Build Your Own Clone Message Board

I accidentally installed the B25k and didn't realize it. I am trying to figure out if it would be worth desoldering everything to install the appropriate pot.

What differences can I expect?

The B25K has a large "deadband" in the middle of the sweep where the tone control has almost no audible effect. The effective portions of the sweep are at either end. The B10K reduces the size of that deadband considerably. Personally, I prefer a B2K, where the deadband is pretty much gone. I'd recommend trying it and seeing what you think. Some people don't use the Tone control much and tend to "set and forget" it. If it bugs you, you can always change it later.

Thanks for the quick reply, duhvoodooman!

That's an interesting note on the b2k. I might try it later on, but I already installed the 10k. And after doing so I was so so happy to go plug it in and see what it sounds like but lo and behold... whenever either foot switch is activated I get no volume!

I modded it as a bass pedal and, although I made a mistake and resoldered once or twice along the way, it went pretty smoothly and I was pretty gentle on the soldering. I attached a pic just in case you or anyone else has an eye for it.

Thanks so much for your help!

Behold, the picture I mentioned earlier...

Errm ... you know you have no IC in the 8pin socket ?

Ahh, yes. That seems pretty obvious this morning.

I couldn't find my MOSFET chip so I used one of the others and encountered the same problem: bass signal went through clean just fine, minuscule amount of signal when the boost was engaged, and none when the od was engaged.

I've read that the chips are interchangeable. Maybe not for this build?

They're interchangeable, period.

Just so that I'm clear on the situation--was the pedal fully functional before you switched the tone pot?

No, I had not yet tested it at that point. I figured that it wasn't that difficult to replace and I wanted to build it according to the specs in the manual. After replacing it I connected the foot switches and tested it out but got low (no) output from the boost switch (I had to crank that knob all the way up to even hear it) and no sig from the OD (although I did get some low volume humming). Then I updated this thread with a photo of the PCB.

This morning I checked and Tark pointed out that I had no IC (woops!). I couldn't find the MOSFET chip so I installed one of the ones included in the regular OD2 kit and then tested it with the same results.

Do you have a multimeter available to be able to measure circuit continuity, resistance, voltage, etc?

Do the LED's light up when their respective footswitches are engaged?

Would be helpful if you posted a photo of the solder side of the PCB.

Unfortunately, I do not have a multimeter. I'm at work right now and won't be able to post a picture of the solder side for a few hours. The led's do light up.

Check the 'dumb' stuff first - input and output jacks in the right sockets?

Is the op-amp chip in the right way round and is it a new and probably working chip?

If the LEDs light brightly then the battery is probably OK, if they are dim ....

I took it to a guy at a local guitar shop and he had a look at it. He resoldered the i/o jacks and then plugged it into an oscilloscope and basically said "Yeah it's fine now." I tried it out when I got home and it still has the same issues:bypass is fine, both footswitches do nothing.

Here are some pictures of the solder side, if you need more or better photos then I'd be more than happy to repost. Again, thanks for your help!

Damn, that's annoying, I hope you didn't pay the guy anything.

Just eyeballed your build against my MOSFET OD2. You have fitted the back to back MOSFETS around IC1a, but no diodes (either LED or 1N4148s) which would leave you with only a choice of no clipping components or MOSFETs on the toggle switch rather than - diodes - no clipping components - MOSFETs. However that should not stop the pedal from working.

The fact that you get no signal for any 'active' setting of the foot switches suggests that the signal is getting lost quite early on after the input jack (or possibly just before the output jack). The OD circuit and the Boost circuit are independent circuits with a bypass switch around each of them. With the OD bypassed it is still possible to switch the Boost to active and the Boost is a very simple circuit so there is not much in it to go wrong. If you cannot get signal through the pedal with just the Boost active there aren't too many places it can get lost.

One possibility, given that you have used MOSFETs (you did fit the BS170s throughput didn't you - no MPSA18s have snuck in there?) is that you have blown one or more BS170 MOSFETs due to static. Although if you cannot get the boost to work on its own then the boost MOSFET would have to be one of them.

Signal tracing with an audio probe from the input jack onwards is the way to go next.