Here is the Uniwah as presented on one of the versions of the owner's manual. I think they're kinda cool. The shell is made of a thick and pretty tough "impact proof" plastic. These were made in Japan for Merson Musical Products, the parent company of Univox. It is about the same physcial size as a Crybaby, but the heel end of the treadle is taller (around 1/2" or so).

Here is a view of the bottom. The battery door is on the left side and the screw has knurled edges, so it's easy to unscrew it with your fingers.

Here is the battery door removed, which reveals another quirk of this unique wah pedal - it operates on three C batteries. The working voltage of this circuit is 4.5 volts.

When these units were new, they had this label at the 1/4" jacks. A few examples still have this sticker on them.

The treadle is held onto the shell by this shaft which is secured by a pair C-clips. I removed these so I could take off the treadle to adress something a previous owner did and to give it a thorough cleaning.

The shaft is similar to what is used on the Crybaby - one end is smooth and the other end is knurled. To remove it, it needs to be driven out in the direction shown in this picture. Was suprisingly difficult to get out, but with the help of a little bit of lubrication it finally came out.

The little piece of what I think is brass is for the push-rod actuator, which actuates the flat spring inside. More on that further down the page.

Here is the treadle as it would normally been seen. I like how the logo is molded into the rubber foot pad thingie.

By removing three screws, the circuit block is revealed. My unit had a few issues to address, which I will comment on as we go along.

Here is the component side of the PCB. Notice that it has slanted edge at the top. The footswitch is very unusual. It's a PCB mounted two-sided DPDT switch. Never seen anything like it. Even though there are 12 pins in reality it's just like a regular DPDT switch but with the ability to have double the number of connections. One side of it is used to switch off the light bulb when the pedal is in "wah wah" mode and the other side does the signal routing.

This is the copper side of the PCB. There does not appear to be any kind of conformal coating on it.

This is the arrangement used to secure the 6.8V light bulb. It's a holder that slides on/off a metal tab. It's very easy to remove and change the light bulb. Just be careful to not break the wires where they are soldered on.

Here is a side view of the flat spring assembly. It's kind of difficult to see but there is a piece of thick bent wire (approx. 3mm dia.) which limits the upward travel. At the other end of this wire is a shutter plate with a triangular cutout which controls how much light the LDR recieves from the bulb and also limits travel in the other direction.

Here is a common problem that these Uniwahs have - the inductor parts coming loose from the housing. When these become unattached it starts to sound weak/bad. To fix mine I used a healthy amount of superglue to affix it to the bottom plate. The round ferrite disc that is attached to the flat spring also commonly comes loose. The remedy was the same, superglue.

When gluing the inductor back onto the baseplate, make sure to clean up any rust, dust, etc. to ensure a good bond. Here you can also see the triangular cutout in that shutter late mentioned earlier.

Here is what it looks like with everything reassembled. The wah effect is governed by how close this piece of ferrite on the spring is to the inductor, which has a ferrite core and cup as well. These inductor assemblies are unicorns - there are no replacements so be careful not to break any of those parts!

The inductor has me a bit confused. The schematic states that it is 2.7 Henries with what I presume is 1400 turns on an unknown gage of wire. When I measured it, it ranged between about 200mH & 500-ish mH. Not sure what the deal is with that but it works good. The ferrite seems to be very slightly magnetic. The inductor cup/core has Gauss strength of approx. 1.08 and the loose ferrite piece is approx. 0.45 and the measured DC resistance was 89 ohms.

In this picture you can see the coil removed from the ferrite cup. The copper wire is very tiny, something like 48 gage. These were also glued into the cup with a very small amount of glue and these can also come loose over time.

One interesting feature of this pedal is the push-rod actuator. This is what presses down the on the end of the flat spring when the heel end of the treadle is pushed down. I cleaned and lubricated it while I was doing my restoration work.

Here you can see the push-rod actuator as it appears when the pedal is reassembled.

After I had reattached the inductor and got all of that working properly it still didn't sound right. The "wah wah" effect was weak. Although it seems uncommon for electrolytic caps to dry out in 9V (or less) circuits, I decided to check the electrolytic capacitors since they were all in important strategic positions in the circuit. Turned out that the 5uf caps measured 7.5uF! The 1uF input cap was high ESR and measured 2.85uF! After those were changed the circuit really came to life again. It was kind of a pain to do as these units are not the easiest things to work on but for me worth the effort.

Footnote: Some units had this sticker on the bottom. Not sure what the story is on that.