MOTM

I tried this tonight, with a 320 in the audible range to my 700, no
other inputs connected.  I could not hear any bleedthrough, even when I
took my 490 filter down to minimum frequency, giving silence.  I'm
guessing your problem was from one of two causes:

1) You are overtaxing your power supply.
2) You power wiring setup is exacerbating the problem.

John Loffink
jloffink@... 

The Microtonal Synthesis Web Site
http://www.microtonal-synthesis.com/

The Wavemakers Modular and Integrated Synthesizer Web Site
http://www.wavemakers-synth.com/

> 
> My MOTM-700 was working fine except that it was effecting other
> modules through the power supply.
> 
> It caused an audible glitch in other modules.  This happened whenever
a
> router
> switched from one state to the other.  This happened even if the 700
> was only connected by its power connector.  The problem was easily
> heard  by using a 320 in the audible range.  Both routers within the
700
> were
> identical in effect, and the problem seemed twice as bad when both
> routers switched at the same time.
> 
> Has anyone reported this or a similar problem??  One could easily be
> fooled into thinking that a noise heard when switching audio is
> caused by the VCA circuitry.  My guess is that there is a transient
> from the LED's (perhaps both LED's are lit briefly exceeding the
> capacity of either the 12V or 5V regulator).
> 
> C1 is a capacitor going to ground between the 5V regulator and LED's.
> The one from my kit was a 10uF 50V cap. I didn't have any 50V caps
> that would fit, and the schematic shows a 10uF 25V.  So in order to
> provide more local storage, I put in in a 47uF 25V cap.  The problem
> went away, but after a couple of minutes the 700 started behaving
> erratically, and then stopped working altogether.  The cap burned
> out.  It's now a perfect DC conductor sitting in my trash bin.
> 
> So I put in a 47uF 35V cap.  I had it running all night, and it is
> still working fine.  No more PS glitch.
> 
> I still have no idea how 5 volts destroyed a 25V cap.
> 
> 
>