Alesis Andromeda A6 Service Manual page 20

3.5 Tuning Problems
3.501 Single Voice Fails Tuning
° Make sure all of the components around the ASIC with the failing voice are soldered
properly and are the correct value.
° If they are, then the ASIC for that voice may be bad. Replace it and re-test.
3.502 All Voices Fail Tuning
° One of the ASICs could be shorting the tune busses. Turn off background tuning and
check the voltage on FILT_ASIC_VCA_CAL_BUS and ASIC_TUNE_BUS on the
Analog ASIC board. The voltage should be 2V. If not, remove ASICs (or disconnect
from the bus) until you've identified which one is shorting the line.
° Check the ribbon cables going from the Analog ASIC board to the Analog Master board
and the Main board.
3.503 Voice 2 Fails Tuning or ASIC Test – Has Problem with Pre Filter Path
This is a very specific problem on the Analog ASIC PCB. R73 and R74 are swapped in the
silkscreen, so the wrong parts are stuffed on the board. We found this problem on both the
A6 sample and the separate Analog ASIC board sent by Yahorng.
Take a look at an Analog ASIC board, near R74 and R73. The "R74" silkscreen is on the left
resistor, while the "R73" silkscreen is on the right resistor. But, actually, the left resistor is
R73 and the right is R74.
So, the left resistor should be a 20K resistor. The right one should be a 0 ohm resistor. Look
around the other ASICs to see what it should look like.
Confidential Alesis Service Manual 8-31-0089-C