Volume Loop Not Responding - Burns B3

Posted: 5/19/2014 3:02:47 AM

Joined: 5/19/2014

Hi thereminists,


Last time I played my burns B3 Deluxe theremin it worked perfectly, but this evening when I plugged it in again I mysteriously was unable to control the volume antenna with my hand...it makes a constant noise even when being touched. The volume knob still works to adjust the volume. Any ideas as to the problem? Your advice will be very much appreciated! Thanks so much!


Posted: 5/19/2014 7:51:46 AM

From: Colmar, France

Joined: 12/31/2007

1. variant: The link between the volume antenna and the circuit is broken. Check visually and with a multimeter if the electrical conduct between the antenna and the point where the cable joins the circuit.

2. variant: The small pot for adjusting the volume circuit which is accessible through a hole in the bottom on the volume side, is oxydated. Try to give it a minimal turn right and then back left to see if it changes something. Do NOT turn too much away from its initial position, you risk to overdrive (and thus to overheat) the transistor in the discriminator stage.

3. variant: The discriminator stage itself has a problem. The discriminator transistor (2N3906 or equivalent) is soldered directly onto the volume oscillator IC and can easily be replaced since it's a 20ct component.

Posted: 5/21/2014 1:46:51 AM

Joined: 5/19/2014

Thank you so much for your help! I will try to figure out which of those problems it's having as soon as I manage to open it up...I don't own a square screwdriver, haha. 

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