Hello Ann,
My guess is one of the transformer cores moved a little bit. I assume you have the plastic tuning tool? Try rotating each transformer 1/8 of a turn one way and then back to where it was. Do this one transformer at a time, testing in between.
Welcome to TW!
You put this EWS together yourself so you should be familiar with tuning, I would not go there quite yet. A photo of the insides and a sound sample might reveal something. I am curious about a loose wire near the oscillators in this home assembly that shifted position after the fall.
The whole board can be purchased for $96 or a non working theremin has a value of $150 to me for all the parts.
Bring it by my house, we are in the same state. That would be like driving across Europe to get here. (-:
Christopher
Thanks for the replies!
Christopher - Dutifully including links to a picture of the interior and a video showing the wobbly "beat" interference sound. My mistake, it's around C3, not C4. But I suspect it's also occurring higher, just inaudible. And maybe you can tell me if I'm crazy and this is just how an Ethewave will sound at this range. But I'm pretty sure it didn't before the unfortunate fall.
Pic:
https://goo.gl/photos/LtdRKnzfBs3DEbw78
Video:
Dewster - I have tried (and tried just now again to make sure) turning L5 and L6 back and forth to no avail.
Other things I've tried based on other postings - touching the audio output while playing, and checking my amp settings. These made no difference.
Thank you!
Ann
Ann, marvelous how you were able to put this troubleshooting package together. Tuning the L5 or L6 Osc transformers is not the issue. The theremin has 60 hz hum sneaking in from somewhere when I observe the tone with my method of listening. Let me think about this, could a crack in a track to a filtering capacitor have occurred? (crack in a track) <= now that's funny.
PS: The name Ann Marie tells me your mother had Catholic influence. Here on the reservation the Spaniards beat Catholicism into us long ago. (-'
Christopher
Idea-1: The theremin fell on the plug-in power connector with it plugged in and broke the ground connection loose at the circuit board? Are you plugging into an amplifier with a 3-prong power connector at the wall, this will solve this particular problem.
Ann, thanks for the video. I extracted the audio and the beat tone thing is happening at 120Hz, so as Christopher says, it's 60Hz from the environment getting in, possibly due to a bad ground. I'd take a look at the PC board where the power connector socket is, the ground connection there might have gotten damaged in the fall, or the solder connection on the board for the ground at that point might have broken loose. Do you have a multi-meter? If so, check resistance from the AC ground pin to the Audio ground coming out of the Etherwave.
My Etherwave was pretty sensitive to AC, if I put it too close to the wall where an AC wire was located it would intermodulate with 60Hz like crazy. Moving it away would help.
I'm glad you narrowed it down to a ground issue. I checked my pins and connector and they seemed fine.
I had already tried plugging it into two outlets, but just as a test, I moved everything to my kitchen and tried it in my GFCI outlet. (I began to suspect my outlet since I moved to a new apartment around the same time the theremin fell.) Suddenly, the wobble was gone. When I brought it back to the first outlet, the wobble returned, so the culprit seems to be in my wall, even though the multi-meter is registering a working ground in that outlet.
I found another outlet in my house (more convenient than the kitchen) that is not producing the wobble. Maybe it is closer to the house's ground or on another circuit. Who can tell?
The best news is that the Etherwave did not suffer any damage. You both have been so helpful!
Thanks a million, Christopher and Dewster!
Ann
P.S. I'm not Catholic. My mother let me choose my own middle name when I was four. Marie was my babysitter's name. :)
Ann, glad it's working out. Theremins are pretty much designed to be sensitive to AC electric fields, which surround us all in the form of house wiring. If I placed my EW near the wire inside the wall I knew (because I put it there) was feeding the overhead lamp and outlet, I could get all kinds of motorboat put-put sounds out of it. Moving it a couple of feet away made all the difference. This kind of interference is likely easy to deal with via digital notch filtering, too bad no one is doing so in any Theremin I know of.
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