New Etherwave Problems

Hi all,

I hope you can help me out. I just received a new (to me, hardly used) Moog Etherwave Standard Theremin the other day. This is my very first time attempting to use a theremin, and I have yet to get it working right. I now have it set up on a stand in the middle of the room, a few feet away from any nearby objects. I have it connected to a pair of computer speakers via a 6.3-3.5 converter plugged into its Audio out port. This is the third playback device I have set it up with and I am getting the same results out of the theremin, so, while not ideal, I don't think the speakers I am using are the cause of the problem. When I switch in on there is a little wobble noise and then a constant high tone. The volume antenna seems to work fine...I can set the audio knob to the point where I can silence it gently by placing my hand about two inches from the volume antenna. It seems like the pitch antenna, on the other hand, isn't doing anything...the pitch knob only changes the pitch from very high, when it is all the way anti-clockwise, to quite high all the way clockwise...it probably only changes an octave at both extremes. There is no change in pitch no matter how I move my hand in relation to the pitch antenna...is it broken?

This might be a very common error and an easy fix, or it might be wrecked, I don't know.  I've tried to give all the information here but if you need to know anything else I can try to tell you.

Thanks,

Robert

What's your level of electronics expertise?  And do you have access to a DMM or scope?

If you mean opening it up and getting involved with the circuits and wires...not very much. I have a soldering iron from when I was toying with some very basic led circuits and some experience from school (though that was a while ago). So...I could probably have a go if it was something extremely simple...but I would be weary of completely ruining this fairly expensive thing. I don't think I have access to either of those things...I'm assuming that second thing is an oscilloscope...I have no idea what the first might be.

DMM = digital multi-meter - for measuring volts, ohms, current.

Thierry can help you better as he has likely fixed truckloads of these things, but I'd check (with a DMM) for continuity through the pitch side EQ coils, and would check (with a DMM) the voltages on the pitch side transistors to see if anything is blown.  This is old technology stuff, so you might be able to fix it.  Moog also offers a complete board of new guts pretty reasonably.  Is it under warranty?

Hello Book,

When you mentioned the computer speakers it always raises a red flag. Theremin's need a good earth ground from somewhere to work properly, usually through the audio cable to a 3-prong earth grounded amplifier. The EtherWave use to come with a wall wart with 3-prongs. If yours does not have this it is simplest to just plug into a properly ground amp.

If you pull off the cover I am afraid you will be in over your head, maybe.

Christopher