Elysian Theremin Power Supply

I do not recognize every component, if you can tell us the voltage regulator ID/Number we might tell you the best power supply. A lot of people get their earth ground by just plugging into an earth grounded amplifier that has a three prong plug. With the audio amplifier on board I do not think Q7 is it next to C42 in the middle of the board, that would be too wimpy, looks like a transistor.

It looks like that 1 amp diode near the power cord is for polarity protection and the unit must be powered by a regulated DC supply. That would make things awkward for an effective power supply with earth ground. 

Edit: Maybe I should look at that schematic down below, use a 15 volt dc regulated supply. Get your earth ground from an amplifier with three prong plug

Christopher

"Here is the schematic and manual:
uisoftware.com/PAGES/links_images/elysian 2014.png
uisoftware.com/PAGES/links_images/_Elysian Theremin Owner's Manual.pdf"  - Kalib

Wow, thanks for those!

I've just read that the unit must be Earthed. I'm assuming this the same as grounded in the US. Since I'm using this adapter https://www.amazon.com/gp/product/B015H0UPWU/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1 perhaps the lack of a ground plug is causing the issue.
Will look about for one...
K
p.s. I tested the old power supply that was causing hum, and it was 19volt not 15v so that may have been the source of the hum issue. It is grounded but did not produce audio out in Washington as it had in California. I've checked the wall ground is good.

The schematic shows the power regulator crossed out.  So, unless I'm missing something, you should probably use a 15V well regulated one.  And ground the Theremin via one of the audio jacks or something.

From your pix (thanks for those too!) it looks like the LM380 is socketed, not soldered.

Also, you should be aware that Christopher can't read or write schematics, and barely understands electronics in general.

Update:

Dear Kalib,
I'm afraid your Amazon power supply will be no good for a theremin. Theremins need a low radio-frequency (RF) noise linear power supply. Switch-mode types (like the Amazon) will just make a horrid noise. If the original power supply measured 19V that would suggest it was un-regulated.  This may mean your theremin has an internal 15V regulator.
I still think you have some kind of speaker amp fault. Try unscrewing the speaker underneath and taking the front panel off. If you or you technician get stuck you may have to send it to me.
Regards,
Jake

Kalib, maybe I'm blind, but I don't see an obvious 15V regulator in your pix.  Though the 19V supply does rather strongly suggest that regulation would be somewhere in there.  A linear regulator board would be a simple thing to add if it comes down to that.

Be careful of advice from people that have never demonstrated anything that works properly.

IMHO your best cost effective approach is to use one of those 13.8 vdc 120 to 12 volt converters popular for powering CB radios back in the 80's.

You do not need more than 1 amp, higher is ok.

look on ebay

Excellent on Amazon with earth ground

My own theremin design solves all theremin design issues and has the most beautiful of sound. Mine uses AC DC or Switching with on board regulation.

Did you know a beautiful theremin sound is just $5 in parts and special knowledge that eludes engineers.

Christopher
www.Hwy79.com

Note: Another factor is, I think this was the first Elysian ever made so the schematic and manual may be a bit off. For example, there is not Ring Mod switch on this unit.

"Note: Another factor is, I think this was the first Elysian ever made so the schematic and manual may be a bit off. For example, there is not Ring Mod switch on this unit."  - Kalib

His emails do seem to be rather out of sync with what you have there.  Do you know how many of these were made?  Interesting that you may have the first one.

"Note: Another factor is, I think this was the first Elysian ever made so the schematic and manual may be a bit off. For example, there is not Ring Mod switch on this unit."  - KalibHis emails do seem to be rather out of sync with what you have there.  Do you know how many of these were made?  Interesting that you may have the first one.

Yeah, the friend who gave it to me, says the friend that gave it to them, was given it to them in the mid 90's by a Adam Fullerton after one of his friends knocked it over on stage and scratched it up. The power supply they used was a custom job for the US but always produced some line hummm. I think it was assumed this was due to the fall and damaged. Anyhow, they knew I had an Etherwave and Theremini so figured I might be able to do something with it.

I figured maybe it was a bad power supply, and started there. Even adding the 15volt 2A ungrounded supply gave a clean signal out the line out so I'm hopeful, but I've returned that to Amazon per Jake's reply. Tho' again it didn't make a "horrid noise" so I'm puzzled. Off to find a "low radio-frequency (RF) noise linear power supply" I'm hoping that is not costly or a Google search Unicorn.

Kalib

p.s. Latest from Jake

"Dear Kalib,
I'm afraid your Amazon power supply will be no good for a theremin. Theremins need a low radio-frequency (RF) noise linear power supply. Switch-mode types (like the Amazon) will just make a horrid noise. If the original power supply measured 19V that would suggest it was un-regulated.  This may mean your theremin has an internal 15V regulator. I still think you have some kind of speaker amp fault. Try unscrewing the speaker underneath and taking the front panel off. If you or you technician get stuck you may have to send it to me.
Regards,
Jake"

I found this: Seems to be on the mark and the cheapest option: Tekpower Linear Power Supply 15V @ 2A, TP1502D, Digital Display $45

They state nowhere if the negative side is directly earth grounded. The description, for lab work and the round power cords says it should be.

 Link

I like it very much.

Christopher