BBE Sonic Maximizer BBE 422A - Manual (Page 15)

CALIBRATION PROCEDURE FOR THE BBE® MODEL 422A
NOTE: THIS UNIT WAS CALIBRATED AT THE FACTORY. THIS PROCEDURE IS FOR QUALIFIED SERVICE PERSONNEL ONLY.
Revision Q-50-3, August 7, 1990
Equipment Required:
Audio Signal Generator (sine wave)
Digital Voltmeter (DVM)
This procedure details the calibration of channel A. Comments [in brackets] pertain to channel B. All tests are done with a signal
level of -lOdBu (.245Vrms) except for the clip indicator check. The signal will be input into the 1/4" connector marked INPUT. The DVM
shall monitor the 1/4" connector of each corresponding channel marked OUTPUT.
Initial Settings
1) DEFINITION controls VR2 [VR
6] to minimum.
2) Turn VR1 [VR5], VR4 [VR 8] and VR3 [VR7] to their middle positions.
3) POWER switch ON and FUNCTION switch IN (process on).
4) PROCESS switch to AUTO.
PROCEDURE:
Offset Adjustment:
1) Unit should be on and the regulators should be warm to the touch.
2) With no signal present at the input (open) measure TP1 [TP2] with the DVM set to DC volts.
3) Adjust VR1 [VR5] until DVM reads O.OOVDC.
Power Supply Test:
1) With DVM set to DC volts measure the positive end of C51. It should be less than +30VDC.
2) With DVM set to DC volts measure the negative end of C52. It should be less than -30VDC.
3) With DVM set to DC volts measure pin-4 of U2. You should read -i-ISVDC (+!- 0.5VDC).
4) With DVM set to DC volts measure pin-11 of U2. You should read -15VDC (+!- 0.5VDC).
Unity Adjustment:(Note:VR2 [VR 6] to minimum)
1) Input a 5000Hz signal (@ -lOdBu) into the connector marked CHANNEL A [B] INPUT.
2) Measure the connector marked OUTPUT CHANNEL A [B] with the DVM
3) Adjust VR4 [VR
8] until the DVM reads -13.5 dBu.
4) Set generator to 500Hz (@ -lOdBu).
5) The DVM should read -10.5 (-H/-0.5dBu).
Lo-Contour Test:
1) Input a 50Hz signal (@ -lOdBu) into the connector marked CHANNEL A [B] INPUT.
2) Measure the connector marked OUTPUT CHANNEL A [B] with the DVM set to AC volts.
3) Turn the LO-CONTOUR control completely clockwise (marked "+"). The DVM should read 0dBu.(-r/- 1 .OdBu)
4) Turn the LO-CONTOUR control completely counter-clockwise (marked "-"). The DVM should read -22dBu.(+/-1 .OdBu)
5) Turn the control to the middle position (marked "0"). The DVM should read approximately -8.5dBu (+!-1 .OdBu).
Detector Check:
(Note: The DEFINITION control must be completely minimum)
1) Input a 500Hz signal @ -lOdBu into the connector marked CHANNEL A [B] INPUT.
2) With DVM measure TP1 [TP2] you should read -I-0.380VDC (+/- 0.040VDC)
3) Change source to 5000Hz (@ -lOdBu). With the DVM, measure TP1 [TP2], you should read +0.440VDC (-r/- 0.040VDC)
Manual Process Switch Test:
1) Input 5000Hz signal @ -lOdBu into the connector marked CHANNEL A [B] INPUT.
2) Measure the connector marked OUTPUT CHANNEL A [B] with the DVM set to AC volts.
3) Turn the DEFINITION control to maximum and the DVM should read -1 .OdBu (+/- 0.5dBu).
4) Switch the PROCESS switch to MANUAL.
5) With the DEFINITION control to MAXIMUM with the DVM measure TP1[TP2j. The DVM should read -I-0.340VDC (+/- 0.030VDC)
6) Return the DEFINITION control to MINIMUM.
Bypass Test:
1) Switch the FUNCTION switch OUT (bypass mode).
2) Input a 500Hz signal (@ -lOdBu) into the connector marked CHANNEL A [B] INPUT.
3) Measure the connector marked OUTPUT CHANNEL A [B] with the DVM set to AC volts.
4) The DVM should read -lOdBu (-i-/-0.5dBu).
5) Return the FUNCTION switch to the IN position (process mode).
Remote Test:
1) Insert a 1/4" phone plug into the REMOTE JACK.
2) Confirm that the front panel function switch is inoperable. (The REMOTE footswitch will override the front panel switch.)
3) Switch the remote plug. Insure that the function changes from process to bypass.
LED Test:
1) Input a 5000Hz signal (@ -lOdBu) into the connector marked CHANNEL A [B] INPUT. The green (-i-) led should light.
2) Input a 500Hz signal (@ -lOdBu) into the connector marked CHANNEL A [B] INPUT. The red (-) led should light.
3) Disconnect the signal input and the amber (0) led should light
4) With the FUNCTION switched to the IN position the corresponding green LED should be lit.
5) With the FUNCTION switched to the OUT position the corresponding amber LED should be lit.
Clip Indicator Test:
1) Input a 500Hz signal with an amplitude of -i-16dBu (4.887Vrms) into the connector marked INPUT CHANNEL A [Bj. Insure the
corresponding CLIP LED is fully lit for each channel.
RCA Connector Test:
1) Switch the FUNCTION switch OUT (bypass mode).
2) Input a 500Hz signal (@ -lOdBu) into the RCA connector marked CHANNEL A [B] INPUT.
3) Measure the RCA connector marked OUTPUT CHANNEL A [B] with the DVM set to AC volts.
4) The DVM should read -lOdBu (-r/-0.5dBu).
5) Return the FUNCTION switch to the IN position (process mode).
DC Voltage at Output Test:
1) Measure the output jacks to ground with the DVM set to DC volts the voltage must be less then lOmVDC.
Offset drift test:
1) With no signal present at the input (open) measure TP1 [TP2] with the DVM set to DC volts.
2) Insure this voltage is O.OOVDC (+/- 25mVDC)
END TEST