Broken Theremin - Help needed

Last night I sold my old Etherwave Standard. We checked that it worked correctly, but as I packed it it slipped my fingers, and one end (the volume end) fell approx. 2 inches down on the table.

I took no notice of this, as it have seen worse in my ownership, but when the new owner tried to use it today, it is completely dead.

We opened it but everything looks OK, no burnt smell, no loose or damaged components. I checked the power on the solder points towards the back, and it holds 12 V when povered.

What could cause this? Anyone with a suggestion about what to check? I have cancelled the deal, but promised to see if I can fix it, as the buyer still is interested.

Hope you can help me.

Best regards.

/Andy

Hi. It's possible that the tuning lug has been bumped out of tune. You might try retuning it. To do so, open the theremin, and look at the board. There are three silver cube shaped devices mounted on the board. Each has a hole in the top. You want to adjust the one that is on the left (L11..corrected). This is the volume tuner. Use ONLY the plastic tool that came with the theremin to adjust slowly. Depending on the age of the theremin, you'll either use the flat, or hex end of the tool. Insert the tool, and slowly turn the lug. You should hear sound return.

While you're at it, this might be a good time to retune the theremin's pitch side as well. :)

Thanks, I will look into that when I come home tonight. I really hope it is something as simple as that.

/Andy

The volume tuning coil is L11!!!

Out of that it may also be that thanks to the bumping one of the three big linearization coils on the left (volume) side of the circuit board is broken. This can be checked with a multimeter. One of the coils should have around 15Ohms, the two others 8Ohms each.

Thanks again, I now have several things to check, and hope one of them is the problem.

If something is broken, where can I get spare parts in Europe? Is there somewhere that can do the repair for me?

/Andy

Andy, you may contact me by mail theremin[at]tfrenkel[dot]com

I have a small theremin hospital in France and people from the whole Europe and sometimes from the U.S. send me their defective instruments in for tuning, repair, upgrades or individual modifications.

Here, just as an example, an excerpt of an email which I received today:
[i]Hi Thierry, many thanks for doing such a fine (and quick!) job of repairing and setting up my Etherwave theremin. It arrived safely today and it plays much better than ever before![/i]

In another post it is discussed that the Theremin is no more than a VLF radio receiver, but after trying to sell mine, I do believe it has a soul.

The buyer tested the Theremin on two different pieces of equipment and outlets, and I have seen his setup, it is nice stuff. I tested it this morning, at his place, with my Micro-Cube. No sound.

After returning from work tonight, I powered it up to warm up before trying your suggestions, and after a while I connected the amp. Out came the usual sounds from touching the amp, and as I went to the Theremin everything worked as normal.

What do the experts think is going on here? Did my Theremin not like to be sold? How can I prevent this from happening again?

/Anders

Anders,

I know exactly what you are talking about, is it mere coincidence my friend?

[i]O day and night, but this is wondrous strange!

And therefore as a stranger give it welcome.
There are more things in heaven and earth, Horatio,
Than are dreamt of in your philosophy.[/i]

Thierry, that sounds a little familiar?