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 Post subject: "Dreaded" Silver Mica Disease?
PostPosted: Jun Wed 11, 2008 1:44 am 
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Why does everyone call it "Dreaded"? I thought it was pretty fun repairing IF cans. Sure, it takes time and patience, but its far from impossible to fix. There are other things that I dread more, like "dreaded mouse pee syndrome" or "dreaded broken dial glass, where am I gonna find another one illness" I'm sure there are others. Why is silver mica disease the only thing referred to as "dreaded"?


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 Post subject:
PostPosted: Jun Wed 11, 2008 2:01 am 
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While some are comfortable with doing that repair, it seems that many find it beyond their ability or understanding even though pretty clear photos of the procedure are available. The problem really becomes "dreaded" if you have an AM-FM set with 5 or more IF transformers, all needing to be rebuilt.

I agree there are worse problems, and that rebuilding IF transformers becomes much easier the more of them one has done. Radios with mouse damage or broken glass are better passed over for nicer examples, unless they are extremely rare models.

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 Post subject:
PostPosted: Jun Wed 11, 2008 12:03 pm 
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I just call it "dreaded" only because everyone else does. Actually, I believe the term "dreaded IF transformer silver-mica migration disease" was coined here by someone here at ARF and it just seemed to stick. It does seem like a dreaded plague that is so common among the legions AA-5 sets that exist.

Dave


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 Post subject:
PostPosted: Jun Wed 11, 2008 12:18 pm 
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I refer to the rubber covered wiring problem as "dreaded". I've only had one radio that I had to rework the IF cans on (Hammarlund HQ-100A boat anchor), but I've had lots of radios with rubber wire rot.

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 Post subject:
PostPosted: Jun Wed 11, 2008 2:01 pm 
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Location: Lake Lavon, Texas
As it does not qualify as a true disease, and it is hardly a scourge of mankind, then could it be one with a wry sense of humor that coined it.
If you are not aware of the condition, and spend hours chasing your tail trying to get that gremlin out of the signal path, only to find its something this simple ,you apply comic relief, and give it a name that brings a smile, after you fix the problem.

My most feared and dreaded disease is the out of cash to by more radios disease. :shock:

Rick


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 Post subject:
PostPosted: Jun Wed 11, 2008 6:06 pm 
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If IF transformer migrating silver mica caps bring on an intermittent problem, noise, ect then I would "dread" it for sure. Components that are missing or broken are easily recognized as such. Intermittents give me a fit.


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 Post subject:
PostPosted: Jun Wed 11, 2008 9:33 pm 
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I think we call it dreaded because we electronically upgrade a radio's electronics and clean up the body then, we give it a test run.
Oh no! We hear the radio play with that staticy sound. Don't bother testing anything else. You know what it is!


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 Post subject:
PostPosted: Nov Wed 24, 2010 2:31 pm 
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You guys that find it fun to rebuild IF cans should consider setting up shop and doing bunches for sale. Those of us with 8 tube Zeniths needing to have all or several replaced would buy some--for a fair price...
Better than installing NOS miller Ktrans that will do the same thing in a few years...

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 Post subject:
PostPosted: Nov Wed 24, 2010 3:07 pm 
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What Ive found with 50's AM-FM Zeniths is not SMD but voltage puncture of the dielectric. These are in decent size cans that come apart easy and repair is quick and painless.

The puncture is the dark spot in the very top in the photo below.

Now when you get to the 3/4" cans and a bunch of them in something like a Hammarlund HQ-170 or 180 then it becomes dreaded as its a slow process. Its not a task for a fumble fingers without good tools.

Carl

Image


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 Post subject:
PostPosted: Nov Wed 24, 2010 5:20 pm 
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OZ132HOME wrote:
You guys that find it fun to rebuild IF cans should consider setting up shop and doing bunches for sale. Those of us with 8 tube Zeniths needing to have all or several replaced would buy some--for a fair price...
Better than installing NOS miller Ktrans that will do the same thing in a few years...

Hear Hear! Yes those that find rebuilding IF transformers "easy" should put their money where their mouth is and offer rebuild as a service.
:)

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 Post subject:
PostPosted: Nov Wed 24, 2010 5:51 pm 
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I've repaired a couple of cans. You need the schematic, the EXACT replacement caps and good alignment equipment.
I wonder why it's called "Dreaded SILVER mica disease. There's no silver, just aluminum, mica and a brass rivet.
I don't think I would ever 'shotgun' all of the cans in an AM/FM receiver, just the bad ones. I've had radios that have two different types of IF cans. Usually only one would go bad.
Starting a "Dreaded silver mica disease" fix-it shop isn't such a bad idea. Probably not very profitable though.
Terry


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 Post subject:
PostPosted: Nov Wed 24, 2010 6:41 pm 
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There's only one condition that I truly dread about any gear I ever have to work on.

