George had this wah pedal in his collection but realized one day that it didn’t work. Could the Unbrokenstring Crew help?
These pedals are common but there is very little literature available on them. That won’t stop us!
On the bottom of the unit, we find this text.
And, we find this text. Not made in PRC (Peoples Republic of China!)
The power jack is the older mono 3.5mm jack often seen on period pieces such as this.
Peering between the pedal and the base, we see the rack and pinion that runs the potentiometer, and the bypass switch.
When we open the unit, we see that the potentiometer has come loose from its mounting fork. The battery has not leaked. In fact, it’s still reading nine volts!
You can see the fork where the potentiometer mounts. All of the hardware is present and accounted-for.
We have re-mounted the control where it belongs. This requires some adjustment, as we will see later.
From the outside, we can more clearly see the rack and pinion that drives the potentiometer. Also, the bypass switch is really high. This needs to be adjusted first so that it switches only when the pedal is all the way down.
Here we see the bypass switch is mounted much lower. When the pedal is pressed downward, we hear a clean ‘click.’ This is an indication that it is adjusted correctly.
On the inside of the unit, the jam nut is tightened so that the switch stays in this position.
A little bit of petroleum jelly serves as a lubricant for the rack and pinion. The screw to the right adjusts the mesh ‘pre-load,’ keeping the teeth aligned, yet minimizing the sideways load on the shaft bearing inside the potentiometer. The gears are ‘slipped’ until the desired portion of the pot shaft rotation is in the correct place (relative to the pedal) to give us proper ‘wah’ action.
The actual ‘wah’ circuit is little more than a treble boost/cut circuit. Now that everything is together, the unit is tested with a guitar and amplifier. Now that we have confirmed that the portion of the pot rotation is OK for this unit, all the screws are tightened.
George said that he installed a new battery, so this one stays.
We are all back together and ready to return to the pedal board.
Thanks for reading all the way to the end!
CONTACT – David Latchaw EE
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