
Testing, testing, 1, 2, 3...
Apply power to the unit making sure you are applying the power correctly. Check that no
device is running hot. Any sign of smoke or strange smells turn off the power immediately
and recheck the polarity of the power supply, and the direction of the ICs in their sockets and
the polarity of the electrolytic capacitors.
Assuming everything is OK so far, it is time to apply an audio input. The easiest way to test
the Overdrive module is to use a triangle wave output from a VCO. Start with the TIMBRE
pot set to its middle position, the gain pot at its lowest and the BALANCE pot to DRY. Set
the switch to OVERDRIVE. If you listen to the output signal you should hear just the triangle
wave as it would be if it were coming straight out of the VCO. Be careful to check your
listening levels as the output signal will get louder in the next section.
Now rotate the BALANCE pot and you should hear the sound becoming brighter. Now turn
up the GAIN and listen as the sound gets both louder and brighter still. Change the switch to
DISTORTION and the sound gets louder still and more harsh. There will a small click in the
audio output as the switch is moved, this is normal behaviour. Check that the GAIN pot still
has an effect on the sound with the switch in this position.
Alter the TIMBRE pot and you'll hear that this acts as a simple tone control – boosting treble
signals at its maximum level. You'll probably also notice that with a high gain setting that the
volume increases quite dramatically too as considerably more of the higher harmonics are let
through.
If all this happens, the chances are that you have a working module.
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