Westinghouse 22 inch color restoration - Page 4 - Videokarma.org TV - Video

reeferman · #46 10-15-2009, 05:58 PM

And to think I was impressed when the Sears Tower opened!

oldtvman · #47 10-17-2009, 05:10 PM

Now we know that with few exceptions the early color sets did a fantastic job.

Now if I could just rent a time machine to go back and buy a few and bring them home.

Steve K · #48 11-08-2009, 07:00 PM

Here is finally an update on the Westinghouse. I fixed the video smear problem and did a basic IF alignment (after I had to buy a new scope).

I might have discovered the major problem with these sets. As seen in my earlier posts, the color and convergence is really very good. However, a few days ago I suddenly lost purity. The only way to get a good pure red, blue, or green screen was to pull the yoke all the way back, just the opposite of normal. As I was messing around with it the purity popped back in. After discussing this issue with John Folsom we decided that this may be due to the shadow mask distorting. Darn. If anyone knows what else could cause this please let me know. I have tested eveything else I could think of.

I have added some more pictures. some of which show it in the cabinet. The purity is bad now. I will add a few more pictures when it flips back.

Steve

Charlie · #49 11-08-2009, 07:09 PM

Shadow mask distorting?? Can you go into a little more detail Steve?

Steve K · #50 11-08-2009, 07:29 PM

John refered to it as "oilcanning". I'm not sure if that is just what he calls it or not but it means that the mask can pop in and out at the center.

Steve

old_tv_nut · #51 11-08-2009, 07:33 PM

What video had you been running when the purity "popped" and what did you then run until it popped back? If it is the shadow mask, it seems like it must be some really sudden movement due to thermal expansion and "oil-canning." This is the first I have heard of a tube popping out of purity suddenly. Usually overheating causes "doming", a gradual loss of purity in a bright area like the white patch on composite color bars.

Steve K · #52 11-08-2009, 07:58 PM

Wayne:

I had the cross-hatch pattern on from the NTSC generator. I really want it to be something else but I don't know what it could be. When I first got it working I adjusted purity the normal was, yoke back, center red, etc. Thenk when it went bad I could only get a red screen with the yoke all the way back. I get good color in the middle 12 inches or so of the screen but off colors all around. I just tried it a few minutes ago and it came up good for about 5 minutes then went ouot.

Steve

Charlie · #53 11-08-2009, 07:59 PM

Wow... that would be one hell of a tube defect! Seems if it was indeed due to heat, seems like the set would have to cool back down before the mask would pop back into the original position. Was this something that showed up only after putting everything back into the cabinet? If it happens more often while in the cabinet and less often or none at all while out of the cabinet, then it would certainly be something heat related.

old_tv_nut · #54 11-08-2009, 08:07 PM

Quote:

Originally Posted by Steve K

Wayne:

I had the cross-hatch pattern on from the NTSC generator. I really want it to be something else but I don't know what it could be. When I first got it working I adjusted purity the normal was, yoke back, center red, etc. Thenk when it went bad I could only get a red screen with the yoke all the way back. I get good color in the middle 12 inches or so of the screen but off colors all around. I just tried it a few minutes ago and it came up good for about 5 minutes then went ouot.

Steve

In # 17 you said it has a field neutralizing coil - maybe that's the problem - either losing all current or something shorting and putting in too much

ceebee23 · #55 11-08-2009, 08:54 PM

I know we have all said it..but WOW even with the "oil can" just seeing this set ALIVE is about as close the the holy grail as you can get!

yagosaga · #56 11-09-2009, 02:46 AM

Hi Steve,

the purity on the photos still looks good. There are some minor tinted spots in the corners, but IMHO they are acceptable with such a special set.

I had shadow mask troubles with the early A63-11X. One tube had a bended mask, and it was impossible to get a good purity. If the left part of the screen was clean, the right part of the screen had changed colors and so on.

The GE Porta-color crackles inside the CRT when the shadow mask is warming up.

IMHO your observed fault depends on the mounting brackets of the shadow mask inside the CRT. The CRT was not used for decades. With a rigid restraint of the shadow mask, it is not possible to get a good purity all the time. Mounting brackets and shadow mask need some compliance, otherwise the shadow mask will be tilted with warming up. IMHO the interaction of the mask and the mounting brackets is not well balanced. This could be due to the long time of quiet. I suggest tests with further operating of the tube with low beam current for 15 minutes, with normal beam current for ten minutes, and if you do not get significant results, with high current for five minutes. What are the results? Perhaps these data might more isolate the problems.

This is the procedure which I run for CRTs with bad purity.

Question to the others: is this a suitable way of testing or is there a chance of an irreparable damage of the CRT?

Kind regards,
Eckhard

old_tv_nut · #57 11-09-2009, 10:09 AM

I am hoping it's the field neutralizing current. Was the crosshatch white lines on black background? That should not cause enough heating to make the mask change.

kx250rider · #58 11-09-2009, 10:21 AM

I agree on the field neutralizing circuit. If it's the shadow mask, then temperature should affect it. Have you tried putting a big fan behind the set to cool it down, and see if the mask pops back into shape? I've seen a 40" Mitsubishi CRT do that, although it had been clobbered (loosened the mask from it's mounts, or something). as the set warmed up, you'd hear "Boi-oi-oi-oingggg", and the purity went to heck. You could also give it the fist in front, and it would look like a stone thrown in still water with color ripples.

That Westinghouse got slammed around in a rough ride in my TV room in '94, and nearly fell off where it was sitting. I found it wedged between the wall and a console set, and it had been shaken up pretty badly. A couple of the knobs that fell off, got under a file cabinet and were crushed. If the mask is dislodged, blame the Northridge Quake

.

Did (present owner) give you the correct volume knob? I don't remember seeing it on the set last time I was at his place...

Charles

roundscreen · #59 11-09-2009, 07:55 PM

I have seen set's that the purity will go out when the contrast is set to high or on a bright white screen at normal settings.
Someone told me the electrons where hitting the shadow mask with a lot of force and it was moving the mask enough to mess up the purity.
Double check the high voltage and the crt screen settings. Then try turning down the contrast to a point where you can just see the red and see if the problem goes away.
Still that is one cool set you have and I hope you find the problem.
Ed

Steve K · #60 11-09-2009, 08:03 PM

Wayne:

I bypass the neutralization coil and it has no effect.

Ed:

I was just playing with it and if I turn the contrast all the way down it is OK (but not perfect). Just increasing it a little throws off purity. I still have the problem with yoke position however. My screen settings should be OK. I will check HV again but it is not easy with the chassis sitting flat on the bench. The odd thing is is that I didn't have these problems originally and I don't know what I could have done to mess it up. What a piece of junk ;-)

Steve