Guitar effects pedal: Build Your Own | Build Your Own Pedal: Main Assembly and wiring

PCB assembly

-First find the three PCB pads aligned north-south with no tracks attached, about halfway across the board. These are drilling guides for the switch terminal ports, and must be drilled out with the 3mm drill. With this done, start to insert components.
- The upright electrolytic caps have a ‘-’ symbol on the casing, and this should be oriented away from the ‘+’ symbol on the board.
- To secure an inserted component, bend its wires back along the tracks that lead to its pads, then cut them short, not more than 2mm.
- Solder the cut terminals every few components to avoid ‘hot and cold’running of the iron. There are no links in this board, so your finished board should look like this.

Special note: there’s a resistor that’s fitted from the Drive pot minimum terminal to its case, which we’ll describe in the next section, so don’t worry about having one left over when you’ve finished the board – it’s needed elsewhere.

Main assembly

When the case paint is hard, and you’ve applied any decorative artwork or lettering, fit the LED, pots, jacks, and switches.
- Shorten the LED wires to about 10cm, preserving or increasing the length difference (the long wire is the positive in the wiring diagram) then bend them 90˚ as in the picture.
Cut two pieces (one black about 12cm, one red about 9cm) from the wire supplied in the kit, making sure there’s enough black wire to lie easily between the LED negative and the footswitch – it has the longest run of all the wires and it’s better to be generous than have to fit a longer piece later.
- Strip and tin the ends, and solder them to the positive and negative terminals of the LED, red denoting positive. Having soldered the wires to the LED, slip 2cm of black sleeving down each wire and over the LED terminals.
- Pass the plastic bush through the front of the case (it should be an easy push-fit), press the LED into it from the rear, and slip the plastic ring down the wires and over the end of the bush to support it. Your final assembly should look like this.
- With the LED in place, fit the jacks and pots, having cropped the pot shafts to 9mm, and the small toggle switch. The pots have a small locating lug that should be removed using the blunt-nosed pliers, and are fitted with the serrated washer inside the case.
- Orient the terminals to five o’clock. Test-fit the control knobs and adjust the pots so that the flat on the shaft at minimum (full ACW) rotation allows the knob to point at seven o’clock with its grub screw tightened (this sounds more complicated than it is). Then, holding the body of the pots from inside, tighten their fixing nuts using pliers or an adjustable spanner. You might find it makes an easier wiring job if you bend the Tone pot terminals slightly upwards to be clear of the toggle switch.
- Fit the small toggle switch and the jacks. The toggle switch terminals align vertically as shown, with one nut inside to set the height, and the serrated washer on top of it but inside the case. The flat washer and the fixing nut fit outside. The contoured plastic dress-washers for the jacks fit outside the case, and two (only) of the spacers inside.
- Now cut two of the self-adhesive feet in half using a hobby knife (take care: they’re quite tough), and press a half-foot onto the rear of each pot to provide support for the PCB. Lastly, fit the footswitch in line with the jacks, with its inner (hex) nut about halfway up the thread. The ring nut can be tightened with pliers held flat to the pedal casing, holding the box against the torque.

Pre-wiring

- First fit R18 (the 1KOhm resistor spare from the board assembly) between the minimum end of the Drive pot and its case and solder the ends as shown in the kit wiring diagram. Do the same with a long offcut wire between the minimum end of the Level pot and its case.
- Now connect the earth circuit using black wire, using the wiring guide in the kit with our picture as a reference, and the signal circuit using red wire – you can make enough slack to ease the final wiring of the board, using the wiring diagram as a guide, as it’s full-scale. Don’t solder wires to the toggle switch yet: cut and strip the ends of two 5cm pieces of whichever colour you’ve got most of, pass them through holes 9 and 10 on the board, and solder them to the pads.

Final wiring

- Strip and tin 5mm at the free ends of the wires and, using the numbers on the wiring guide to match those on the PCB, pass them through the corresponding PCB holes and solder them. Note pad 8 has no connection.
- Fit the board into the pedal, with the tinned ends of the switch terminals showing through the three small ports in the board. Dress the wires to clear any obstacles. Press lightly on the board and tack-solder the wires you pre-fitted to PCB terminals 9 and 10 to them. This completes the wiring. All that remains is to fit a fresh PP3 battery.

Ready to go

Let’s test your Blue Tube.- First, with all controls zeroed, insert a jack into the In/On socket. Click the footswitch, and the LED should switch on or off. Now connect your guitar to the In/On jack, and the Out jack to your amp. With all pedal controls at mid-point and a low amp volume setting, play a few notes, clicking the footswitch. Bypass (no LED) should give normal level and tone. Effect should light the LED and give a big level and tone increase.
- With the toggle switch in the ‘off’ position, adjust the Drive and Level controls to get the sound you want. For more distortion increase Drive and back off Level, for clean boost do the opposite, and you should find that Blue Tube creates quite subtle mixes of the two. Tone allows you to make the boost treble, middle, or bass dominant, fully clockwise for maximum treble. Throwing the selector switch increases and hardens the distortion, but you can use the Drive control to back it off, and with altered control settings it can sound like the switch is in the off position (it’s intended to emulate the Tube Bender sound, and the labelling in our picture is provisional).
- Finally, the type of guitar you use will greatly influence the control settings. A single-coil pickup will typically require higher Drive settings to get obvious distortion than a humbucker – settings above 6/10 for the first, probably less than 4/10 for the last. The selector switch will be useful here, too.

Guitar effects pedal: Build your own picture instructions