CRT leading and trailling blue - Videokarma.org TV - Video

DaveWM · #1 10-14-2010, 09:28 AM

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

Help....

DaveWM · #2 10-14-2010, 09:29 AM

I will post a pic later in the day

DaveWM · #3 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 · #4 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 · #5 10-14-2010, 11:08 PM

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

DaveWM · #6 10-15-2010, 08:47 PM

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 · #7 10-15-2010, 08:56 PM

here is a better example

miniman82 · #8 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 · #9 10-16-2010, 05:21 PM

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

jpdylon · #10 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 · #11 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 · #12 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 · #13 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* · #14 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 · #15 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