Dunlop JH-1 Wah Wah

Essential links for performing these mods yourself are here:

Technology of the Wah Wah Pedal
A must for anybody wanting to work on wah pedals, very lucid explanation of how the circuit works.
http://homepage.ntlworld.com/s.castledine/greenfuz/wah.html
A guideline to go about modding you Dunlop Wah pedal
http://www.stinkfoot.se/andreas/diy/mods/dunlop.htm
Another guideline, different focus
http://www.diyguitarist.com/DIYStompboxes/WahMod1.htm

Some time ago I stumbled across two Wah pedal corpses in S & G's rehearsal room. After reading all the interesting stuff at I could only resist getting started because my own Cry Baby is in tip top condition and there were some other projects going.

One the these was a JH-1 Wah



Problems with this wah was that the switch was gone, thought not a real ball breaker as we are going to true bypass it. Luckily the pot was ok, did add a lick of silicone for lubricating the 'chain" that roll the pot as well a spray of WD-40 into the pot.



a) TRUE BYPASS MOD: in the stock setup the effect board remains connected to the input even in bypass mode. This cause the board to load the signal which in its turn result in quite serious treble loss. On my solid state amp by back in the days, I used to leave the wah always engaged as tone control. Dunlop did include a buffer circuit to fight this, but still.
With the newly installed DPDT (2 separate poles) the bypass switches directly jack to jack. No treble loss.
b) INPUT BUFFER REMOVAL: with true bypass installed, the buffer section can be removed as it serves no function. It will still load the (and thus affect) the signal if not removed, so out it goes. We have to take a new connection to the input and ground for the switch. Grey = input; Brown = ground
c) GAIN MOD: 68k resistor replaced with lower value 56k for more gain
d) VOCAL MOD: 33k resistor in series with inductor is replaced with 56k for more vocal quality 'woah' sound.
e) NOISE REDUCTION: replace the two electrolytes by new ones. These are bound to dry out after some time and this wah has had 14 years already. Probably not critical, but tend to do this with all electrolytes older than 10 years. It always helps to fight the noise.




Buffer removed, all mods done -- you can see the mod sheet tucked away under the pcb, bottom left



One down! Here's a test drive