Crown Audio 1200 service manual Test 19 Intermodulation Distortion, Test 20 Clipping, Post Testing

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Micro-Tech 1200 Amplifier Service Manual

Electrical Checkout Procedures

Spec: No dangerous transients.

Initial Conditions: Controls per standard.

Procedure: From an on condition, turn off the amplifier and monitor the output noise at the time of turn off. Note: Turn off noise may increase significantly if the amplifier is cycled off and on.

TEST 19: INTERMODULATION DISTORTION

Spec at 0 dB Output: 0.01%.

Spec at –35 dB Output: 0.05%.

Initial Conditions: Controls per standard.

Procedure: Load each channel to 8 ohms. Inject a SMPTE standard IM signal (60 Hz and 7 kHz sine wave mixed at 4:1 ratio). Set the 60 Hz portion of the sine wave to 38.9 Volt RMS. Set the 7 kHz portion to 25%. With an IM analyzer measure less than 0.01% IMD. Repeat test at –35 dB (reference 38.9 Volt RMS, 60 Hz portion) and measure less than 0.05% IMD.

TEST 20: CLIPPING

Spec: No protective action during test.

Initial Conditions: Controls per standard.

Procedure: Load each channel to 8 ohms. Inject a 1 kHz sine wave at each input and drive output 6 dB into clip for 10 seconds. The amplifier should not activate any protective circuits (ODEP, Fault, or LF Protection).

POST TESTING

After completion of testing, if all tests are satisfactory, the amplifier controls should be returned to the posi- tions required by customer. If conditions are unknown or unspecified, factory settings are as follows:

Level Controls: 9 to 11 O’Clock.

Sensitivity Switch: 0.775V U.S., 1.4V International.

Stereo/Mono Switch: Stereo.

Ground Lift: Lift.

Power: Off.

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Contents MICRO-TECH-1200 Avis Table of Contents Introduction WarrantyScope Parts Information Specifications PowerVoltage Conversion Features TheoryOverview Front END OperationVoltage Amplification Grounded Bridge TopologyLast Voltage Amplifiers LVAs Voltage TranslatorsHigh Side HS Low Side LSOutput Device Emulation Protection Odep Positive Electrical Checkout Procedures Test 2 Output Bias AdjustmentTest 3 Odep Voltage Adjustment Standard Initial ConditionsTest 4 AC Power Draw Test 5 Common Mode RejectionTest 7 Phase Response Test 12 Output PowerTest 16 Signal to Noise Ratio Test 13 Reactive LoadsTest 14 Odep Limiting Test 15 LF ProtectionPost Testing Test 19 Intermodulation DistortionTest 20 Clipping Spec at 0 dB Output 0.01% Spec at -35 dB Output 0.05%Parts List Non-Module Power SupplyOutput Assembly ONE PER Channel Supplimental ItemsOutput Assembly Back Panel AssemblyChassis Front Assembly Main Chassis AssemblyParts List Non-Module Module and Schematic Information Fuse and Display Module Parts Lists Q42549-8 Output Module P10115-7 board Parts List Q42647-0 Output Module P10137-1 board Parts List Q42717-1 Output Module P10233-8 board Parts List Q42871-6 Output Module P10305-4 board Parts List Q42968-0 Output Module P10341-9 board Parts List Q43202-3 Output Module P10397-1 board Parts List Q42552A0 Main Module D6304A4/D6304B2 board Parts List Resistor NetworksSwitches ConnectorsIntegrated Circuits Mounts U1, U2Q42714-8 Main Module D 6910-0 board Parts List Dpdt Q42776-7 Main Module D 7251-8 board Parts List OpenQ42776-7 Main Module D 7251-1 board Parts List HDR, 5 PIN Q42980-5 Main Module D7911-7 board Parts List Resistors DP3T Q43035-7 Main Module D7993-5 board Parts List NPN MPS8097Jumper IC’S Q43031-6 Main Module D7993-5 board Parts List Resistor Networks Switches