Build Your Own Clone Message Board

I realize you guys love "guts shots" and I haven't been pulling my weight around here. So without further ado, here's a little project I threw together last night, inspired by the famous Signal Tester that unfortunately is out of stock.



I use it with banana plug test leads I already had.

Nice! Looks highly functional!

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“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

At the other end of the scale, here is a minimalist way of getting the signal tester functionality, requiring only a capacitor and some hookup wire (also solder and a soldering iron, but presumably everybody here has those). It requires a slight modification of the pedal and is not portable from one pedal to another (until you are done with it and de-solder it from your pedal under test), but I offer this as a way to help out the new builder who may not have lots of spare parts lying around (as I did when I cobbled together the widget in the opening post).

(1) Get a capacitor. Best would be a non-polarized cap in the 0.01 uF (10 nF) to 1.0 uF (1000 nF) range but go lower if you have to.

For this exercise I decided to raid an expired household device circuit board. I noted that one bulky cap was marked "224" so knew there was a good chance it would be ~ 220 nF and hence appropriate. (I also set my sights on grabbing a resistor in case I needed a pull-down to avoid "pops" when using the device; I noted that both the Bass Chorus and the Green Pony, two pedals as of this writing under "discussion" in troubleshooting threads, have 100 kohm in this role so I searched for the same on the board [brown-black-yellow], and, remarkably, one was nearby. Spoiler: In the end the "pops" did not bother me so I didn't bring the resistor into play, but it is still in some of my photos.)



After encouraging my solder sucker with a few choice words, I had my parts. I have meters for measuring resistance and capacitance and the values were confirmed.





(2) The original board-stuffer trimmed the leads, of course, so next I soldered on some lengths of buss wire (can use your own discarded trimmings, just as well) to make the components a little easier to wrangle.




There seems to be a limit on the number of photos per post, so I will pick up the story here in my next installment.

(3) Next I added, to one lead of the capacitor, a length of hookup wire to serve as the "probe" part of the operation. I used solid wire so that it would have some natural stiffness, but stranded is okay too; you just would need to dress the end properly. One way would be to tin it normally; another would be to solder onto it a stiff pin of some sort.



(Yeah, I do like my heat-shrink tubing ... You can omit it, but just be careful not to make some short circuits somewhere.)

And that's basically it ... except, of course, how do you hook it into where it needs to go? Best would be to use a spare 1/4-inch jack if you have one (combined with a still-good guitar cable), or most of a retired guitar cable, but in the spirit of "I don't have anything except a capacitor I managed to scare up from somewhere" I will show you how to use your pedal's output jack for that purpose.

And I would not ask you to do something I would not myself do, so here's how it looks in my own Bass Chorus pedal.

First, the guts of the stock pedal, with the wires sorted so you can see the key wire from footswitch lug 8 to the output jack "tip" lug.



The output jack "tip" lug needs to be disconnected from footswitch lug 8. Like so:




In the next post, the signal tester gets installed and used.

(4) Now install the signal tester. The lead of the capacitor that is NOT connected to the long probe wire instead gets connected to the output jack "tip" lug. In this way, whatever point in the circuit gets tickled by the test probe wire, is the point from which a signal gets sent to the output jack (and then to your amp). The wire from footswitch lug 8 is just hanging out, hoping someday to once again be able to monopolize the output scene.



And that's it.

Here is one last photo, of me using the tester to see (hear!) just what is going on at pin 7 of the 4558 dual op amp in the Bass Chorus. You can't hear it, but I did, and it was indeed a luscious chorus-y kind of sound. The expected results were also found at pin 1 (the original signal, essentially) and at the 3207 pins 3 and 7/8 (pre- and post-BBD treatment).



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I don't consider this to be a proper substitute for a stand-alone signal tester, along the lines of what BYOC used to stock, or its variants such as the thing I illustrated earlier. But in a pinch, it can serve the same purpose.