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  #1  
Old 05-02-2017, 10:34 PM
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Phil Nelson Phil Nelson is offline
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Emerson 609 projection TV

So, I'm chugging along, replacing electrolytic and paper caps in a 1949 Emerson 609 projection TV (on the left):



In addition to the usual wax paper caps, I see about a dozen of these little guys in white cases (ceramic or porcelain?). Some have wax gooping out the ends.



They have values (1500pf) in the mica range, the kind of thing I'd normally leave alone during the first pass.

Are these paper caps in sheep's clothing, or something more reliable? I would rather not shotgun parts unnecessarily.

Thanks!

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Old 05-02-2017, 10:44 PM
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Suspect caps; at the very least check a few by lifting one leg and testing it at/near rated voltage.

Plan on replacing them in any case. I'm even finding "normal" mica caps that are shot in '46 to '50 era sets.
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Old 05-03-2017, 12:31 AM
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For what it's worth, they're described as "ceramic" in the Rider's parts list, although I guess that could mean garbage paper dielectric inside a ceramic tube.

All (14!) of them occur in the audio & video IF sections, where they are used for bypass, AGC filtering, and decoupling, according to Sams. Examples: C6/C8, C10/C11, and C13/C14 in this schematic snip:

http://antiqueradio.org/art/Emerson6...io-VideoIF.jpg

I'm usually loath to replace a dozen of anything in the video IF, because . . . alignment.

Phil Nelson

Last edited by Phil Nelson; 05-03-2017 at 12:36 AM.
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Old 05-03-2017, 01:31 AM
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I think you'd better leave them alone. Even if they're paper types, the leakage should be insignificant with such small values.
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Old 05-03-2017, 08:40 AM
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Quote:
Originally Posted by Gleb View Post
I think you'd better leave them alone. Even if they're paper types, the leakage should be insignificant with such small values.
That may be the case with Russian made paper caps, but American made paper caps (and many Japanese caps) are crap...I've seen plenty of papers in that value range nearly dead shorted or leaking heavily even below 50V.
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Old 05-03-2017, 08:58 AM
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I can see "HI-Q" printed on the side. All the vintage caps I've encountered that look like that have been true ceramic and just fine. I'd leave them alone.
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Old 05-03-2017, 11:34 AM
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At that point in time I don't believe the state of the art even allowed winding paper caps that small? Well maybe, but they'd of been too expensive for consumer electronics.
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Old 05-03-2017, 12:08 PM
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Thanks, I'll leave 'em in peace for now.

These caps are definitely smaller than any of the TV's paper caps in that general range (.001, .003).

Phil Nelson

Last edited by Phil Nelson; 05-03-2017 at 01:23 PM.
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Old 05-03-2017, 01:34 PM
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I've found those in other sets and left them alone, they don't seem to be troublesome.

I suppose you could replace one and bust it open to see what it is inside.
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  #10  
Old 05-03-2017, 07:22 PM
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Here's the ceramic cap next to the smallest paper cap in this TV:



My Dumont RA-102 has a number of ceramic caps about the same size as these, but they have a different profile, more like a dogbone style resistor, and no wax dripping out the ends.

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Old 05-06-2017, 08:26 PM
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I see those all the time, and I've always left them alone.

In 30 plus vintage TV restorations I might have replaced one, and I didn't have to.
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  #12  
Old 05-09-2017, 07:24 PM
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After replacing the factory-installed electrolytic and paper caps on my Emerson 609, I'm looking at this big .25-mfd paper cap, evidently added by some sloppy repairman:



The cap isn't shown in either Riders or Sams. It's hard to trace things in this messy chassis full of long, wandering leads. But as near as I can make out, the guy wired this new cap in parallel with the Horizontal Size adjuster coil (L-8 in Riders):



Any ideas as to why someone would add this? Tacking stuff onto a width coil suggests an attempt to get more (or less?) width, at first glance . . . .

I normally remove mods and restore things to match the schematic, especially messy work like this, on the theory that the repairman was attempting a quick fix for some symptom that will be cured by the time I'm done recapping, etc. But if someone thinks this is a great improvement, I suppose I could try a new .25 cap there.

You can read the full schematic here:

http://antiqueradio.org/art/Emerson6...maticSmall.jpg

Regards,

Phil Nelson
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  #13  
Old 05-09-2017, 08:43 PM
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That is a width mod. I've seen .05 uF caps occasionally attached to RCA KCS-20 flybacks to fix a width issue.
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Old 06-03-2017, 03:43 PM
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Never cleaned a TV mirror but I have cleaned telescope mirrors, which I imagine are affected more by scratches. I use water and soap, a squirt bottle with warm soapy water blasted right on a chunk of smeg will usually get it off. Soak and blast. soak and blast. Garden hose type of pressure washer is good too. Just don't use anything in actual contact with the mirror. That seems to work well with dust/disuse build up.

I have also under duress used a super soft artists paint brush on a mirror that was really gunked. As it turned out the mirror was trashed but I didn't see any scratches from working it GENTLY with the brush.

You can get the mirror redone. If you look for places that make telescope mirrors you can sometimes have them do yours when they are doing another and save some dough. Can take a while that way. I had a mirror I home ground done that way, took two months but was cheap.
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Old 06-03-2017, 04:10 PM
pearsonk pearsonk is offline
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Make sure the cardboard/fiber shield is on the crt. From the pics, it looks
like the crt is not as far in as it should be [if memory serves me]. I always
use distilled water on these mirrors to avoid water marks after drying.
I have restored several of these Norelco units and have NOS 3np4s and a resilvered concave mirror........
Currently have a Scott and an Emerson with the Norelco system.
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