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 Post subject: Re: Westinghouse H892T17 B&W TV Restoration
PostPosted: Dec Tue 03, 2019 4:01 am 
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David Child wrote:
So, 1st slow start had mixed results. All board tubes have filament voltage, nothing exploded (always a bonus) but no filament voltage to the 2 tuner tubes or CRT. Those are #3, 2 and 1, the last in the chain, so I need to check between tube #4 and tube #3.

If all but the last 3 tubes are lighting, you may have a short to ground at the 3rd from last tube in the string. This puts a little more voltage on all the rest, but they probably won't be noticeably brighter than usual.

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Mark Nelson
A collector of TV signal boosters and UHF converters -- God help me!
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 Post subject: Re: Westinghouse H892T17 B&W TV Restoration
PostPosted: Dec Tue 03, 2019 5:46 am 
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Joined: Sep Mon 28, 2009 1:53 am
Posts: 327
Location: Bloomington, IN, 47401
thomas13202 wrote:
what exactly did you get on the crt when you powered the set on? was there any sound? a no sound no raster problem points to low or no b plus voltage. if you got sound but no light on the crt that would be a problem in the high voltage or horizontal section. if you got light on the crt but no sound that would be a problem in the audio section. dont forget all you will get without a converter box or dvd or vcr hooked up is static sound for audio and light and snow for video since old sets are not capable of recieving modern digital tv signals without a converter box.


I knew I needed an NTSC signal, so I had an old VCR running to an RF modulator connected to the VHF antenna jacks.

I got an image but it was distorted. Can't remember if I had sound or not.

Anyway, I got the issue with the filaments worked out. All tubes have power and show some glow.

The problem now is that when I bring the voltage up to 90v or so, tube 12BQ6BA, going to the flyback, started to show a blue glow and the tube got VERY hot. No indication of HV from the flyback and nothing on the CRT.

Otherwise, no caps popping and no resistors burning up.


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 Post subject: Re: Westinghouse H892T17 B&W TV Restoration
PostPosted: Dec Tue 03, 2019 4:05 pm 
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Location: Pewaukee, WI
How did you get an image if there is no HV and nothing on screen?

Blue glow in a power tube is normal. Purple indicates a gassy tube. Output tubes tend to get burn your fingers if you touch them hot. If the plate structure of the tube starts to glow a dull red (or worse yet a brighter color) in the dark that means the output tube is drawing excessive current which is bad.


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 Post subject: Re: Westinghouse H892T17 B&W TV Restoration
PostPosted: Dec Tue 03, 2019 8:05 pm 
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Joined: Sep Mon 28, 2009 1:53 am
Posts: 327
Location: Bloomington, IN, 47401
Electronic Memory wrote:
How did you get an image if there is no HV and nothing on screen?


That was before I started the refurbish. Go to the "Antique Radio Discussions" forum and look for the post titled, "
2nd Score in Two Weeks!" Scroll down a bit and you'll see the Westinghouse with a very distorted image.

Now I get nothing; no snow, no static.


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 Post subject: Re: Westinghouse H892T17 B&W TV Restoration
PostPosted: Dec Thu 05, 2019 2:07 am 
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Joined: Sep Mon 28, 2009 1:53 am
Posts: 327
Location: Bloomington, IN, 47401
David Child wrote:
So, anyone have a schematic for the H892T17 (V) model? SAMS does not.


Really need that schematic right now!


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 Post subject: Re: Westinghouse H892T17 B&W TV Restoration
PostPosted: Dec Thu 05, 2019 3:12 am 
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Joined: Mar Sun 01, 2009 10:27 pm
Posts: 5045
Location: Ann Arbor, MI
While waiting for someone to find a schematic...

It sounds like you have no B+ voltage. That looks like a voltage doubler power supply. Look at the wiring from the power plug up to the rectifier diodes. See if the power goes through a power resistor of something like 5 to 10 ohms. If found, see if it is good. Check the fuse. If is looks like it violently blew up inside then there is a short or the rectifier diodes (if replaced) are installed incorrectly. If it looks like it just gently opened up then perhaps the fuse just got tired. If necessary we could come up with a generic schematic for a voltage doubler power supply. Some of the photos you posted show a fairly good view of the power supply. You could use that to check the polarity of the rectifier diodes. There should be at least one electrolytic cap where neither end is connected to circuit ground.

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 Post subject: Re: Westinghouse H892T17 B&W TV Restoration
PostPosted: Dec Thu 05, 2019 3:24 am 
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Joined: Sep Mon 28, 2009 1:53 am
Posts: 327
Location: Bloomington, IN, 47401
Will make those checks.

One thing I know I'll need is a 41 ohm 20 watt resistor. An odd value! The current one measures about 230 ohms. If anyone has one in their parts bin, let me know.


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 Post subject: Re: Westinghouse H892T17 B&W TV Restoration
PostPosted: Dec Thu 05, 2019 5:02 am 
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Joined: Sep Mon 28, 2009 1:53 am
Posts: 327
Location: Bloomington, IN, 47401
I couldn't find the schematic at Steve Johnson's site because he had just 1 hard copy left and didn't list it.

He sold me that last hard copy, so I should have something to work with by the weekend.


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