Moog Melodia -advice on an older unit in need of some help

Hello,

I am new to Theremin World and from what I have read, this is a wonderful resource!

I am interested in reviving a Moog Melodia that my university has had in dark storage for many years, its an early 60s model from what I can glean from a bit of research.

So, it powers up and makes sound, but I believe that it needs to be calibrated, and or perhaps repaired. I'll attempt to describe some of the "issues" it has in the hopes that some of the knowledgeable folks here might be able to advise me on a path forward.

1. Both the volume and pitch knob have no "stop" or what might be thought of as a low/high setting, they are able to be rotated on and on.

2. When the unit is on, it makes a tone, but I am not able to make it be silent.

3. I am only able to perform pitch variations about 1 1/2 in. from the antenna. This does not seem consistent with videos I've seen out there.

4. The brass plate for controlling volume does not seem to work, touch it and it raises the pitch a 1/2 step.

Thanks for any advice you all might be able to provide. I'm happy to share more details.

All my best - MC

Here is the schematic, if you do not understand what you are looking at, it would be difficult to help you. The theremin is not easy.

https://www.oldtemecula.com/theremin/melodia-npn/

Christopher

1. Both the volume and pitch knob have no "stop" or what might be thought of as a low/high setting, they are able to be rotated on and on.

The knobs are capacitors that have no stops, so this is normal.

2. When the unit is on, it makes a tone, but I am not able to make it be silent.
3. I am only able to perform pitch variations about 1 1/2 in. from the antenna. This does not seem consistent with videos I've seen out there.
4. The brass plate for controlling volume does not seem to work, touch it and it raises the pitch a 1/2 step.

These may be just a lack of proper grounding.

Here is the schematic, if you do not understand what you are looking at, it would be difficult to help you. The theremin is not easy.https://www.oldtemecula.com/theremin/melodia-npn/Christopher

Thanks for posting the schematic, I appreciate it!

MC

1. Both the volume and pitch knob have no "stop" or what might be thought of as a low/high setting, they are able to be rotated on and on.The knobs are capacitors that have no stops, so this is normal.2. When the unit is on, it makes a tone, but I am not able to make it be silent.3. I am only able to perform pitch variations about 1 1/2 in. from the antenna. This does not seem consistent with videos I've seen out there.4. The brass plate for controlling volume does not seem to work, touch it and it raises the pitch a 1/2 step. These may be just a lack of proper grounding.

Hi dewster,

Thanks for your reply and for the advice! I was also thinking it might be a grounding issue as well.

MC