Allen TC-3S Volt Meter Setting

[Guest]

Greetings forum members,

I am in the process of fixing up an Allen TC-3S. One of the things that isn't quite right about it is the voltage reading on the meter that is located in the lower left corner in back (underneath the tone generator boards). A label below the meter says to set it to read 6 volts. I found a potentiometer behind and a little to the right of the meter which changes the meter reading, but the highest I can set it to is about 4 volts.

So, is this really a problem? If it is, what symptoms would it cause to have this voltage too low? And are there any suggestions as to how to fix it, if needed?

I'm at the point where I want to tune the oscillators, however if this voltage setting has any effect on the tuning I want to get that fixed first.

Thanks in advance for your help.

Best regards,
Andy Hall

[toasterDude]

Hi Andy, I just got a TC-3 last week; mine came with the additional Celeste generator as an option, so we should have nearly identical Allens.

The meter you're talking about has to do with the RMW, or Random Motion "Whind," system. It modulates the D.C. keying voltage with a white noise signal, in order to add a little random pitch variation to the oscillator outputs, as in real pipes, and also to suggest a little bit of the breathy quality of real pipes.

The voltmeter is there to indicate the relative level of the white noise signal. If you can't get it all the way to 6 volts, then according to the service manual I have that just means the Whind effect will be slightly reduced. 6 volts is the maximum setting anyway; the manual says anything higher than that makes the effect sound too exaggerated. Overall though, the RMW system will affect tuning -- for example the manual does say it can interfere with tuning by ear, just because of the slight pitch variation. So it suggests just for temporary tuning purposes you can kill the Whind temporarily by grounding its output with a clip lead.

Hope this helps-
Scott