BBE Maxie 401 - Manual (Page 8)

Procedure:
Power Supply Test:
1. With DVM set to DC volts measure pin -4 of U2 relative to ground and the DVM should read + 12Vdc±0.5Vdc.
2. With DVM set to DC volts measure pin -11 of U2 relative to ground and the DVM should read -12Vdc ± 0.5Vdc.
3^ With DVM set to DC volts measure pin -2 and then pin -3 relative to pin -1 of the LO-Z BALANCED input. Both pins
should read approximately +24Vdc.
Unity Adjustment:
1. Set signal source for OdBu (,775Vrms) at 500Hz input to LINE IN.
2. Connect DVM (set for AC volts) to LINE OUT referenced to ground.
3. Adjust VR6 until DVM reads OdBu (unity).
4. Change source to 5000Hz. Adjust VR5 until DVM reads OdBu (unity).
Offset Adjustment:
1. Remove signal from LINE IN so no input signal exists.
2. Set DVM to DC volts and measure TP1 relative to ground.
3. Turn DEFINITION control until DVM reads -350mVdc.
4. Change source to 5000Hz. Adjust VR2 for a reading on the DVM of +300mVdc (±5mVdc). (Note: the DEFINITION
control and VR2 interact so check the readings between the two frequency settings and make the necessary
adjustments until both readings are correct.)
Gain Test:
1. Input a tOOmVrms signal at 500Hz into the Hl-Z IN connector.
2. Set DVM to AC volts and measure the LINE OUT connector.
3. You should read 4 to 5Vrms on the DVM.
Clip Adjustment:
1. Set source for + 16dBu (4.887Vrms) at 500Hz and input to LINE IN.
2. Adjust VR8 until the CLIP LED just turns on. Any lower level input should turn the LED off.
LO-Z BALANCED Connector Test:
1. Input a balanced signal at -30dBu (24.5Vrms) into the LO-Z BALANCED IN connector.
2. Measure the LO-Z BALANCED OUT connector with the DVM and adjust the GAIN control until you read the same as the
input -30dBu. Or you should have half the input on each pin, i.e. 12.25mVrms on pin -2 and pin -3 relative to pin
-1 180 degrees out of phase.
Bypass Check:
1. Input a OdBu, 500Hz signal into the LINE IN connector.
2. Connect DVM across the LINE OUT connector.
3. Push PROCESS button to the OUT position and insure DVM reads OdBu (± 0.5dBu). In bypass you should have a flat
frequency response from 10Hz to 20kHz.
LED Check:
1
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2
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3.
4.
Input a OdBu, 500Hz signal into LINE IN.
Turn the DEFINITION control completely clockwise (maximum). The GREEN (-H) LED should light.
Turn the DEFINITION control completely counterclockwise (minimum). The AMBER (0) LED should light.
Set source to 5000Hz (OdBu) and turn the DEFINITION control completely clockwise (maximum). The RED (- ) LED
should light.
Push the FUNCTION button IN, the corresponding GREEN (IN) LED should light.
Push the FUNCTION button to the OUT position and the corresponding AMBER (OUT) LED should light. These two
LEDs should never be lit at the same time.
END TEST