Time to play everyone's favorite game...

[Lurco]

is that some kind of antistatic (= more or less conductive) foam underneath those PCBs?

[mistahead]

Nice pickup - definately pink "digital goods" foam there...

Now I need to play with foam and my MM... hate you guys... 

[haveyouseenhim]

is that some kind of antistatic (= more or less conductive) foam underneath those PCBs?

That foam is ok to use. I checked with my meter and it doesn't conduct at all.

[Govmnt_Lacky]

is that some kind of antistatic (= more or less conductive) foam underneath those PCBs?

YES.

It is antistatic non-conductive foam.

[mistahead]

Dammit, I tested some too because of this thread hahahah.

Just for edification - is is possible to wrap those boards in insulator, then wrap in something that will sheild, just to confirm that they are "apart" enough that the parasitic noise in either "in one of them" or in wiring, not crossing over the two?

Probably a pain to confirm what is pretty unlikely anyway...

[Govmnt_Lacky]

I believe I will need to go with shielding the in/out wiring.

I was able to remove and pull the chorus board outside of the enclosure and actually somewhat close the lid back on the flanger circuit so they were as isolated as possible without desoldering something. I was still getting noise (heterodyning, whooshing, thumping...oh my!)

When I get time, I will try to replace the in/out wiring with shielded wire and report back. 

[Jdansti]

Assuming you're still getting noise during bypass, you might want to try using temporary jumpers to ground the boards' inputs to see if the noise stops. That might solve half of your problem.

[Govmnt_Lacky]

UPDATE...

I installed shielded cabling from the Input and Output jacks to the bypass switch AND from the bypass switch to the Effect Selector switch. This has helped quite a bit. There is no more noise when in bypass AND the thumping/whooshing is all but gone 

I am still having heterodyning issues really bad. I am wondering if continuing the shielded wiring from the Effect Selector switch to the In/Out of both boards will help -OR- do I need to do something to "isolate" one of the PCBs from the other? I am concerned that I will install the shielded wiring to the PCBs but the clocks will still mix due to the close proximity of the PCBs/traces.

Thoughts??

[mistahead]

Big magnet.

If EMI is causing the hetrodyning a REEAAAALLLY big magnet (hard drive or fridge salvage) being waved around between will have a therimin like effect on the EMI.

Not sure it will help but if I'm right it will be cool lol.   

[Govmnt_Lacky]

Big magnet.

If EMI is causing the hetrodyning a REEAAAALLLY big magnet (hard drive or fridge salvage) being waved around between will have a therimin like effect on the EMI.

Not sure it will help but if I'm right it will be cool lol.   

Thanks but....

I'm really only interested in getting rid of the heterodyning.

I was thinking that adding a shielded wire from the output of the Flanger would do it but then I thought about the closeness of the traces between the boards and now I am second guessing.

Ideas? Thoughts??

[mistahead]

Well believe it or not my kind of TIC post actually MIGHT give you a bit of an idea as to whether its following the wires (therefore shielding them) or just proximity bleeding EMI (therefore needing to isolate/shield the boards themselves).

Interfering with the parasitic signal that way COULD help work out which of the two is the cause... but there's probably a less fun and more accurate way to do it.

[Fender3D]

Since the circuits are similar, clock block is on the right side of the boards...
You may keep chorus PCB upside down..

Remember: power supply MUST be decoupled, add an R/C cell each board and keep GND from boards separated up to power socket