dbx 3BX III, Руководство по обслуживанию

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Model 3BX III Service Manual
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ALIGNMENT PROCEDURE
1. INSTRUMENTS REQUIRED
Audio-frequency sine-wave oscillator with 50 ohm output impedance (Kron-
Hite 4200A or equivalent)
10 MHz oscilloscope capable of 2 mV/div sensitivity (Philips PM 3233 or
equivalent)
DC voltmeter capable of accurately measuring 1 mV (digital preferred,
Fluke 8060A or equivalent)
RMS-responding AC voltmeter (Fluke 8060A or equivalent)
Tone-burst generator (GenRad 1396A or equivalent)
2. INSPECTION and WARMUP
2.1 Inspect the unit to be tested and verify that all internal
interconnect cables are properly installed.
2.2 Confirm that the voltage-selector switch is in the proper position.
2.3 Connect the unit to a source of rated AC voltage, turn it on, and let
it warm up for 10 minutes.
3. POWER-SUPPLY TESTS
3.1 Verify the following power-supply conditions:
Probe location Test Condition Tolerance
3.1.1 U801, pin 3 +12 Vdc +600 mV
3.1.2 U802, pin 3 -12 Vdc +600 mV
3.1.3 Plus(+) end of C803 +18 Vdc +6 V/-1 V
3.1.4 Power indicator illuminated
If these conditions are not met, troubleshoot and correct the problem
before attempting calibration.
4. CONTROL-CIRCUITRY TESTS
4.1 Low-band rms calibration
4.1.1 Set the controls as follows:
Expansion Maximum
Impact Restoration
Minimum
Transition Level Minimum
Pre/Post Pre
Source/Tape Source
Bypass
Out (i.e., not set)
INPUTS OUTPUTS