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#1
12-09-2011, 07:26 PM
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rca roundie
finally got my ctc 15 together.its been working great for the last 3 months.today it develpoped a problem.the bottom 1/3 of the screen is slightly out of focus.no hum or weaving.the top 2/3 is clear and looks good.the bottom part is slightly lighter and a little out of focus.any ideas?as i said before,i am a novice
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#2
12-09-2011, 07:31 PM
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glad you finally got it working!crt checked out well.you sure there isnt a weave or slight hum?
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#4
12-10-2011, 12:05 PM
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That's not something I recognize by description... The only thing I can think of, is some sort of a blanking problem, and that's a wild guess. Any way to get a picture of the screen? The focus, as far as I can think of, would be impossible to have good on one part and bad on another, since it's a linear 5K volts and I don't see any way it could cycle with the scanning.
Charles
__________________
Collecting & restoring TVs in Los Angeles since age 10
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#5
12-10-2011, 12:14 PM
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could a weak 130pf cap on the focus coil be a problem, the one that connect to the + of the focus rectifer (or focus tube cathode) and the 66 meg resistor.
Last edited by DaveWM; 12-10-2011 at 12:17 PM.
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#6
12-10-2011, 01:20 PM
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Could the OP be noticing convergence issues? I've had customers tell me that part of the screen needed focusing... and it was convergence. Just a thought...
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#8
12-10-2011, 07:29 PM
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Im thinking of a peaking coil. I had a time with one on a CTC-24 that had a lighter shaded band across the screen more than once.
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#10
12-10-2011, 08:28 PM
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vertical is working good.full picture with the right proportions.watching it today and the bottom 1/3 id lighter that the rest.slightly out of focus because of brightness issue.looks very good just this problem i wiggled tubes around in their sockets,no luck.tapped on the circuit board hoping to find a break.none found.rotated focus control and can get bottom very sharp but the rest goes soft.picture tube is a rca rebuild that was checked and is excellent.i really like the picture just this bothers me.i will try to swap out video and blanker tubes to see if it changes.after that i am at a loss
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#11
12-10-2011, 08:54 PM
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The focus physically changes? Wow. Could it be the rebuilt tube? I wonder if something has shifted in the tube.
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#12
12-11-2011, 12:06 PM
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i saw this set today.it does have a portion of the screen lighter at the bottom.since its brighter,i looks a little soft.i have never seen this problem before.we proded with a wooden dowel but no effect.it could be a video issue.crt is very good and the color is outstanding.lit looks great while watching a movie and is only noticeable whenthere is writing about the bottom.all circuits are working right so i am a little stumped.focus is working and center looks fine.the brightness at the bottom third is the problem.not a focus problem but brightness.it almost looks like a hum bar but doesnt move or bend video.
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#14
12-11-2011, 04:12 PM
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no vertical foldover whatsoever.this is like a hum bar that has stopped.it doesnt travel,just a band of video that is brighter across the bottom third of screen.also there is a pop when the high voltage hits it.looks like a rubber grommet not on chassis ground.i will bring one over for him.hope he can post pics.i have a sams and will try to help him out.very good looking set!
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#15
12-11-2011, 07:36 PM
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If you roll the vert does the bright patch roll with it? If so this could be a symptom of a vert issue.
__________________
Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4
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