Shure 545 Unidyne III Disassembly

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riggler

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Does anyone know how to get the capsule out of a Shure 545? I have isolated the problem in this mic to the capsule assembly, but am unshure -- ha ha -- of how to get past the rubber isolating material, etc.

Thanks!

Damian
 

Hasse

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A pic from Hanse'n audio:
Shure%20545S,%20545SD.jpg


Hope that could help.
Take a look on the switch. That has 2 tongues coupled by a moving magnet that shortcuts the signal to ground (if I remember right). Check that the tongues and the little magnet is ok.
 

riggler

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I got this far, but I need to get into inside the capsule assembly (the black tube piece with the grille on it in your picture). I know that the transformer and switch, etc, is all good on mine. I temporarily wired a 57 capsule to the body and it is working.

The capsule I have has no output, even when screaming into the capsule. My known good 57 capsule gives me about 3mV.

 

pH

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Riggler, you have to peel away the silver printed tape to expose a hole that holds the protrusions of a clip that holds the capsule head on. Push in the clip while prying the plastic cap up over it. Easy enough to get off but a pain to get back in! I think if you search SM57 you can find pics.

-Paul
 

Walrus

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Don't take off the top grille, there is a danger with an old mic of ripping the whole diaphragm off of the magnet assembly.
To get inside the plastic sleeve, de solder the terminal bases with a solder sucker to free the wires that come up from below. Then undo the nut holding the paxolin board and with care the sleeve should slide off.
You will now see where the wires come from the voice coil and are soldered to another paxolin board. If you are lucky, one of them may have developed a dry joint over the years, and re soldering them may make it work again. But most likely, one of the very fine wires will have snapped off. This usually occurs when, over time, people have twisted the assembly around within the sleeve and the board works loose......
 

riggler

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I removed the top nut and washers, and the phenolic board. Now I am faced with another nut that does not seem like it wants to come off. Are you saying that this nut should stay on and I should try to pull on the screwthread, and rubber material, out of the plastic sleeve?

Or does this second nut also need to come out as well? I did not want to force anything. Thanks!
 

12afael

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if it is like a sm57 and it look like it, the first nut is enough then you have to pull it off with some strength because the rubber attach it. you don`t need to peel the silver plate you can put a knife or a clip to release the inner washer.

post pictures of the membrane maybe I can help
 

Walrus

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As 12afael says, the nut underneath stays on, but may take some carefull pulling to get the sleeve off.
I still recommend not taking the grille off unless really necessary, as it is very easy to damage the membrane.
 

Walrus

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Camera now charged.
First pic shows cartridge without sleeve.(Actually a 565 cartridge but the principal is the same)
In second pic you can see where the wire joins the terminal. It's here where there could be a dry joint, but also it is here where the wires often break if the mic is twisted a lot.
 

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riggler

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Hi, this helped a lot! I got mine apart. I retouched both solder joints, don't see anything broken anywhere. I looked at the diaphragm and am able to see the leads go right into the voice coil. There has to be a tiny break somewhere that I can't see. Argh!
 
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