Gee.... I wonder how this works?

digi2t · January 15, 2015, 08:13:14 PM

Picked this gem up a little while ago. When was the last time you saw a triple gang pot in a wah?

Really cool fuzz wah, with a fairly big sweep, but also sounds a bit like the Tresonator (MS-20 wah) too. Exposed footswitch is the pedal bypass, treadle footswitch turns the fuzz on/off.

Like Mark's Guild TriOct, I've only ever seen two of these, this one being one of them.

aron · January 15, 2015, 08:19:24 PM

WOW, full on GOOP!

digi2t · January 15, 2015, 08:28:51 PM

Quote from: aron on January 15, 2015, 08:19:24 PM
WOW, full on GOOP!

Yup. Solid as a rock too. Probably need a Kango to whittle that stuff down.

Jdansti · January 15, 2015, 10:28:33 PM

Paging joegagan...

garcho · January 16, 2015, 01:41:16 AM

what's the goop housing made out of, adobe?

what filter needs a triple gang?

digi2t · January 16, 2015, 06:30:19 AM

Quote from: garcho on January 16, 2015, 01:41:16 AM
what's the goop housing made out of, adobe?

what filter needs a triple gang?

Piece of cardboard surrounds what feels like a solid block of epoxy. The shit is hard and glassy.

I've got mixed feelings... I really have this urge to degoop it, but I know the value of it will end up in the cellar.

R.G. · January 16, 2015, 09:26:08 AM

Here's a challenge. I figured out the circuit in a - um, heavily gooped pedal with a horsy picture on it

from only the copper side of the PCB way back when.

It's really obvious from the PCB pattern that some of those things inside the goop are a simple row of Rs, Cs and possibly diodes.

Can you (ab) use a DMM and possibly an analog resistor meter and figure out what's inside from the copper side only?

On the other hand, if you hot-chiseled off the epoxy, the epoxy job is crude enough to simply re-do with your own adobe dam to preserve the "value".

Finally, there is a rocker pedal that is a *volume* pedal that uses a quad pot that I know of.

bool · January 16, 2015, 09:33:35 AM

If The Urge is strong with you, try to hund down a non-working one.

Degooping it would really become an act of mercy then ... you could actually verify the schemo as you repair it.

"The rescue team is coming ... with a hammer!"

duck_arse · January 16, 2015, 09:49:49 AM

you could use an opamp as a hammer. is that plastic dinger that I see on the ? jack an isolated switch for the batteries?

midwayfair · January 16, 2015, 12:49:34 PM

Quote from: R.G. on January 16, 2015, 09:26:08 AM
Here's a challenge. I figured out the circuit in a - um, heavily gooped pedal with a horsy picture on it from only the copper side of the PCB way back when.

It's really obvious from the PCB pattern that some of those things inside the goop are a simple row of Rs, Cs and possibly diodes.

Can you (ab) use a DMM and possibly an analog resistor meter and figure out what's inside from the copper side only?

On the other hand, if you hot-chiseled off the epoxy, the epoxy job is crude enough to simply re-do with your own adobe dam to preserve the "value".

Finally, there is a rocker pedal that is a *volume* pedal that uses a quad pot that I know of.

Govmnt_Lacky · January 16, 2015, 01:05:09 PM

Do you have a friend at the dentist office?

X-ray that bad boy!

digi2t · January 16, 2015, 04:03:36 PM

Quote from: Govmnt_Lacky on January 16, 2015, 01:05:09 PM
Do you have a friend at the dentist office?

X-ray that bad boy!

DANG!! THAT'S AN IDEA!!! I'll have to go see my dentist and ask him if it will work.

Greg... pure genius my friend.

Gus · January 16, 2015, 05:18:03 PM

Looking at the back of the board it looks like single 8 pin opamps notice only 7, 6, 4, 3 and 2 are soldered.
Knowing that do what RG posted measure pads with an meter set to ohms
4 to ground or maybe - I see two batteries and 7 to +
Try the two common TO92 pinouts and check if it has a common wha circuit with added buffers and/or gainstages

Gus · January 17, 2015, 10:05:22 AM

I looked at the pictures some more things I noticed

The potentiometers are wired as variable resistors. The wiper and one outer lug. Can you check if linear or another taper? The potentiometers with the Yellow with Red stripe, Red and Orange wires have to lugs connected to the orange( this is if I can tell the correct wire colors on my monitor)

The ICs gain stage resistor caps look to be under the block. IC could be 741s does not look like any compensation caps to any IC pins

As RG posted the layout looks like two wire component PCB layout under the block

So two transistors and two single ICs Three potentiometers two connected with a common wire all three wired as variable resistors.

I think you can trace this without removing the block.

Voltage measurements of the circuit traces will help figure out the transistors and the circuit

Is the fuzz fixed or do you have control?

News:

Gee.... I wonder how this works?