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-   -   CRT leading and trailling blue (http://www.videokarma.org/showthread.php?t=249064)

DaveWM 10-14-2010 09:28 AM

CRT leading and trailling blue
 
on dark scenes when there is bright white text I get a leading and trailing bluish tinge across the screen.

Help....

DaveWM 10-14-2010 09:29 AM

I will post a pic later in the day

DaveWM 10-14-2010 02:51 PM

adj the blue cathode drive pot does not seem to have any effect on the pic, while the green pot does. don't know if that is related but I will check the cathode voltages later and see.

miniman82 10-14-2010 03:20 PM

Usually the cathodes have video (luma) on them, and the grids carry color (chroma). If anything, you need to adjust the grids.

jpdylon 10-14-2010 11:08 PM

Turn the color off. Does the problem still show up then?

DaveWM 10-15-2010 08:47 PM

1 Attachment(s)
with color turned down I do NOT get the trailing effect.

I have two Zeniths the 20x and the 20y both chassis exhibit the effect.

DaveWM 10-15-2010 08:56 PM

1 Attachment(s)
here is a better example

miniman82 10-15-2010 10:57 PM

Looks like either tuner or chroma related ghosting, or the blue lat magnet (if it has one) is out of position.

rcaman 10-16-2010 05:21 PM

it does not look like the crt is at fault . steve

jpdylon 10-17-2010 11:18 AM

First try adjusting the fine tuning to see if blue shifts or disappears. You might have a slight video smear or color misalignment. Does this set have all the plugin boards? Have you cleaned the contacts and resoldered the connectors on the boards?

DaveWM 10-17-2010 04:06 PM

if I detune enough to lose color the smear goes away, other than that I can't fine tune it out.

No plug in boards, all hand wired.

freakaftr8 10-18-2010 03:54 PM

Almost every vintage set besides my CTC-40 does that as well, RCA and Zenith. Not Sure where the problem lies either

old_tv_nut 10-18-2010 10:02 PM

Hmmm.. wonder what is common about the sets that show this. Do they all have surface-wave IF (SWIF) filters, for example? (Trying to guess what could cause such a long trailing smear in the chroma). If it was in luma, I would be looking at grounds and components around the delay line.

zenithfan1 10-19-2010 09:13 AM

Have you tried turning the blue gun off to what just the red and green do? Then, turn them off to see if it is blurry and trailing only when the blue gun is on. I've seen one gun not focus when the others do, it's usually when one is weak or the tube is shorted. Just a thought....

Geoff Bourquin 10-19-2010 10:47 PM

Looks like poor frequency response in the blue channel to me. Kinda like when you hang a meter on the collector of a video output transistor and it smears


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