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  #16  
Old 06-28-2015, 12:30 PM
MRX37 MRX37 is offline
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Quote:
Originally Posted by 63bird View Post
MRX37 that's hilarious! They would see old musicans singing and make comments.

Oh yeah I know all about Beavis and Butthead.

Seriously though your TV looks like it's 90% working. your color guns are definitely working and working in good balance, because you have good grayscale with no tinting that I can see. (Red, green and blue combine to make white in a color set)

Also your convergence looks pretty good.

About the only issues I see are the lack of color, and it looks like your vertical is shrinking. You might want to start troubleshooting capacitors.
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  #17  
Old 06-28-2015, 02:50 PM
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zeno zeno is offline
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First off the set is NOT a remote.
Looks like the CRT is still pretty good, good grey scale.

The no color may be just fine tuning or the DVD channel is 3 or 4
as mentioned.
As you FT you will start with no sound & poor B&W pix. As
you turn it ( usually CW) the pix improves & the sound comes in.
Go a little farther & the color pops in JUST BEFORE the pix gets "wormy".
Keep on going & the pix goes away but you still get sound.
If the set has AFT aka AFC turn it off til your done then put it on.
Almost all sets 1960+ had an adjustment for each VHF channel.
You can usually tune adjacent channels also, like on the #4 you
can FT down to #3 or up to #5

The vert problem on Zeniths is usually the vert intigrators.
Thats the next thing. After you evaluate the overall set to be
sure its fixable, good CRT etc always make the set as good a B&W as you can then do any color problems.

73 Zeno
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  #18  
Old 06-28-2015, 03:57 PM
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63bird 63bird is offline
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I'm on ch 3 now.

I notice color level must be all the way CW and a slight jiggle to get any color

Peak pix has no influence on the picture.

Brightness is all the way up

Contrast is all the way CW
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  #19  
Old 06-28-2015, 04:15 PM
DaveWM DaveWM is offline
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looks like a snowy pic

do you have a matching transformer on the ant? 300 ohm to 75 ohm.

dark pic is often a case of weak video out tube OR just not setup right (screen drives).

You should see if there is a service switch and go thru the setup procedure.

I assume you have checked the CRT and it test ok?

Brightness is best checked by confirming as follows:

Test CRT for emissions and cut off
check HV (25kv)
check voltage at CRT pins

if the above check out the CRT pretty much has to produce a decently bright pic. the CRT pin voltages will isolate where to look.

example, if the cathode pins on the CRT are too high a voltage (results in a dark pic), then you can go right to the video out tube. A weak video out tube (or a defect in the circuit making it not draw plate current) will result in too high a plate voltage at that tube. Since the set uses directly coupled cathodes (tied directly to the plate lead of the video out) the resulting high plate voltage at the video out is coupled to the CRT. The high CRT cathodes will essentially cut off the CRT (bias it off) making it too dark.

One more thing, this is the case, but if all looks good and you have a completely dark CRT then you need to check the focus voltage. if you lose focus voltage the CRT will be completely cut off. Focus voltage should be around 4.5-5.5 kv, best tested with a HV prob.
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  #20  
Old 06-28-2015, 04:44 PM
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63bird 63bird is offline
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The only crt tester I have is for B&W TVs. And I'm not convinced it even works right since it told me a tube i had was bad but it had a great picture.

I tried a different matching transformer it was only slightly better.

What's a good crt tester to get for these color roundies?
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  #21  
Old 06-28-2015, 05:13 PM
MRX37 MRX37 is offline
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"Hey Beavis, if we had a TV like this, we could like, pick up chicks. Lets take it home with us."

"Unhhhh ahhhh Butthead It's too heavy to lift!"

"Beavis you wuss. Here, let me do it. Unhhhh... Uh... This TV sucks. Let's go get some nachos."

"Yeah! Nachos! Nachos!"
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  #22  
Old 06-28-2015, 05:28 PM
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63bird 63bird is offline
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Like Todd's girlfriend lol.
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  #23  
Old 06-28-2015, 05:41 PM
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1st of all you have a vertical sweep problem. There is no better way to troubleshoot than to have the schematic and the proper test equipment, otherwise it's like throwing darts to find out what's wrong, depending on where you live, your public library might have the Sams Photofacts on file, they do here in South bend. As I always taught apprentices, check the basics first and then move on.
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  #24  
Old 06-29-2015, 04:04 PM
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DavGoodlin DavGoodlin is offline
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Could vertical shrink be that 50 mf cathode bypass cap on the 6HE5?

BTW, I have a 25MC33 and two more Zeniths of a similar vintage so Im paying close attention here. Right now Im just too busy fixing stuff for others...and here I go again.

