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  #1  
Old 07-31-2017, 09:27 PM
FrankieKat FrankieKat is offline
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Westinghouse H886K21

Hey everyone,

I've come into a 1955 Westinghouse H886K21 which is my first tube TV set. I've done restoration and repair of tube radios and HiFi, but no TVs. Having watched many hours of YouTubers' TV restoration videos I felt foolhardy enough take this on.

I found it with a brightener (which I removed) and roughly 2 out of 3 tubes tested weak and a few with minor shorts. Before pulling the chassis I've first tried replacing tubes to see if I could at least get a baseline. Came up right away with full horizontal, some vertical but no visible image and after replacing a few tubes and working controls free, I was able to get sound, but still no image. There's a low level of constant static in the background of the audio, but otherwise it's full and has good volume so we know front end is functioning. I've also replaced the sync amp, the sync separator, AGC keying, vertical mult, vertical output and horizontal AFC tubes, which has yielded little change.

Here's a video of where it's at:

https://youtu.be/vGhXHNI5qdE

In the video, I'm first adjusting the brightness, then the vertical hold then the horizontal hold (clearly the control needs a good cleaning). Adjusting the rear sync, height, width, linearity, AGC controls affects the height (though never goes below the top half of the screen vertically) but still no solid picture.

As I haven't yet even pulled the chassis I'm obviously not expecting perfection as it's likely on a good amount of original components. I'm more inclined to want to troubleshoot to learn as much as I can, instead of just doing a wholesale/shotgun replacement of caps, etc.

So I guess I'm looking for some advice for where I might start, and next obvious steps to try to sort out my little vertical problem, first?

Thanks!

FK
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Old 08-01-2017, 11:40 AM
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I hate to be the bearer of bad news, but with a set of that vintage, a shotgunning of the original paper caps is strictly necessary. A set in that state is essentially impossible to troubleshoot as you suggest. There's no video, weak sound, insufficient vertical sweep, horrid hum (though it might be 6BN6 buzz; Westinghouse and Zenith were fond of the 6BN6 in that era). And that's just what we can see that's wrong with the set. You could be running at extremely high horizontal output cathode current thus putting your flyback at risk, etc.

Plan on replacing all the paper caps and electrolytics, but you can do what I do (as suggested by Phil Nelson): replace a handful of paper caps, say six or seven, then plug the set in and make sure you haven't made anything worse.

Start recapping in the sweep sections and power supply first to avoid nuking an unobtainable part.
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Old 08-01-2017, 02:47 PM
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...and if you need the Sams Photofact, it's Set 294, folder 11. I have an original, yours for postage. PM me if interested.
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Old 08-02-2017, 03:17 PM
FrankieKat FrankieKat is offline
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Quote:
Originally Posted by benman94 View Post
I hate to be the bearer of bad news, but with a set of that vintage, a shotgunning of the original paper caps is strictly necessary. A set in that state is essentially impossible to troubleshoot as you suggest. There's no video, weak sound, insufficient vertical sweep, horrid hum (though it might be 6BN6 buzz; Westinghouse and Zenith were fond of the 6BN6 in that era). And that's just what we can see that's wrong with the set. You could be running at extremely high horizontal output cathode current thus putting your flyback at risk, etc.

Plan on replacing all the paper caps and electrolytics, but you can do what I do (as suggested by Phil Nelson): replace a handful of paper caps, say six or seven, then plug the set in and make sure you haven't made anything worse.

Start recapping in the sweep sections and power supply first to avoid nuking an unobtainable part.
Well, shucks. Was hoping it'd be like one of those videos where replacing a few tubes and it plays "fairly well". Beginner's luck I suppose!

It's possible the sound issues you mentioned could be caused by the cheap DTV box I was using for that, so if that persists after doing recap I'll try other sources and see.

I've ordered a full set of caps and agree with your technique of recapping in small batches to make it easier to spot and roll back mistakes. The good thing is that this cabinet has a lot of space to work and seems very simple to get the chassis in and out so hopefully this will be a good learning TV!

Thanks for the advice!

FK
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Old 08-18-2017, 02:18 PM
FrankieKat FrankieKat is offline
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Update -- finished replacing paper and electrolytic caps and with a lot of fiddling of the controls, I finally have a picture of sorts.

https://www.youtube.com/watch?v=-nMNRP56N1Y

The vertical hold is very touchy and this is the best I can get for brightness and contrast. As this CRT had a brightener on it when I found it very possible this is the end of the line for the picture tube. Think there are any more gains to be made by working on it, or best to shelf it and start the search for a 21ALP4A?

Thanks all!

