New (broken) pedal day!

[fuzzbuzzfuzz]

Yes, apologies, very hectic here, quite a stressful month alas.

Pics to follow later in the week.

The layout however, is identical to Pepe’s pictured above.

You will see the wire leftmost soldered to the wah potentiometer (brown purple) threads down and is soldered directly to the input jack live/tip. (the remaining wires in the ream head to the circuit board and elsewhere).

[laurie]

Righto ... schematic is (allegedly) this one:
https://www.freestompboxes.org/viewtopic.php?t=25794

The pedal is a volume pedal when the wah is disengaged, so yes, it does appear that the pot connects to the output socket.

The crackling could be many things, but my money would be on the pot (even though it is new). First thing I'd do if it was on my bench would be try cleaning the pot with some Deoxit.

[fuzzbuzzfuzz]

That's right, forgot to mention its a Volume too.

Yes, when I picked it up it was scratchy, hence a pot change. I've used Contact cleaner liberally but as yet no change.

[fuzzbuzzfuzz]

Righto ... schematic is (allegedly) this one:
https://www.freestompboxes.org/viewtopic.php?t=25794

The pedal is a volume pedal when the wah is disengaged, so yes, it does appear that the pot connects to the output socket.

The crackling could be many things, but my money would be on the pot (even though it is new). First thing I'd do if it was on my bench would be try cleaning the pot with some Deoxit.

Output - yep, thanks for the correction.

[laurie]

Yes, when I picked it up it was scratchy, hence a pot change. I've used Contact cleaner liberally but as yet no change.

Roger that.

I'll have a think about it and see if anything else stands out to check in the schematic.

[fuzzbuzzfuzz]

Thank you Laurie, appreciated.

I have seen various posts here and there to indicate it can be a problem with wahs.

I also not this wah is quite microphonic, tapping the case for example. There may be a grounding issue or the inductor is on the blink.

[laurie]

I also note this wah is quite microphonic, tapping the case for example. There may be a grounding issue or the inductor is on the blink.

That's a smoking gun. Perhaps a dry solder joint - they are known for producing crackling. Can you share high-res pics, particularly of the trace side of the board?

[fuzzbuzzfuzz]

OK will do.

[fuzzbuzzfuzz]

OK it was in fact the obvious. Bought a brand new no brand ICAR alike pot, soldered in, and voila, a really fabulous vintage wah sound Now I just need a tiny nut to fix that pesky lose DC input jack and remove that awful tape. I’d happily put this up against some vintage V846 Vox wahs (that cost at least ten times this one), it’s probably as close as I will get.

[Pepe]

Well, this repair was a really annoying and ugly one.

I bought this BOSS MZ-2 as partly working in early November. The seller said that he didn't know anymore what was wrong with it. It turned out that it didn't produce a sound (or only a very low one) in SGL (single) mode. I quickly found out that the sound that came out of Output A was only the sound of Output B (it gets split if you plug a cable into B).

The first ugly thing was that the nut of the main audio jack was rusty. When I tried to get it off, the whole shaft started turning after a while. I had to file the nut off carefully, which was a lot of work - plus it produced some more scratches in the paint. The jack was broken beyond repair, so I had to stop examining the pedal until a new one arrived.

The seller or a previous owner had already swapped the Level potentiometer. It was a stereo potentiometer of the correct size, but linear and not logarithmic. Plus it had a D-shaped shaft and it was soldered in a rather clumsy way. There was a cold solder joint and once I've temporarily fixed it (and added the new jack), the pedal was alive again. But with the "wrong" (not audio) potentiometer type and the wrong axis for the knobs.

So I ordered a few 9mm stereo audio type potentiometers with knurled shaft. I had to use one of the big suppliers from the Far East, because no other shop had 100KA potentiometers with the correct design. The package arrived a few days ago and after the Christmas days I thought "let's fix this thing in 30 minutes". Ha! Ha! Ha!

The real problem was that the thin wires of the larger ribbon cable ripped off one after another. All the time something broke off on the small pcb with the potentiometers. Sometimes I noticed it only after assembling the pedal again and running into problems like no sound at all or loose contact or a missing sound channel again. At one point I desoldered the ribbon wire from the control pcb, cut a bit of all the wires off and extended them with other wires and soldered them to the board. I thought the pedal was fixed. But again some sound was missing. I opened the pedal again, only to see that the ribbon cable did now have two ripped-off wires on the main pcb.

That was when I wanted to throw that thing at the wall! Over three hours wasted and at least two of them because of an old and failing ribbon cable! Also some other connections have broken off and one solder eye of the LED cable has fallen off. I was mad at that thing - and at the previous owner who once tried to fix a pedal and made things worse.

The next day I took another new ribbon cable, soldered it to the boards, attached it with hot glue and the pedal was finally, finally fully repaired again. I then found out that it needed a new DC jack, because the original one was unreliable with switching back to the battery mode. But that was really an easy fix.

The whole pedal looks ugly inside and out. I am going to sell it for what I paid for it, plus the parts that I had to order. It works, and I think it will work for many years to come, but I want to have it out of my home.