Still need a schematic? PM me
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  #25  
Old 06-29-2015, 08:32 PM
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sampson159 sampson159 is offline
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check fine tuning belt.zenith has a small rubber belt on the fine tuning assembly.
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  #26  
Old 06-30-2015, 04:17 AM
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Tubejunke Tubejunke is offline
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I don't know how many times you are going to have to ask about the equipment you need. Cartoons won't fix it! LOL! Anyway, I found this thread right here at VK: http://www.videokarma.org/showthread.php?t=261808

It has a few good brands and types. Personally, my cheapest emissions only tube tester is the only thing I have with crt adapters. It's an Accurate Instruments tester, but it tells me enough. I would like to have one of the nice Beltron or B&K jobs mentioned in the thread above. Also, you have been asking about a tube tester. I am a big Hickok fan of test equipment in general, but they can be pretty pricey. However, it will be about the best built unit money can buy short of ultra high end jobs I have seen in the $Ks. With old test equipment you may find yourself UN-wantingly getting into restoration of that, so don't go on Ebay and find just any tester with a sweet buy it now price. Find one that has a seller who knows (or seems to) his equipment and can verify any claims of repair and/or calibration. Make sure the model you choose will test the types of tubes that you are interested in. One from the 50s isn't going to do your Zenith.

I ran across a B&K Precision 747B that I think would be a relatively modern, solid state tester that covers a LOT of tube ground. I got lucky and found mine owned by someone who thought that tubes no longer existed, thus a tester was worthless. WRONG! This tester will cost you a C or two, but supposedly worth it. Simple to use and is Mutual Conductance and measures in (GM) micromhos. A story within it's self, but it's how good testers test.
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  #27  
Old 06-30-2015, 07:46 AM
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63bird 63bird is offline
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Oddly I bought the same crt tester yesterday that's in that link. It's a sencore CR168 big mack.

I don't mind buying a good tube tester here soon. My seco tube tester has been fine for amplifier tubes. I rarely use it though. I've bounced between Hickok, B&K and sencore. There is so many models of each brand.

I'd like to get something thats cheap in price but does a OK job. If I can't find that then I want a really good one which I'd hope to get under $500.00 or about. I hate buying something then regretting I didn't spend X more for better.

Also for this chassis what are typical tubes that go bad? I'd like to buy extras for a rainy day.

I'm a Magnavox nut for thier console stereos. I have a nice stash to keep them going after in gone. I'm 32 by the way. I'm always trying to get younger people in to vinyl. So anything I learn during this process I plan to pass on.

Is there any good tech books I should read?
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  #28  
Old 06-30-2015, 08:12 AM
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DavGoodlin DavGoodlin is offline
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Quote:
Originally Posted by 63bird View Post
Oddly I bought the same crt tester yesterday that's in that link. It's a sencore CR168 big mack.

I don't mind buying a good tube tester here soon. My seco tube tester has been fine for amplifier tubes. I rarely use it though. I've bounced between Hickok, B&K and sencore. There is so many models of each brand.

I'd like to get something thats cheap in price but does a OK job. If I can't find that then I want a really good one which I'd hope to get under $500.00 or about. I hate buying something then regretting I didn't spend X more for better.

Also for this chassis what are typical tubes that go bad? I'd like to buy extras for a rainy day.

I'm a Magnavox nut for thier console stereos. I have a nice stash to keep them going after in gone. I'm 32 by the way. I'm always trying to get younger people in to vinyl. So anything I learn during this process I plan to pass on.

Is there any good tech books I should read?
The Tab Book in the center of this goldmine http://www.ebay.com/itm/HUGE-LOT-80-...item28026c3ab7
is the "Zenith Color TV Service Manual - Volume 1" by Robert L Goodman, it has most of the schematics and lots of service notes and information based on factory info.
This W A S my go-to book back when I started messing with color sets in 8th grade.
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  #29  
Old 06-30-2015, 10:52 AM
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63bird 63bird is offline
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Well looked like a lot of good info in there. So I bit the bullet and bought the lot. I'll probably cherry pick it then sell off the rest.

Thanks!
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  #30  
Old 06-30-2015, 11:04 AM
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DavGoodlin DavGoodlin is offline
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Quote:
Originally Posted by 63bird View Post
Well looked like a lot of good info in there. So I bit the bullet and bought the lot. I'll probably cherry pick it then sell off the rest.

Thanks!
Congratulations! That looked like the A-list of Sams Photofacts. Those 1975 and 1976 Sams master index are pretty useful.

If you want to sell off the rest, PM me. I like the antenna stuff, to the point of distraction.
When DTV broadcast was piloted here, about 5 years before analog shutdown, I bought a Samsung STB and started acquiring all manner of unused antennas to experiment.
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Last edited by DavGoodlin; 06-30-2015 at 11:10 AM.
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