Oscillator kill switch help (out of my league :( )

[John Lyons]

I'm getting some bleed through in the Maestro Ring here.
http://www.generalguitargadgets.com/diagrams/maestro_ring_mod_sc.gif?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a
http://pdf1.alldatasheet.com/datasheet-pdf/view/12004/ONSEMI/MC1495.html

I've made a few before and it's pretty much is the same as it always was...
Yes, I've tuned in the trimmers to the best that I feel I can.  

I'd like to ground out a connection in the oscillator/1495. Can anyone walk me through this?
I just don't know enough about what I'm looking at here.
I have a pole left on my switch that this can be dedicated to.
I've already grounded the output so the Bleedthough is in the board or wiring somehwere
even though I have used shielded wire for in/out. Crosstalk etc.

thanks

John

[caress]

try grounding the output of the oscillator rather than the output of the effect?
or try lifting some connections to the oscillator... power will most likely pop, but try lifting grounded connections - it's worked for me in the past with oscillation issues.

[John Lyons]

I did just that. (grounded the output of the Oscillator when in bypass).
Thanks for the reply though...

[Rob Strand]

What type of bleed through are talking about?
- the ring modulator sound bleeding through when the modulation pot is on linear
- oscillator ticking bleeding through

[John Lyons]

I can hear the carrier frequency faintly, even in bypass.

[Rob Strand]

Start by adding say 47ohm to 100ohm in series with each supply rail of IC4, then add say a 100uF cap to ground on each rail of IC4.  Wire these parts as close to IC4 as possible. (It's like the LFO clicking problem only the oscillator is at a higher freq.)

[John Lyons]

Thanks Rob. I was wondering if that was an issue.

[caress]

or try lifting some connections to the oscillator...

did you try that, though?   

[Rob Strand]

I woke up this morning with an idea.  It could very well be the wiring to the pitch pot, switches and possibly the carrier/osc connectors around the oscillator.   The oscillator could be coupling into the audio.  Try wrapping a ground wire around them  and/or moving them away from the audio wiring and parts.  If that works you might have to use shielded cable.


[Add:  Note if you put a spare bypass switch contact in series with the  External Carrier Jack (J3) switch contact
          it will kill the oscillator.   However the bleed through will still come through in effect mode; best to
          fix the real problem.]

[John Lyons]

or try lifting some connections to the oscillator...

did you try that, though?   

I had a spare ground point/pole on my bypass switch so I just grounded out the
oscillator when in bypass. One position LED "on" the other position grounds the osc
out.

Rob
Yes it may be the wiring even though I used sheilded in/out for the jeacks and switch
since I knew that it may be an issue. Next time I build it I'll add in your ideas. I don't
want to rip this apart again. I already have it tidy and buttoned up.

[Rob Strand]

You could try this non-destuctive test:

- Power-up effect with back of enclosure open.

- Plug a 6.5mm cable into your amplifier and turn it on and perhaps up a tad.

- Use the tip of the cable's free end to probe around the circuit. 
* Don't touch the tip onto the circuit just place it near to areas of the circuit.*

- it might be better to connect an earth between the amp and the effect

If there are parts of the circuit giving off carrier there a  good chance you could pin it down
with this method.

[caress]

or try lifting some connections to the oscillator...

did you try that, though?   

I had a spare ground point/pole on my bypass switch so I just grounded out the
oscillator when in bypass. One position LED "on" the other position grounds the osc
out.

Rob
Yes it may be the wiring even though I used sheilded in/out for the jeacks and switch
since I knew that it may be an issue. Next time I build it I'll add in your ideas. I don't
want to rip this apart again. I already have it tidy and buttoned up.

i had some issues with a negistor oscillator stage recently causing whine while bypassed and i tried the same initial fixes you did - shielded wire, tidied up my wiring, grounded the input AND output, grounded the oscillator output, etc.  still there...  eventually i wired it so that the point where the negistor connected to ground was instead connected to the cathode of my LED - this way it was connected to ground while on, but when bypassed, ground was lifted (breaking the circuit) and there was no possibility of oscillation.
i was left with a slight pop, but i figure that's better than a whine while bypassed...

[John Lyons]

I'll give that a try Rob.
I have an audio probe that I can use for this.
Thanks

John