[Boatanchors] micamold caps

[hwhall at compuserve.com]

I'm working on restoring some 1943ish Link Trainer electronics that used Micamold postage-stamp types. All the larger values (e.g., 0.01uF or larger) turned out to be bad & were paper types. By bad, I mean they failed insulation leakage tests badly. They looked exactly like your Midwest18-3630.jpg picture. All the very small values (down to 0.0005uF) were still good and I expect are real mica insulated caps.

If anyone has a bunch of Cornell Dub plastic encapsulated types (similar to Tiny Chiefs, etc.) I'm experimenting with how to extract the guts and unobtrusively restuff them with new components and I could use a few more "victims."

 

 Wayne
WB4OGM

 

-----Original Message-----
From: Adam Vaughn <adamant316 at verizon.net>
To: ranchorobbo <ranchorobbo at gmail.com>; boatanchors <boatanchors at mailman.qth.net>
Sent: Mon, Mar 21, 2016 7:09 pm
Subject: Re: [Boatanchors] micamold caps

>From what I understand, MicaMold made both real mica caps, and paper caps (as well as resistors!) in similar packaging. I think the paper types are generally wider than the real micas, which are usually 'postage stamp'-shaped (though some are rectangular, but fairly small - they will have six dots like the square micas, not four or five like the paper types). Here are some pictures of paper-type MicaMold capacitors:


http://antiqueradio.org/art/Midwest18-3630.jpg
http://antiqueradio.org/art/MicamoldCapacitor.jpg


And some actual MicaMold mica capacitors:
http://edsgoodstuff.com/edscart/bmz_cache/6/6764f610ddbe356e2777f89397a1992d.image.500x375.jpg
(note the rectangular one in the bottom row - I believe it to be mica)


More on identifying and replacing different types of capacitors: 
http://antiqueradio.org/recap.htm


Good luck!
 -Adam

 
-- 
Adam Vaughn
Collector of old computers, video game systems, radios and other electronic equipment... 
Visit my page at http://www.electronixandmore.com/adam/index.html
 
On 03/21/16, Rob Atkinson<ranchorobbo at gmail.com> wrote:
 
I am certain I have read or heard here and there over the years that
"Micamold" branded caps, are fake micas, actually paper dielectric
caps in a molded case made to look like genuine postage stamp micas.

Well, tonight I took a bad one I had pulled out of a rig and busted it
apart with a hammer, only to find what certainly appeared to be thin
strips of mica layered on top of each other and sandwiched into metal
grips, one on each end of the cap case and soldered to wire leads.
So, I don't know how anyone got the idea that these are not real mica
caps because the "micamold" that I broke apart certainly appeared to
be the real deal.

73

Rob
K5UJ
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