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-   -   FS: 1970 14" Zenith A3520. Parts/Repair. (http://www.videokarma.org/showthread.php?t=269607)

Freon 10-05-2017 08:23 PM

FS: 1970 14" Zenith A3520. Parts/Repair.
 
THIS THREAD IS OUTDATED IN EVERY WAY. I've kept it here for archival purposes. If you are interested in this (NOW WORKING!) TV, please refer to this new thread.

$10. All American, HEAVY Zenith color vaccum tube 14" TV from 1970, possibly 1969. Model no. A3520. Chassis no. 12A10C15. All knobs, handle and both antennas intact. No cataracts on tube, only one tiny scratch in the middle. But it doesn't work.

Photo album: https://imgur.com/a/BoDtR

I rescued this from an e-waste dump today and hoped to try and get it working. It wasn't til I finally got it back to my dorm I realized what I had was a genuine tube TV. Tube equipment is far beyond my repair expertise so I wish to sell this to an enthusiast who knows what they are doing and can repair this or use it for parts. Hopefully there is somebody out here. I will also trade for any working 19" color CRT TV with knob tuning (heck maybe even varactor), from any era, as I've been looking for one for quite some time with no luck.

I tried turning it on only once. I saw tubes glowing orange in the back, 30 seconds later very loud screeching noise varying in pitch. Occasional sputters of snowy picture. I saw small arcing somewhere near the bottom on the back of the CRT, probably the cause of the noise. Not near the flyback, though.

There are several empty tube sockets on the board. Probably had tubes taken out, though certainly not anytime recently as it's pretty dusty inside. Maybe that's all it needs.

I am located in Normal, IL, on ISU campus. Please PM me if you are interested.

Adam 10-05-2017 08:35 PM

Hi, I'll give you $10 for that. (Although, I can't pick it up until the weekend after next.) I do also have a 19" knob tuned b/w tv I would trade, if you'd rather trade. Sending pm...

Sandy G 10-05-2017 08:47 PM

Sorry that you felt it was beyond yr skills as a repair guy, but kudos that you elected to save it,& pass it along to someone else.

Electronic M 10-06-2017 09:18 AM

That is a nice set. If Adam passes I'd be happy to buy it...I might even offer double or triple your asking price. :D

Figures this gets posted in the middle of the worst shower I've ever taken (power went out and stayed out right in the middle leaving me standing there in the dark).

dieseljeep 10-06-2017 11:58 AM

Quote:

Originally Posted by Electronic M (Post 3190310)
That is a nice set. If Adam passes I'd be happy to buy it...I might even offer double or triple your asking price. :D

Figures this gets posted in the middle of the worst shower I've ever taken (power went out and stayed out right in the middle leaving me standing there in the dark).

At least the water didn't turn cold! Now you know how Stevie Wonder showers. :scratch2:
I have a little newer model than that one, using the HV focus voltage CRT. A little better picture.

maxhifi 10-06-2017 12:11 PM

I bet it's the focus voltage divider arcing. You can still buy a new one, it's a fairly easy repair. That's very similar to the 17 inch Zenith which was my first TV. Tube stuff isn't so hard to work on as you may imagine, I have a much easier time with it than I do with solid state equipment. That TV is fairly rare and a good save.

Freon 10-06-2017 01:36 PM

Quote:

Originally Posted by Sandy G (Post 3190299)
Sorry that you felt it was beyond yr skills as a repair guy, but kudos that you elected to save it,& pass it along to someone else.

Quote:

Originally Posted by maxhifi (Post 3190314)
I bet it's the focus voltage divider arcing. You can still buy a new one, it's a fairly easy repair. That's very similar to the 17 inch Zenith which was my first TV. Tube stuff isn't so hard to work on as you may imagine, I have a much easier time with it than I do with solid state equipment. That TV is fairly rare and a good save.

Believe me, I'd love to restore this set myself, but I don't think I could do it justice. I haven't touched tube equipment in my life. I don't have the equipment, no tube tester, CRT tester, oscilloscope etc. It's near impossible to get any of that stuff here in this rural college town, unless I spend hundreds on eBay. And the schematic is either nonexistent or costs $22 on SAMS. That and I'm running out of space in this tiny dorm.

Electronic M 10-06-2017 02:11 PM

Copmactron type tubes (except for horizontal and vertical outputs) are dirt cheap. You could get a few sets of tested replacements cheaper than a low end tester, and test tubes by substitution.

If the CRT lights over most of it's face and is reasonably bright a CRT tester is not needed either.

If your in a college town and there is an electrical engineering, computer engineering, Physics, or other scientific/technical curriculum there will be a lab with an oscilloscope...Getting permission to use it would be the thing. Scopes are often not necessary on sets this new.

I've got a nearly complete library of Zenith issued Color TV schematics from the beginning to the end of the modular upright solid-state chassis, and some full service manuals from that time. If you want I could copy the schematic for it and mail it to you (I'd offer some form of digital copy but I'm neck deep in computer troubles presently.).

IIRC a friend of mine had me service the same chassis in a different cabinet. His was arcing loudly from the HV cage due to one of the screws that held the rectifier socket in arcing through the insulator cup to the chassis. I ended up cleaning the cup, drilling the carbon tracking out of the cup filling the hole with RTV silicone, cutting the screw down to a shorter length and putting it back together...The repair has held up well.

Freon 10-06-2017 04:01 PM

Alright, well thanks to the encouragement of several, this item is no longer for sale. For now, at least.

I finally mustered the courage to take a crack inside of the thing. Gave it a dusting, made some observations. I will make a thread in Rectangular Screen Tube Televisions with more info.

WISCOJIM 10-06-2017 06:43 PM

Quote:

Originally Posted by Freon (Post 3190318)
And the schematic is either nonexistent or costs $22 on SAMS.

Just ask for Sams 1067-2 here, someone likely has a copy for you.

.


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