Test Procedure
1. Attach the 10-pin end of a 10-to-16 pin cable to the 2x5 POWER header, and the other end to a
Eurorack power supply.
2. Attach one end of a 16-to-16 pin cable to the EXPANDER header, and the other end to the
EXPAND header on a QCD
3. Screw both modules into the case (optional)
4. Turn the power on
5. Tap the QCD's button twice, perhaps half a second between taps.
6. Set all QCD Div/Mult knobs to center “=”.
7. Set all QCD Expander knobs to center (all 12 knobs).
8. Set all switches to center position
9. Plug the red channel's INV OUT to an oscilloscope
If you don't have a scope, you can patch into the FM input of a VCO and use your ears to
listen to the difference in time the VCO spends being high vs. low
10. Check the duty cycle of the waveform.
What is duty cycle? Duty cycle is the time spent being high vs. the total time spent being high
or low. If the duty cycle is 50%, then the high and low times are equal, and the waveform is a
square wave.
11. Make sure the red channel Gate PW knob and the CV PW attenuator are centered
The unlabeled potentiometer on the QCD Expander is the CV PW attenuator (it's the small
knob to the left of each large Gate PW pot).
12. You should see the duty cycle be 50% (42% to 58% is ok)
13. Turn the Gate PW knob all the way to the left. Verify the duty cycle is about 7%
14. Turn the Gate PW knob all the way to the right. Verify the duty cycle is about 90%
15. Turn the Gate PW knob back to center. The duty cycle should go back to about 50%
16. Turn CV PW attenuator all the way right, then all the way left. Verify that the duty cycle does not
change.
17. Use another module to generate a DC offset voltage of about +5 volts (use a multimeter to verify
the voltage is between 4V and 6V; anything in that range is ok)
1. +5V can be generated using a SISM channel: adjust the SHIFT knob to get +5V
2. Or, a MATHS channel 2 or 3 can generate a DC voltage
3. Or, many CV sequencers can generate a DC voltage
4. Or, a PEG channel with Cycle turned off, Bi-Polar turned on, and Scale set fully CCW (all
the way down to the left) will generate about +5V on the main ENV jack
18. Patch the +5V into the red channel CV jack (left side of the QCD Expander)
19. Turn the CV PW attenuator to the center. Verify the duty cycle is still about 50%
20. Turn the CV PW attenuator all the way right. Verify the duty cycle is about 90%
21. Turn the CV PW attenuator all the way left. Verify the duty cycle is about 7%
22. Unplug the CV jack
23. Test the switch:
1. To the left, you should see a 5ms trigger
2. At center, you should see the familiar 50% duty cycle square wave
3. To the right, you should see twice and many 5ms triggers as to the left. If you turn the big
Gate PW knob to the left or right, you should see a variable shuffle pattern (every other
trigger moves closer to the previous trigger).
24. Flip the switch to the left (single trigger).
25. Plugging the +5V DC voltage (from step 14) into to Div/Mult CV jack on the main QCD
module. The Div/Mult CV jack is the unlabeled jack immediately to the right of the Div/Mult
knob on the QCD.
26. Slowly turn the Div/Mult CV attenuator knob on the QCD Expander up. As you turn it up, you
should see the frequency of the pulse wave go to x2, then x3, x4, x5, x6, x7, x8, x12 and finally
to x16
27. Slowly turn the Div/Mult CV attenuator down from noon and you should see the frequency
divide from /2, /3, /4, /5, /6, /7, /8, /16, /32
1. You may need to adjust the overall QCD timing to make it easier to recognize the slower
speeds.
28. Repeat steps 9-24 for each channel (black, blue, green).
29. Using a small Phillips-head screwdriver, adjust the LED Dimmer trimpot to set your LED
brightness preference