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  #1  
Old 06-26-2015, 05:03 PM
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63bird 63bird is offline
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Need pointers on 65 zenith color roundie 25mc33

So its still original I never could tune in a picture just snow and audio.

I'm thinking now to recap it before doing anything else. At least all can caps and if there is wax paper which I have no clue if it does.

I've had this a few years now finally getting to try fix it. It seem the build quality is way better than my 63 roundie Magnavox with pcb boards. However the Maggie works great go figure.

So does anyone have schematics for this set?

Also what the best approach to getting this working properly again? You know the do's and dont's

I've fixed a few TVs trolling this VK site I'm still somewhat a newbie to TV repair. I'm good with building and modifying tube Amps and tuners just to give you some background.
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  #2  
Old 06-26-2015, 06:25 PM
DaveWM DaveWM is offline
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are you sure its snow and audio or blank raster and audio?

Unlikely to need a recap of any kind, if the HV is working the B+ is prob ok at least enough to trouble shoot the video.

could be tuner, try a new RF tube, make sure balun is not blown, get a video if possible makes it much easier to understand the issue
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Old 06-26-2015, 07:44 PM
zeno zeno is offline
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Time for screen shot. If you have good audio but "true"
snow it dont make sense. What it might be is the fine tuning
is off & the fine tune gears are no longer working. Set has a
super gold video guard tuner ( SGVG ) best anyone built.
You can pull it, take the cover off & be sure the screws on
the channel strips are being moved in & out. There is a gear
on the FT shaft that moves & engages the screws. This one
probably has the diaper pin style, a common fail.
Good luck

73 Zeno
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Old 06-27-2015, 03:50 AM
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Tubejunke Tubejunke is offline
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I have one about the same, but most of my problems were related to the horizontal efficiency coil going floppy and high horizontal output tube cathode current which can fry the flyback. I also had to replace the 3AT2 HV rectifier socket and bypass the resistor underneath. On these topics since you wanted pointers; my studies on old color sets in general is that the current I mentioned should be observed on a meter in series with the cathode (all current is measured in series). Some people place a .47mfd 600VDC cap in parallel (across the two meter leads) when making this measurement I believe to filter out unwanted AC and get a true reading. I'm not the best at explaining that. I have done it with and without the cap and got the same results.

I personally would run the set on a Variac or some variable AC line source at a reduced voltage. Since you have already been powering the set, you wont have to start at really low voltages working your way up. The old electrolytics in the power supply and other places along with paper or film caps have already proven that they can take the punishment of full line voltage. Feel the filter cans and/or carefully feel the smaller caps. They should all be cool to the touch. The set produces heat of course so I don't mean cold, just not hot. If one is suspect, look and see if it is positioned right near a tube. That may be the reason it is hot.

We all need a good tube tester, so look on Ebay for a decent tube tester that can test the compactron style tubes in there. Don't buy just a basic emissions tester if you are really interested in this realm of electronics. Clean your tube sockets and pins. Trust me on that one. You have the best old color TV type that you could get as far as build quality and flybacks that last IMO and that of many others. Good luck and post those screen shots so some of these real wizards can put you in the right direction!
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Old 06-27-2015, 07:36 AM
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Kamakiri Kamakiri is offline
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Originally Posted by Tubejunke View Post
I personally would run the set on a Variac or some variable AC line source at a reduced voltage. Since you have already been powering the set, you wont have to start at really low voltages working your way up.
Bear in mind that you'll need preferably a 10 amp variac. A 5 amp won't handle the load of a color set really well.
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Old 06-27-2015, 08:55 AM
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63bird 63bird is offline
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I'll have to do this when we get home from work. I do have it on a 10amp variac at 115vac I know for accurate measurements I should be at 117vac.

What voltage should I run it at?

My tube tester is a seco 107 I'm not sure if its good enough. I know there is way better though. What is a really good tube tester for TV repair?

I have a current checker that's for tubes using pin #8 and it can check current on tubes using pin #3 I believe it goes to 200ma it that enough?

I also have a bias probe I made to plug in to my meter.
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Old 06-27-2015, 10:20 AM
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63bird 63bird is offline
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Cool! This is the closest thing to a picture I've ever got.

It's not color, its on ch2

However I see those clusters of red, green, blue so I'm sure the guns are working.
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  #8  
Old 06-27-2015, 10:21 AM
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63bird 63bird is offline
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Is this more a Tuner issue?
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Old 06-27-2015, 12:10 PM
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Jon A. Jon A. is offline
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Quote:
Originally Posted by 63bird View Post
Cool! This is the closest thing to a picture I've ever got.

It's not color, its on ch2

However I see those clusters of red, green, blue so I'm sure the guns are working.
Haha, those guys. There's a 90s throwback.
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  #10  
Old 06-27-2015, 02:08 PM
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63bird 63bird is offline
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I like using cartoons for checking since I know how it should look. Yep thats beavis and butthead
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  #11  
Old 06-28-2015, 12:16 AM
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63bird 63bird is offline
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Is there a remote for this TV? If so which one would I need?
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Old 06-28-2015, 10:06 AM
MRX37 MRX37 is offline
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"Huh huh huh, hey Beavis, we're like, on a really old TV."

"Whoa! Check it out Butthead the screens all like, weirdly shaped and stuff!"

"Huh huh huh yeah, they like, didn't know how to make TV screens back then."
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Old 06-28-2015, 11:06 AM
DaveWM DaveWM is offline
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is the RF output on channel 2? generally its either 3 or 4 if you have a DVD or video tape player as the source.

lack of color could be as simple as miss adjusted fine tuning.
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  #14  
Old 06-28-2015, 12:45 PM
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63bird 63bird is offline
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It was on ch2, I'll change it to 3 and see if I can tune it in. My other roundie TV worked that way so I didn't think much of it.

I'm using a older Sony DVD player with the rf output.
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Old 06-28-2015, 01:14 PM
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63bird 63bird is offline
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MRX37 that's hilarious! They would see old musicans singing and make comments.
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