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  #46  
Old 11-07-2016, 04:19 PM
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Quote:
Originally Posted by Hagstar View Post
I have the answer- massive arc-over of the high voltage insulating cup under the high voltage rectifier. Ordered a new one.
Sometimes that can be fixed. I had a zenith color port set that arced through the bottom of the cup. My solution was to drill out the carbon arcing path then use Permatex gray silicone to fill in the hole...It worked well and was almost a free repair.
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  #47  
Old 11-07-2016, 05:28 PM
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This cup though was toast. I cleaned it with every solvent but carbon is deeply incorporated into the plastic over a lot of it.

We do have a cause of death here- severe arcing over the insulator cup blackened the whole bottom of the cage and overloaded the flyback system.

Last edited by Hagstar; 11-07-2016 at 05:36 PM.
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  #48  
Old 11-09-2016, 08:05 AM
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I find fixing vintage stuff there are these days that seem like weeks waiting for parts to come. This thing wanted to wake up but the old HV cup is like poison- catnip for anything that wants to arc.

I need the parts to come soon before I lose momentum. My CTC4 was on the bench a year like this.
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  #49  
Old 11-09-2016, 11:17 AM
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Quote:
Originally Posted by Electronic M View Post
Sometimes that can be fixed. I had a zenith color port set that arced through the bottom of the cup. My solution was to drill out the carbon arcing path then use Permatex gray silicone to fill in the hole...It worked well and was almost a free repair.
+1 - works every time. The Silicone Rubber has a higher volts/mil rating than the plastic in the cup - the cup will go before the patch!

RTV3145 is the best for HV applications - it's electronic grade, self wets, and cures in 6 hours or less. Navy avionics owes it's success to RTV3145 - it solved many arcing problems in F-14 (AWG9) radar power supplies, sealed chaff buckets, and I used it to cure arcing in a Conrac monitor used in the CATIIID bench that troubleshot modules. Great stuff.
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  #50  
Old 11-09-2016, 01:05 PM
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Quote:
Originally Posted by Findm-Keepm View Post
+1 - works every time. The Silicone Rubber has a higher volts/mil rating than the plastic in the cup - the cup will go before the patch!
+2 a similar repair is still holding in a 16" Zenith color portable. There was a full metal cap behind the HV rect cup, drilled out the pinhole the arc made and plugged and coated the cup bottom with black RTV.
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  #51  
Old 11-09-2016, 03:09 PM
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In this case though the entire cup is baked to a light brown color with spider webs of carbon deep in the plastic. Discharge paths cover most of the area around it in the cage.
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  #52  
Old 11-17-2016, 06:11 PM
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HOUSTON WE HAVE RASTER https://youtu.be/QniUxBgu3CY

John H.
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  #53  
Old 11-17-2016, 07:14 PM
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That's awesome news! Congrat's!
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  #54  
Old 11-17-2016, 10:07 PM
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Sweet! Looks like it is only an evening of adjustments away from a good picture.
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  #55  
Old 11-18-2016, 06:50 AM
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Nice!
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  #56  
Old 11-18-2016, 08:07 AM
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It looks like the set was fired up in a basement or garage with the copious dust I removed on it plus some moisture from a quick warm up. It had some latex paint rings characteristic of a Garage Period. My TV mentor Keith Park killed a TV once powering it up as a kid in the garage- an arc from the anode hit the cold glass.....boom.

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  #57  
Old 11-19-2016, 01:58 PM
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Odd symptom- high voltage takes 90 sec to appear at all, then over next minute or so builds but only to 21 kv. I am replacing 3.8 and 1000 ohm resistors under rectifier.

Interesting to note this was built at the factory with a rebuilt CRT. Philco got a lot of flak for this as I recall.

Last edited by Hagstar; 11-19-2016 at 06:03 PM.
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  #58  
Old 11-22-2016, 04:53 PM
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Fixed high voltage issues. Just rough convergence so far but finally an okay picture My next puzzle is that the AGC doesn't work though the pot seems to measure and function normally. Only just the right fairly weak signal makes an image, it overloads at the drop of a hat.

https://www.youtube.com/watch?v=Uj-wk-OtwzE

John H.

Last edited by Hagstar; 11-22-2016 at 09:53 PM.
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  #59  
Old 11-24-2016, 11:03 AM
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Thankful today for this forum- our little corner of the world for our bizarre specialty.

Does anyone know WHY Philco put over 100 volts on the early transistors in my set- in a signal chain where such voltages are dangerous and not needed it seems?
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  #60  
Old 12-30-2016, 06:11 PM
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Clues appreciated on the add warmup problem here- see video notes- https://www.youtube.com/watch?v=rLD2...ature=youtu.be
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