Adc Pot Test (7) - Lexicon MPX 110 Service Manual

Encoder Gray Scale
The following table is provided as a reference for debugging encoder problems.
Encoder
Position 1 2
Pin 1 1 0
Pin 2 1 1
Pin 3 1 1
Pin 4 1 1
Pin 5 0 0
Note: The logic levels from the encoders are only valid when the enable (pin 5) is low.

ADC POT TEST (7)

The MIX, EFFECTS LVL/BAL and ADJUST Pots are connected to integrating type ADC's (A/D Converters)
and are read digitally by the Lexichip3. The ADC Pot Test will verify that the pots and converters are
working.
While performing the ADC Pot Test, the ADC Pot under test must be varied over its entire range from fully
counter-clockwise to fully clockwise and back to fully counter-clockwise (CCW-CW-CCW).
During the rotation of the ADC Pot under test, the data generated by the ADC circuitry during the sweep will
be analyzed and confirm that the circuit is accurately reporting the data to the Lexichip3. When the (CCW-
CW-CCW) sweep has been completed successfully, the test will display a Pass, Fail or Timeout status on
the headroom (L & R Level & Clip (red) LED's).
When an ADC Pot is being tested, the ADC Pot must be swept over its entire (CCW-CW-CCW) range
within five seconds. Otherwise, after 5 seconds the headroom LED's will indicate that a Timeout Failure has
occurred.
When selected, the Front Panel LED's will read the following:
Edit Bypass
O O
MSB
Pressing the STORE button will execute the test.
When the test is executed the remaining buttons, encoders, ADC Pots and footswitches (2) are inactive,
and all Front Panel LED's will go off.
The STORE button will be active to exit the test.
MIX Pot Pass/Fail Status:
The Left Level (green) LED will be lit to indicate when the MIX Pot is being tested. The remaining LED's will
be off.
If the MIX Pot passes the test, the Left Level (green) LED will flash about 2 times per second.
If the MIX Pot fails the test, the Left Clip (red) LED will flash about 2 times per second.
3 4 5 6 7
0 1 1 0 0
0 0 0 0 1
1 1 0 0 0
1 1 1 1 1
0 0 0 0 0
Table 3.
Store Tap
l
O
LSB
8 9 10 11 12
1 1 0 0
1 1 1 0
0 0 0 0
1 0 0 0
0 0 0 0
Lexicon
13 14 15
1 1 0 0
0 0 0 1
0 1 1 1
0 0 0 0
0 0 0 0
16
1
1
1
0
0
5-11