#16
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can you describe the failure mode of the fly a bit more?
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#17
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The fly is the last thing I would suspect in a zenith. Make sure you pull the cap off the hv reg tube first and verify its not over regulation or somthing like that. Looking at the schematic I see it has that complex shunt regulator with a bunch of high value resistors. Should be a fly282 and I bet he has it.
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#18
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Thanks for the response. Certainly, I shall share my current woe.
Fired up the set and checked basic voltages which appeared okay. I noticed the HO Tube began to red plate after a few minutes and there was no HV. Checked the H Oscillator and it was spot on frequency and amplitude to the HO Tube was correct and the HO Tube bias was about -60volts. I loosely coupled the scope to the HO Tube plate and saw a good spike. Removing the HV rectifier cap, I could draw only a small arc. I tried disconnecting the various things that might load the transformer such as the convergence assembly, the yoke horizontal coil and the HV would not rise. I measured the DC voltages on the plate and cathode of the damper and they were the same and there is no boost B plus. Incidently, I removed the regulator cap to ensure it wasn't loading down the HV. I finally did some resistance measurements and see there is about a 500k ohm resistance from the HV windings to ground. There should be no leakage from this winding to ground unless there has been a breakdown through the transformer frame itself. Funny as I tried ringing the coil earlier and it seemed okay. It looks like it will breakdown when powered up. All thoughts are welcome but it looks like the HO Transformer to me. Last edited by Penthode; 07-16-2012 at 11:09 PM. |
#19
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Its always easy to measure the screen, if its high the tube is overloaded, if its low its lack of drive.
I would agree the ring test can be pointless unless the primary is shorted. I took apart several rca ones to repair and rewax them, they all had the same failure, the hv winding was arcing from the top of the doughnut to the bottom with a big carbon trace from one end to the other. Zeniths seem to fail less because they are potted in that hard epoxy. From what you are saying I would try changing it. |
#20
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Quote:
That's quite an impressive repair to that leg- Great job! Magnavox300 |
Audiokarma |
#21
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WOW, what a nice job and woodworking for the replaced spliced leg!!
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julian |
#22
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oh good luck on this one .. she is a true survivor and I am sure she will payback all the loving care... and I am sure you will sort that HO.
__________________
____________________________ ........RGBRGBRGB ...colour my world |
#23
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I unfortunately struck out with Moyers. They were very helpful and did provide me the list of part numbers for replacements: Thordarson FLY-282, Stancor HO-629c and Triad d329. Does anyone know of an alternative source of supply?
On the other hand, I am not averse to ripping the transformer apart to examine what the trouble is. Has anyone ant experience removing the expoxy covering on these things? The search continues ... Thanks for the complement on the leg. My furniture repair knowledge was honed by a British book I bought thirty years ago written by Charles Haywood. He was an old time restorer and and the splice technique came almost verbatim from his book. |
#24
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That cabinet is looking might fine!!
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#25
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Wonder if there are still any good hillbilly areas? Ozarks have changed ,
Kentucky now dotted with WalMarts but still some old farms. |
Audiokarma |
#26
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Hope you can find a flyback. It is rare for a Zenith to have one go out, but....when I was a kid, my Uncle got a Zenith in on trade. Can't remember what chassis number, but it was the first Zenith rectangular set, so it was a 65 or 66 model. At the time the set was 14 years old. Altho the set came from a spotless home, and saw little use, (the chassis didn't have a speck of dust on it) the flyback was bad. He was going to junk it out, but the cabinet was so beautiful, and with it being a mint space command set, I took it. I had him put in a flyback, and discovered that the picture tube was bad. I had him put in a Zenith Chromacolor tube, and my parents got years of use out of it, before it finally died. Anyway... altho rare (my Uncle was even surprised the flyback was bad) it does happen, and I hope you can find a replacement for yours.
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#27
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Only saw two Zenith Flybacks fail, one in a smokers-tar encrusted 1969 23" chassis 16Z8C50 and my Aunt's bedroom set (no doubt left on all night) a 1970 14A9C29?.
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#28
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Quote:
It's also an incredibly beautiful area out there. I'd be living there if I could find a place I could afford. That Zenith will be a good performer. I wish you all the best luck with it. |
#29
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Not that I have one, but is the OEM part number S-71144 or S-65465? They both interchange to the replacement flys.
I bring this up because maybe someone has a pull that's sitting in a junkbox somewhere.... Check Talon Electronics too...http://www.talonix.com/shop/ |
#30
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Some of the Zeniths, I had problems with, where the terminal board would soak up moisture and affect the focusing on high humidity days. The transformer had to be replaced, as silicone or corona dope wouldn't help.
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Audiokarma |
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