Condensor mic Confusion

[drewl]

Got an Audio Technica AT813 Condensor mic that doesn't work.

It can run from phantom power or an internal AA 1.5v battery.

It has the mic element and no wires connecting to the little pc board which has a transformer, cap, 2K resistor and on/off switch.

If the AA battery is installed, the + end would make contact with a gold pin on the mic element. The - end would push down onto a spring loaded contact, pushing it through a plastic shroud which is to couple the signal.....how?

Osmosis?
The piece that protrudes towards the board doesn't touch the board, it's just near the transformer.
I tried connecting a lead to touch the protruding pin and got nothing.

Without a battery there would be no connection between the two sections at all!


There was a good bit of battery corrosion that may have annihilated wiring between the sections, I can't tell or see where there may have been.

Am I still insane? I don't see how this thing would work.

[Reader]

Can you post pictures of the thing?

[The Dude]

Yes, a picture or schematic would help. Without that and by your description, I imagine it's like an old school telephone circuit where everything is in series. But that's a bit of a guess. Something like this, maybe?

[drewl]

Okay, added pics to help decipher what's going on.

You can see the element, barrel where battery goes and pushes a gold pin up next to the pc board transformer and then out by the red and black wires go to pin 2 and 3 with XLR pin 1 ground as usual.

No other connections between the element and pc board especially with no AA battery installed, nothing connecting the sections.

[nevetslab]

Audio Technica 813

Okay, added pics to help decipher what's going on.

You can see the element, barrel where battery goes and pushes a gold pin up next to the pc board transformer and then out by the red and black wires go to pin 2 and 3 with XLR pin 1 ground as usual.

No other connections between the element and pc board especially with no AA battery installed, nothing connecting the sections.

I used to have one of these AT 813's, or may still have it (in storage). I checked to see if I had the data sheet, did, and see they clearly state it will run on phantom power without a battery installed. I've attached it, thought it doesn't shed light on the troubleshooting here.

at813a_english.pdf


I also had an image of an AT 33 condenser mic's battery compartment, which I believe is the same as the AT 813. The mic's FET amp is, I believe, in the space below the capsule grille assembly, where the cylindrical body begins, ahead of the battery compartment. I've never had that section open on mine.

[g1]

I would guess that the board had some kind of stiff wire that pressed against the (-) end of the battery and it either broke or corroded away?
Have you asked AT for the service info. sheet ?

[drewl]

I didn't think they'd have info like that.

I tried making a connection to that center pin to the board.
But again, with no battery installed the other end would not be connected to anything.