as yet undetermined source.
To see if there is an uneven coating on the CRT (unlikely, as your first picture in the above mentioned thread does not show this problem) is to intentionally throw the horizontal out of sync and see if the extra brightness in the center remains. (If it remains, suspect CRT.)
Double check the values including the multiplier on the capacitors across both the horizontal lock coil and horiz linearity coil. It looks like one of these might accidentally be trying to ring at double frequency and the sync circuit is preventing it. (Rare, but it can happen.)
Also, do the electrolytics jumping tests in the power supply test that Electronic M suggests.
Also, the 10MFd across the horiz output cathode.
James.