Preparation

Whether installing the vibe in a standard Hammond pedal box or a Dunlop Cry Baby wah pedal casing the same number of parts is used. Each part should be tested with a meter beforehand somehow to make sure the part isnÕt dead or too off spec ... for example, hfe on transistors should be checked before hand as a means of making sure the transistors work at least- gm matching can be benneficial in many instances (at least it allows uniform performance if that's what's desired).

Extra Parts List:

Since parts are mounted vertically on the top of the board the leads on parts need to be bent in accordance. After locating where each part goes on the board and getting an idea for sizes and distances you should begin shaping parts.

To warm up start with the resistors: bend one leg completely back so it runs parallel with the leg coming straight out at the other end of the part and snip the two leads together so that the shorter remaining lead measures around 1/4Ó, thereÕs no problem going a little longer. DonÕt solder anything yet. Next locate your caps and make sure you havenÕt bought caps that wonÕt fit. In general I've found that you donÕt have to fuss too much about the type of capacitor used in this circuit circuit. IÕve used ceramic caps and all other kinds of caps and I canÕt hear too much of an impact on tone. Again we snip both leads horizontally (assuming leads arenÕt axial) so that about 1/4Ó of them remains.

Now the fun part, if you notice the transistor landings on the board have a spread of about 1/4Ó - you have to spread the legs out so that 1/4Ó of spread extends between the outer legs at the height where your snip is made- again I leave around 1/4Ó or a little more length on the leads.

Soldering

Scrub the pcb board well with a soap pad under warm water and dry. Make sure all residues of grease and oxidation have been removed from the surface of the traces. They should shine. From now on avoid touching the top of the board.

Because the space is so tight the circuit has to be soldered from inside out - this means that debugging later can be a total nighmare, so attention to detail and patience along the way can save you a big hassle later. Since the transistors lie in the center of circuit blocks they are the first ones to go in.

The easiest approach to soldering parts on this vibe board is by laying a drop on only one landing-lead spot- this serves as anchor for the rest of the soldering job for that part. By not laying any solder on the other free landing spot(s) the part better chance at remaining steady and low while the solder hardens on the ÒanchoringÓ spot.

Each part landing is prepared beforehand by dabbing all terminals with a rosin flux pen (do one part at a time) I lay it down ready to be picked up and I grab a piece of solder with my loose hand and then I land my soldering gun on my targeted anchor spot. I double check that IÕm at the right place and after a few seconds (maybe 5 or 6) I land the solder between the tip and the board while pressing lightly and rolling the solder tip over the spot ... a light amount of solder is better than too much ! Now, as soon as the right amount of solder has been deposited I grab the part with a pair of tweezers and land it in position with one leg firmly planted in the molten solder and the other leg(s) standing right over the landing spot it will be soldered to next. Next the other points are soldered in and after I might touch up the anchor spot a little. A magnifying glass is a good thing to use afterwards ...

Every part should be inspected visually as soon as it has been soldered in. Look at the connections carefully from every angle if you can (before moving on make sure the part is soldered in in the right orientation when it matters); watch for blobs of solder. After all the transistors have been put in, I solder in the two trim-pots and then all resistors. After the caps and diodes have all been soldered in, and everything has been triple checked along the way we are left with the cherry.

The photocells can all be snipped leaving about 1/2Ó to 3/4Ó leads. The leads are bent down in a half moon shape so they can be adjusted later. Before you solder in the cells though, you want to grab the Radio Shack bulb and cut off the black plastic skirt on the bottom side of the bulb. I use a small flame to melt the red and white plastic wire coatings of the leads at the bulb end and pull the plastic covering back with a pair of cutters.

Then I take my soldering gun and unsolder the wires to the bulbÕs true leads. These two tiny remaining leads are spread apart and they fit exactly in position, in the center of the board, as youÕll notice. A dab of rosin flux on both the landings and the leads guarantee a solid solder connection. Then I put in the cells, adjust them so they all face the bulb directly but lie at least 1/8Ó away from it. At this point the board has been populated.

Assembly

There are two Ò+15vÓ supply connections and two ground connections to the board. Each connection point should have a separate wire running to the appropriate terminal on the 7815 voltage regulator which I normally wire directly on to the 2.1mm wall wart jack. ThereÕs an additional ground wire that goes from the audio ground connection on the board to the input jack ground ... ground on the output jack occurs through the metal chassis containing the circuit.

The Phasor Out and Chorus Out pads have wires running to the SPDT switch (or footswitch) whose switch tap feeds the true bypass footswitch. For the speed controller I wire two 1.5k resistors in series with the end leads of the pot; this sets a minimum resistance much lower than the original vibe and so allows the oscillator to run much faster for cool effects - below 1.5k the oscillator dies out. The center tap on both pots are wired together directly at the pot so only three wires need run between board and speed pot. When installing in a vibe I may use a log pot and wire it in reverse so that ohms go up when pushing down on the pedal- this way the pedal response is better adjusted to the oscillator response to variation in resistance which speeds up when turning the vibe faster. For the intensity control the electrolytic caps are soldered on the two non-ground leads directly (watch for polarity). ThatÕs it !

Calibrating and Playing

The vibe needs to be adjusted before you can play it. Previous to plugging in power make sure the 500ohm trimmer is set to full resistance so that current through the bulb driver wonÕt blow the bulb when you first turn it on- I did that a couple of times and itÕs a drag (you may want to buy a few extra bulbs just in case). Plug the power in and set the ÒintensityÓ control to ÒoffÓ and adjust both trimmers a little at a time until a faint glow appears in the bulb.

The 250k trimmer acts as an offset control and can be used to control the proportional amount of time the bulb stays shut-off during the vibeÕs cycling process. The actions of both trimmers is interactive and it may take a while to find the exact setting you like- in general the bulb should not glow too bright.

When the intensity control is full on and the oscillator is running at around 1Hz to 3Hz is when youÕll catch the light glowing at its strongest. The balance adjustments should be made here. Since the vibe seems to be used often with the intensity set at 1/2 or 2/3, where the oscillation doesnÕt appear so wobbly as it does when set at full- this is especially noticeable in chorus mode.

jc AT lynx DOT net