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Old 02-05-2017, 02:12 AM
Jon A.'s Avatar
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Run capacitor replacement

Okay, my daily watcher has been acting up lately and I think the run cap is on its way out. I pulled the back of the set and felt it; very warm, bordering on hot. It's a 3.5 microfarad, 440VAC oval can. I've been checking around and the closest oval can run cap I can find is 4 microfarads. I'm just wondering if one of these would be a suitable replacement.
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Old 02-05-2017, 07:50 AM
tvdude1 tvdude1 is offline
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Dumont set?
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Old 02-05-2017, 08:24 AM
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Originally Posted by tvdude1 View Post
Dumont set?
Or a Zenith Duramodule set? They used a ferroresonant supply with the cap. I my have one or two old-stock.
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Old 02-05-2017, 10:05 AM
zeno zeno is offline
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For the Zenith colors IIRC they are all the same.
Probably the same on other brands too.
Symptoms are if opened pulsating pix. Shorted
fast breaker pop.

73 Zeno
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Old 02-05-2017, 01:43 PM
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The capacitor used with a CV transformer forms a resonant circuit with the winding driving it. The value is critical to proper operation, so I would really suggest finding a 3.5 uF if at all possible.
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Old 02-05-2017, 02:25 PM
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Oh, I didn't know the type of TV mattered. It's my 1976 Electrohome C31 chassis console.

Seems to be a popular value for ceiling fan box-style capacitors, but oval cans are practically non-existent.
Quote:
Originally Posted by zeno View Post
For the Zenith colors IIRC they are all the same.
Probably the same on other brands too.
Symptoms are if opened pulsating pix. Shorted
fast breaker pop.

73 Zeno
LFOD !
Yup it pulsates a bit, mostly noticeable when looking closely at letterbox presentations. Often times it will pitch a fit and brightness will go down and back up repeatedly. Sometimes the picture will tear a bit. It was well-behaved for most of last night though.

Last edited by Jon A.; 08-25-2017 at 05:08 PM. Reason: Removed outdated link.
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Old 02-05-2017, 06:27 PM
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A separate winding and a two amp fuse for a couple of pilot lights ? Strange ....
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Old 02-06-2017, 09:54 AM
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A separate winding and a two amp fuse for a couple of pilot lights ? Strange ....
Allows for instant on - the winding for the CRT filament can be powered while the set is off. The lamps would need a separate winding.

I have an old stock Zenith - it comes with a mounting clamp as well.
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Last edited by Findm-Keepm; 09-29-2017 at 07:39 PM.
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Old 02-06-2017, 04:29 PM
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Quote:
Originally Posted by Findm-Keepm View Post
Allows for instant on - the winding for the CRT filament can be powered while the set is off. The lamps would need a separate winding.

I have an old stock Zenith - it comes with a mounting clamp as well.
Cool! So these don't go bad from sitting like electrolytics?

Ahh, so that's why there's a separate winding. This set has an "Instavu" switch on the back. I have it turned off though.
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Old 02-07-2017, 08:46 AM
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Cool! So these don't go bad from sitting like electrolytics?
Nah - They are hermetically-sealed and oil filled (hence the "no PCBs" label), and are not affected by aging as much as an electrolytic. These types of caps are in most every home air conditioning system - the one in my Rheem gaspack right now is a Zenith cap - put there while troubleshooting a no fan start problem (Cooling coil would freeze up). I swapped in the Zenith cap to replace a 4uF cap, but the problem turned out to be bad solder joints at a molex connector on the system control board. I was hot, so a quick resolder and then I buttoned it up once it was going - the Zenith cap left in the unit.
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Last edited by Findm-Keepm; 02-07-2017 at 10:57 AM.
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Old 02-07-2017, 02:52 PM
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Right on, and it will be good to know the Zenith part number in case the replacement ever goes bad. After all, this set is ran several hours a day.

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Old 02-23-2017, 04:04 PM
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Those Zenith Chromacolor II can capacitors (22-7126-01) are available from TEDSS.com. The only place I've been able to find them. It looks like Zenith contracted those out to York air conditioning. TEDSS says they're slightly dented. The two I ordered had tiny dents like there were a bunch stored loose in a big box, not crushed or anything.
http://www.tedss.com/2020038517
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Old 02-23-2017, 05:20 PM
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Quote:
Originally Posted by wb2mep View Post
Those Zenith Chromacolor II can capacitors (22-7126-01) are available from TEDSS.com. The only place I've been able to find them. It looks like Zenith contracted those out to York air conditioning. TEDSS says they're slightly dented. The two I ordered had tiny dents like there were a bunch stored loose in a big box, not crushed or anything.
http://www.tedss.com/2020038517
Thanks! I ought to get a couple of spares eventually. If my 23GC45 has one - I haven't looked closely yet - that's probably going as well. Right now my Electrohome has a couple of vertical lines on the screen at all times. The Zenith gets one on the right that goes away after a few seconds.

Last edited by Jon A.; 02-23-2017 at 05:23 PM.
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Old 02-23-2017, 05:50 PM
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Quote:
Originally Posted by Jon A. View Post
Thanks! I ought to get a couple of spares eventually. If my 23GC45 has one - I haven't looked closely yet - that's probably going as well. Right now my Electrohome has a couple of vertical lines on the screen at all times. The Zenith gets one on the right that goes away after a few seconds.
Those lines are not caused by the VRT resonant cap...All that cap does is regulate the AC output voltage on from the power transformer...The rectifier and filter cans would catch any noise the VRT cap could make.

Vertical lines are usually a horizontal problem, video problem, or bad filtering effecting one of those stages.
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Old 02-23-2017, 06:18 PM
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The Zenith is probably loaded with bad caps, including the VRT cap. Its picture is dreadful. I saw a video of the restoration of a similar one, also full of bad caps.

I suppose the next thing I'll do to the Electrohome is replace the two big filter caps just forward of the VRT.

Last edited by Jon A.; 02-23-2017 at 10:13 PM.
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