Mighty Slim
9 posts
May 20, 2014
5:21 AM
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The original element in my 1990s vintage Hohner Blues Blaster began to fail, so I screwed up my courage and undertook to repair it myself. The original element was an Astatic MC-127. I obtained a Shure 99A86 CM element and installed it using the original gasket. Mic works but I have two questions, if anyone can help.
First, I think I have read elsewhere that such a change requires a new volume pot of different resistance. Is that true and if so, what pot should I look for and where should I look and is there any way to screw up the wiring ?
Second, do I need a new gasket ? The element seems to fit in the old gasket and the mic works, but I have never done this before and am afraid of what I do not know.
Thanks
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arnenym
288 posts
May 20, 2014
6:30 AM
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The pot have a marking that says what value it have. If it is a 5M you have to change the pot.If it is a 500K it's okey to have it left. I don't know where to find replacements to those pot's, they have a very long shaft.
Google on "harp mic gaskets" and you gonna find a company where you can buy a new gasket fitting Jt 30 shell and a CM element.
Last Edited by arnenym on May 20, 2014 6:31 AM
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Wendell
25 posts
May 20, 2014
7:10 AM
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For best results when converting from crystal/crramic to dynamic, I change the pot and the gasket. At 1Meg Ohms the pot will act more like an on off switch. A value around 250k Ohms suits the Shure cm.
The Shure is slightly smaller than the Astatic, so the original gasket will not keep it snug in place.
Last Edited by Wendell on May 20, 2014 7:13 AM
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Mighty Slim
10 posts
May 20, 2014
9:02 AM
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Much obliged for the advice. Thanks
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barbequebob
2562 posts
May 20, 2014
9:55 AM
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Many of the 1990 BB's had 250K pots in them stock and the ones under the Astatic name had 500K pots as stock, and this was info that I got directly from Astatic, who were making them both at the time. Those pots are very common with electric guitars so it shouldn't really be a problem finding one.
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Sincerely,
Barbeque Bob Maglinte
Boston, MA
http://www.barbequebob.com
CD available at http://www.cdbaby.com/cd/bbmaglinte
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