Boneyard painfull but, ok with buffer

[angrykoko]

So i built a boneyard, and like a couple have reported I get the sqeal when I turn either of the gain / crunch knobs past noon (even tried dropping the hi-gain pot to 1/2 value but same issue).
Used shielded wire throughout also.

Putting my boss eq pedal in front of it fixes the problem like was reported.

So I guess I'd like to build a perm input buffer into this???  Any suggestions for a buffer?  something simple and small?  Or have I missed something else to try?

Thanks!

[murdog47]

Have you changed the R5 and C5 values as follows?
R5 100R
C5 1uf
That along with the pots cleared mine up

[angrykoko]

I didn't try that.  I read it as the 1/2 gain mod when I saw that and thought it would change the pedal into something I wasn't looking for... but, It's easy enough to try.. I think I have a 1u & 100r laying around...

[angrykoko]

Ok, tried it.. no change

I left RPD out, is that supposed to be jumpered (I didnt jumper it).

[angrykoko]

Ok, got an idea.  While testing the jumper theory with a paper clip (yeah I'm lacking some duct tape and PBR... I know)... I found that if I just put the paper clip near the input connection... or better had the 2 sides of my paper clip on either side of it... the whine stopped.  I'll re-do this bit of shielded wire and see what I get.

If that doesn't do it.. could it be something with C2 ??

[angrykoko]

No good with new input wire.  Tried it without the shielding connected also,  Repaced C2 with a new cap... still same squeal.

So... I have 2 working fixes... input buffer or hold a paper clip with my hand near the input connection at c2.

[pryde]

So did the R5=100R and C5=1uf make no difference in the squeal?

[angrykoko]

Yeah, I still squeal... actually it's like a whistle now so it changed a little.
The clipping LED's are lit also while it's whistling.
I measured all the resistors and they all read the right values.



Here's a pic of where it sits currently

[pryde]

Hmm.

Is the IC a 1044 SCPA?
It looks like your C5 cap is not polarized (not sure if that matters)
Is sheiled cable only grounded at one end?

How about trying a 50k crunch and 250k hi-gain pot as well?

My pedal is all the above and I only get "a little" whistle on high gain at full clockwise?

I also notice the volume control will effect the squeal factor. Try to make sure the pedal is at unity or slightly above. Otherwise

[juansolo]

Simple and small buffer:



Full thread here. I'll let you know if it works as I'll give it a go tonight and see if it cures mine. If so it'll be going in permanently.

[angrykoko]

Hmm.

Is the IC a 1044 SCPA?
It looks like your C5 cap is not polarized (not sure if that matters)
Is sheiled cable only grounded at one end?

How about trying a 50k crunch and 250k hi-gain pot as well?

My pedal is all the above and I only get "a little" whistle on high gain at full clockwise?

I also notice the volume control will effect the squeal factor. Try to make sure the pedal is at unity or slightly above. Otherwise

Yep, it's the SCPA version.
C5 used to be a polarized 2.2uf (that one in the pic is the 1u)
Yes, shielded wire grounded only at one end.
I dont have a lot of spare pots around, that's why I only could try dropping the high gain one down to 500K

As far as volume, It didn't seem to make much difference where it was set.

[angrykoko]

Simple and small buffer:



Full thread here. I'll let you know if it works as I'll give it a go tonight and see if it cures mine. If so it'll be going in permanently.

Awsome!  I think I may have all those parts around even.  Thank you !

[angrykoko]

So I'm curious about my paper clip deal.

The pedal has to be fully connected (guitar->pedal->amp) for this to work.
I do not have to be touching the guitar strings (grounded)
and all I do is hold a paper clip that's bent into a tight upside down "U" shape near (not touching anything) the "IN" connection solder point. 

Why would that cure the squeal & whistle?

[juansolo]

So I'm curious about my paper clip deal.

The pedal has to be fully connected (guitar->pedal->amp) for this to work.
I do not have to be touching the guitar strings (grounded)
and all I do is hold a paper clip that's bent into a tight upside down "U" shape near (not touching anything) the "IN" connection solder point. 

Why would that cure the squeal & whistle?

Grounding the input through you maybe?

[angrykoko]

So I'm curious about my paper clip deal.

The pedal has to be fully connected (guitar->pedal->amp) for this to work.
I do not have to be touching the guitar strings (grounded)
and all I do is hold a paper clip that's bent into a tight upside down "U" shape near (not touching anything) the "IN" connection solder point. 

Why would that cure the squeal & whistle?

Grounding the input through you maybe?

Oops... in better light (and with my reading glasses) I see it's not the input pad... its R1! which is right next to the input pad.

Here's what I did this time.
Connect pedal fully (guitar->pedal->amp),  clip one end of a jumper to pedals ground, take other end and touch it to R1's case... whistle gone!    Could be R4 also, they are so close together that this trick may be affecting both.  The whistle lessens the closer you get to R1 then all gone once you make contact.

My jumper is just a normal alligator clip on both ends with regular wire between type of jumper, I was not touching bare metal this time.