Friday, 28 April 2017

Carlsbro Suzz / Wah-Wah teardown / minor repair

I recently stumbled on an old Carlsbro suzz / wah-wah guitar effect pedal that I was given at some point in the 1990s. A quick google revealed it doesn't appear to be a particularly common pedal but interestingly it appears the two halves were available as individual pedals and there is a touch more information about them. Anyway, here is my two-in-one.

A hand written date inside the case suggests the pedal was made around the 7th March, 1980.

A quick test revealed that it didn't work but it was very straight forward to take apart. There are three screws on either side panel and a few on the battery cover on the bottom. The pedal is held on with two more but once they are all out the panel with the switches slides out fairly easily and the two separate PCBs are visible.

The first problem was obvious. A large section of the ground track was completely burnt out, presumably from an incorrect voltage being applied at some point. This is probably why I ended up with it in the first place.

The pedal worked after soldering in a new wire but it was very noisy and crackly, especially the potentiometers. Since the boards were already out, I ordered new pots and at the same time replaced the electrolytic capacitors just in case they had gone off. The pots were as close a match as I could find but still weren't close enough. The length of the thread was much shorter on the new ones and this meant that they didn't fit in the case correctly. Luckily, the threaded part is just held on with 4 pressed down tabs so I could salvage the thread from the old ones and transplant them on to the new ones.

With the caps and the potentiometers replaced, the pedal seems to work I'm guessing as intended. It isn't the type of pedal you'd choose to use over modern alternatives but it certainly has a distinctive look. A nice touch with an old bit of kit like this are the hand written signatures on the PCB, presumably of the people who populated the board. 'Sue' was written on the Suzz board while 'Alison' was written on the wah-wah board.

In terms of the circuitry there are various schematics for the suzz pedal available online but if anyone is interested in this particular pedal, which appears to differ a bit from the schematics online, I've overlaid the traces on top of the layout so it should be easy enough to see what is going on.

The wah-wah side:
The suzz side:

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