Wednesday, May 1, 2013

Fixing an 80’s Tokai Z-II Overdrive Pedal with Volume Level Issues

Here’s one for the books. This pedal had been exhibiting strange behaviour where it would work fine for ages, then suddenly the volume would drop to about 50% or so. It would stay this way for a while and then jump back up to 100%. Repeat ad infinitum.

I wouldn’t really have jumped to a “dodgy jack” diagnosis, but decided to spray a little contact cleaner in there anyway, since it was cheap and easy to do so.

It didn’t fix the problem.

The next thing I decided to try was to spray some contact cleaner in the pots (after that, it was going to be a case of checking the electronic components), but they could only be accessed by opening the box.

So I removed the back cover:

Moved the insulating sheet to the side:

Lifted the board, and immediately saw the problem. You see it?

Let me show you a close-up:

Yeah, you see it now, right? The jack on the right? The one that's supposed to be in one piece? Well here’s what it looked like:

I think we can quite safely call that a “dodgy jack”.

I can hardly understand how the pedal managed to even “almost” work fine. I can see how the ground connection was fine, but the positive contact must’ve leaned against the tip of the jack plug with just enough force to make an electrical connection. Sometimes this was so weak that the volume actually dropped.

I didn’t have one the exact same, but a standard jack fitted perfectly, so in it went:

The pedal was put back together, tested, and confirmed to be working fine:

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