FK
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Old 08-18-2017, 02:56 PM
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If it had a brightener on it, it is that dim, and the CRT bias voltages and HV are in spec, then may as well put the brightener back on and see how decent of a pic it can make and for how long.

B&W CRTs prior to ~1960 were often not nearly as bright as newer CRTs we are used to seeing....That said it does look dim for a tube of it's era.

I may have a good spare 21ALP4. IIRC I sold one this spring, and I think I had 2 before then.

Since the vertical is rolling and the horizontal is stable I'd suggest checking the vert and sync separator tubes, checking all resistors in those stages and replacing any that are out of tolerance.
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Old 08-18-2017, 03:13 PM
old_coot88 old_coot88 is offline
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Get the set to working solidly first, then you'll know for sure that it's worth hunting a new CRT.
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  #8  
Old 08-18-2017, 07:50 PM
FrankieKat FrankieKat is offline
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Quote:
Originally Posted by Electronic M View Post
If it had a brightener on it, it is that dim, and the CRT bias voltages and HV are in spec, then may as well put the brightener back on and see how decent of a pic it can make and for how long.

B&W CRTs prior to ~1960 were often not nearly as bright as newer CRTs we are used to seeing....That said it does look dim for a tube of it's era.

I may have a good spare 21ALP4. IIRC I sold one this spring, and I think I had 2 before then.

Since the vertical is rolling and the horizontal is stable I'd suggest checking the vert and sync separator tubes, checking all resistors in those stages and replacing any that are out of tolerance.
So with the contrast at about 10%, the CRT voltages are on spec, though there's no picture at all until contrast is past about 90%. The B+ supply voltages are right on too. I don't have a HV test probe though so can't measure the HV unfortunately. I've been checking resistors and only have had to replace two or three, and the worst was maybe 25% off so clearly they used good parts.

Have tried a few different vert, sync and AGC tubes and have the best ones in there now, though there wasn't a huge difference. Both horiz and vertical lock are fairly poor and only get solid horiz lock with the control is the extreme end. It also seems to get worse as the set heats up.

Nothing I've done has improved or changed the brightness. Put the brightener back on for a little bit but improvement was minimal if any. That video was recorded in a pitch black room and it actually seems a bit brighter on the video than in person.

I'm going to keep grinding and checking voltages and components and see what happens.

Thanks for the tips!

FK
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  #9  
Old 08-18-2017, 08:41 PM
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That CRT will not be hard to find. The 21ALP4, 21CBP4, 21AUP4, 21BSP4 and others were pretty much used in all the mid-50 sets. I know for sure that Motorola, Silvertone and Philco used them in almost all their 21" models 1956-58.

Can you try a good CRT checker to be sure you can't give it a good bump?
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Old 08-18-2017, 10:09 PM
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Have you tried adjusting the Ion Trap? A slight misadjustment will kill the brightness.
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  #11  
Old 08-19-2017, 06:00 AM
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It could also be low HV... I've seen sets, especially B/W, where some incompetent repairman put a brightener on the CRT to try to fix a dim image caused by droopy HV.
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Old 08-19-2017, 10:36 AM
dieseljeep dieseljeep is offline
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That was one of the last good sets Westinghouse built! All the following models were cheap corner-cutting, hot chassis, PC board jobs. Some of the lower-end 21" models, didn't even have a voltage doubler, a portable chassis in a 21" console. They were minimal performers.
On Decades TV, they were running some old Westinghouse Studio One. On one Westinghouse advert, Betty Furness was extolling the virtues of the Gated Beam Audio Tube, that always insured perfect sound.
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Old 08-19-2017, 11:09 AM
old_coot88 old_coot88 is offline
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Quote:
Originally Posted by dieseljeep View Post
Betty Furness was extolling the virtues of the Gated Beam Audio Tube, that always insured perfect sound.
Hoo Ha! It was an elegant idea that lowered parts count and worked great until a bit of component drift set in.
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  #14  
Old 08-19-2017, 11:59 AM
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Quote:
Originally Posted by old_coot88 View Post
Hoo Ha! It was an elegant idea that lowered parts count and worked great until a bit of component drift set in.
At least some Westinghouse sets had the "quieting" or "buzz" control on the front of the set. If they were going to use the 6BN6, at the very least they should have made the quieting control a standard for the front apron. It needed frequent enough adjusting to justify it, that's for sure...
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  #15  
Old 08-19-2017, 12:23 PM
old_coot88 old_coot88 is offline
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Quote:
Originally Posted by benman94 View Post
At least some Westinghouse sets had the "quieting" or "buzz" control on the front of the set.
Ha. Didn't know that. L'arn something new every day.
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