Crown PZM Power Supply Troubles

Hi all, I recently acquired a Crown PZM mic missing the transformer that converts 48V to 18V. I found the attached schematic online and after consulting David at Cinemag, I purchased a CMO-2.65/200CT. After following the schematic and building the circuit I don't get 18V! Is this schematic missing elements? Should I have gotten a different transformer? Any guidance would be greatly appreciated.

http://cinemag.biz/output/output.php

> . I found the attached schematic online

Where?

> I don't get 18V!

What DO you get?

I suspect the mike must be connected.

I recall there were two ways Crown PZMs were wired.

Thanks for your quick reply PRR! I also appreciate your encouragement to provide the whole picture!

The schematic I found was part of a .pdf document I believe was put together by Crown some years ago to supply info on there many discontinued PZM mics. While the link is dead on their site, I found it here: http://docsfiles.com/pdf_discontinued_pzms.html

As far as what voltage I am getting, none. I can measure 48V coming into the primary side of the transformer and ground, but nothing on the off of the connections label B+ and Ground.

Here is where I can thicken the plot. I have another PZM that is a complete set. It has a PX-18 Power supply which is the same as the PX-T except it can also take two 9v and supply power. It can also receive Phantom and drop it down to 18v. When I connect phantom to it, I get can get 18v without the mic connected. My conclusion is that with this type of supply the mic doesn't need to be connected.

> what voltage I am getting, none

Where?

The schematic is authoritative but baffling.

One thing I dimmly recall: some Crown PZMs, the mike-to-box cable WAS NOT GROUNDED. If you grounded it, you shorted-out DC power.

Here is _my_ best-guess reconstruction of Crown's drawing. The voltages may vary quite a bit. But there should be voltages *like* this at the places shown. Zero anywhere except _XLR_ pin 1 is a clue that something is shorted.