ASM-1 VCO testing

[Aaron Harding]

Well, I'm back, with no positive results. I have checked the wiring of the
circuit 4 times now and haven't found any mistakes. Are there any key
points I should check? I took a few voltage measurements and thought I
would throw them out to see if anyone saw anything strange. I am running
+15v in on CV input one in all cases:

U1A -6.10v
U1B -13.12v
U2A 0v
U2B -5.57v
U3 -.26v
U4 +.68v
U5B -.26v
Pulse Out +6.44v
Sawtooth Out +5.56

One other thing I noticed:

My power supply puts out +14.96v and -15.06v, however, when I hook it up
to the circuit it puts out +13.94v and -14.21v. Could this indicate a
problem somewhere?

I have verified the pinout of the FET, as well as the 2N3904 trans. and
all IC's. The VCO is currently outputting a constant buzz, which does not
change with CV changes or trim pot adjustments.

Any ASM-1 guru's have any advice/suggestions?

<<aaRoN>>

On Mon, 20 Nov 2000, Tony Clark wrote:

> > Would it be possible to hook up a
> > voltage source to one of the CV inputs and hook up a 1/4" jack to the saw
> > or pulse out and  use headphones to initially verify it is working? I have
> > a control pedal which out puts 0-5v I could easily hookup to a CV in.
>
>    Yes, you can do this, but before you go plugging your headphones
> directly into the output (DON'T DO THIS!!!!!!!!), be sure to put a
> resistor in series with the output, start with something like 4.7K and
> lower the value to increase the volume.  The value will directly depend
> on the impedance of your headphones.  Some are around 600 ohms, but I've
> seen less (and more).
>
>    Tony
>
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