GGG Shin Ei Build...Too MUCH Volume?

[bluetone]

Hello,

This new GGG build (http://www.generalguitargadgets.com/pdf/ggg_secf_lo.pdf) is making me tear my hair out.

The pedal sounds fine. One problem though: The volume pot, when turned full counterclockwise, is not silent, rather extremely loud. When turned right, the volume can kill you.

It's a simple build; I've checked and rechecked it and can find no wiring errors. I'm ready to chuck the thing in the trash.

Any idea what could be causing this problem?

Thanks.

[gutsofgold]

there's an added volume boost at the end of this circuit now. If you built it post update I'd assume you could just get rid of the boost circuit.

http://www.generalguitargadgets.com/pdf/ggg_secf_sc_bst.pdf

It's based around that 2N3904 trans at the bottom.

[petemoore]

Any idea what could be causing this problem?
  The equation of amount of amplification - attenuation = output level is not to your liking.
  A volume control is an adjustable voltage divider.
  Apparently this divider has a fixed resistance between the volume control output [wiper] and ground, when the wiper is fully CCW [ATWay down] the wiper connects to the outside lug, there must be a resistor where volume pot would normally connect to Gnd.
  A number of approaches to reducing volume could be applied:
  Jumper across or remove the volume control 'minimum stop' resistor, this should allow you adjust the signal path to have 0.0 ohms resistance to Gnd. shunting the signal completely.
  Perhaps reduce the value of that resistor, a volume control that doesn't turn ATWay down helps prevent debugging.
  Pull the booster circuit from the end of the circuit, or perhaps attenuate it's input or output, or instead of pulling it, bypass it and work with the volume of it when 'in'  and 'out'.
   

[tcobretti]

There is no way that it is wired right.  If the pot is full counterclockwise, the signal is being shunted to ground.  No amount of boosting will overcome a direct connection to ground like that.

[bluetone]

I don't see any resistor on the (right) outside lug of the volume pot; it's going straight to ground. Why then would it stay so loud?

I can't get any response from the guy at GGG, so I'm in the dark

[Solidhex]

Yo

  The wiring diagram shows the pots from behind like you're looking inside the enclosure. Is that definitely the way you wired them?

--Brad

[slacker]

Lug 1 of the volume pot is wired straight to ground so if the pot is wired correctly then turning it all the way anitclockwise has to reduce the volume to zero, it can't do anything else. If yours isn't doing this then you must have a wiring error somewhere or you could possibly have a defective pot.

Have you tried replacing the pot?

Here's some things to check, which will hopefully pinpoint the problem.

Disconnect lugs 2 and 3 of the volume pot, and see if you still get any sound, if you do then you must have a short or wrongly placed component that is somehow letting the signal bypass the volume pot. If that gives you silence then reconnect lugs 2 and 3, and do the following.

Touch lug 3 of the volume pot to the DC socket ground terminal or battery negative, that should give you silence, if it doesn't then the pot is wired wrong.
If that gives you silence then touch lug 2 to the DC socket ground terminal, that should also give you silence.
Finally touch lug1 to the DC socket ground terminal. and see if that makes the pot work properly if it does then it means there's a problem with your wiring from lug1 to ground or from the board ground to the DC socket ground.

Hope this helps

[petemoore]

  Turn the pot fully CCW.
  Beep mode between wiper and Gnd. it should beep.
  That will Gnd. shunt all signal output [but I've had beannssey leaking come out], and sound like 0 volume.
  If no ground shunting, it's the ground wire to VC pot, or pot trouble.

[bluetone]

Hey, thanks guys!

I'll do all that you suggested. I have a feeling I'll pinpoint the problem this time.

[bluetone]

Well, it turned out that the pot was bad.

I think I'm learning my lesson: never reuse Alpha pots. I wouldn't mind splurging for a better quality mini-pot in the future. Any recommendations?

[petemoore]

  I guess something happened to the pot or you got a rare lemon.
  We're using Alpha pots all the time...

[bluetone]

Yeah, it's weird, I salvaged another pot from an old pedal, put it in the Shin Ei, and had the same problem: The volume cuts in and out when I jiggle the lugs. Maybe I'm getting them too hot when I solder?

Regardless, I ordered some brand new ones. Hopefully that will solve the problem once and for all.

Thanks again for all the help guys.

[tcobretti]

Maybe I'm getting them too hot when I solder?

This is quite likely.  You can definitely cook pots with the iron.