And that's the condition of "everybody-and-his-brother-got-in-there-first!"

Grrrrr! :evil:

L

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 Post subject:
PostPosted: Nov Wed 24, 2010 6:53 pm 
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BigBandsMan wrote:
There's only one condition that I truly dread about any gear I ever have to work on.

And that's the condition of "everybody-and-his-brother-got-in-there-first!"

Grrrrr! :evil:

L


That is truly worse than SMD and epidemic.

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 Post subject:
PostPosted: Nov Wed 24, 2010 6:55 pm 
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I've had some repairs where the previous tech was a total goober. I had one that took me weeks because I had to use the schematic to practically rebuild it.

I don't know about anyone else, and I'm not trying to hijack this thread, just make a comment; but when ever I fix a set, I try and use what I see to envision the last tech who worked on it.
Was he sloppy and just slapping some stuff in to get paid, or was he the type who took his time and made an effort to do a good job, no matter the monetary reward?
I can usually tell. I can see this older guy taking a sip of coffee, or setting down his cigarette, maybe his eyesight is like mine and he has to put on his 'reading ' glasses. He carefully picks the right part and uses his 200 watt iron to solder it in.
My grandfather was like that, and so was my dad. And I try my best to emulate them.
Terry


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 Post subject:
PostPosted: Nov Wed 24, 2010 8:00 pm 
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I always thought that it was derived from "the dreaded Lurgi (or Lurgy)" which was from an episode of the BBC Radio comedy show of the 1950s-1960s "The Goon Show", and made its way into the language in many English-speaking areas.

dreaded lurgy noun
[S] UK informal
a humorous way of speaking of any illness which is not very serious but is easily caught

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 Post subject:
PostPosted: Nov Wed 24, 2010 10:52 pm 
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Sounds like our "blue flu."

Very common among certain people at work, anywhere, anytime.

Especially the friends of friends.

L

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 Post subject:
PostPosted: Nov Thu 25, 2010 1:00 am 
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My hat's off to you Metzman. you enjoy working on old radios and find it challenging and rewarding and that's what it's all about. Sure some jobs are easier but what fun is that if you just slap a few caps in and it works perfect :P


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 Post subject:
PostPosted: Nov Thu 25, 2010 1:11 am 
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metzman wrote:
Why does everyone call it "Dreaded"? I thought it was pretty fun repairing IF cans. Sure, it takes time and patience, but its far from impossible to fix. There are other things that I dread more, like "dreaded mouse pee syndrome" or "dreaded broken dial glass, where am I gonna find another one illness" I'm sure there are others. Why is silver mica disease the only thing referred to as "dreaded"?

I've never understood the apparent aversion to mouse pee or turds by most ARFers here.

So many guys here, it seems, complain about it when a radio shows up with it.
So what? No biggie.
A quick whisk out and a wipe down solves it.

So what's the big deal?

Whenever I ever had to handle "yuckie" stuff like baby diaper drippings or kid puke or cat or dog "gifts"... I just stop and remember what my mother told me many years ago when I was a boy. She reminded me it's not a big deal by saying :
"That's what they make soap and water for".

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 Post subject:
PostPosted: Nov Thu 25, 2010 1:42 am 
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Pbpix wrote:
I've never understood the apparent aversion to mouse pee or turds by most ARFers here.

So many guys here, it seems, complain about it when a radio shows up with it.
So what? No biggie.
A quick whisk out and a wipe down solves it.

So what's the big deal?


Apart from having very corrosive effects one also has to think about hanta-virus carried by mouse pee....even old dried-out mouse pee.

All this stuff about cadmium, asbestos pads, selenium, solder fumes, pcb, etc is no reason to wear a haz-mat suit when working on an old radio but folks new to the hobby should be made aware that these things exist so that reasonable measures are taken to minimize exposure to anything that might be remotely dangerous. That's not worry-warting...its just common sense like 'don't stick your hand in a flame'.


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 Post subject:
PostPosted: Nov Thu 25, 2010 1:54 am 
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terrydec wrote:
I wonder why it's called "Dreaded SILVER mica disease. There's no silver, just aluminum, mica and a brass rivet.


SILVER is deposited on one side of the mica sheets to form the plates of the cap. You can see the silver deposits in Carl's picture. It is not aluminum.

Dave


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