Bose FreeSpace IZA 2120-HZ Service Manual page 115

100V Output Mode with 83 Ohm Loads
6. Input Sensitivity and THD+N Tests
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On the rear panel, set the 70V / 100V switch to 100V
6.1 Set the front panel Input A / Input B switch to Input A. Apply a -10dBV +/- 2dBV, 1kHz sine
wave to the input A RCA input jacks.
6.2 Verify that the output level is 120W from both channels and that the THD+N is <0.3%.
6.3 Repeat steps 6.1 and 6.2 for the Input B RCA jacks.
7. Frequency Response and Output Noise Tests
7.1 Set the front panel Input A / Input B switch to Input A. Apply a -30dBV, 1kHZ sine wave to the
input A RCA jacks. Adjust the Input A gain rear panel control to allow a 1W output level.
Reference the dB meter to this output level.
7.2 Change the input frequency to 55Hz. Verify that the output level is -3dBr +/- 1.
7.3 Change the input frequency to 18kHz. Verify that the output level is -2dBr +/- 1.
7.4 Turn off the signal generator output. Measure the noise level with a 20kHZ filter and
A-weighting. Verify that it is < -48dBV.
7.5 Repeat steps 7.1 to 7.4 for Input B.
8. Output Signal Clip Level Test
8.1 Set the front panel Input A / Input B switch to Input A.
8.2 Apply a -11.0dBV +/- 2dBV, 1kHz sine wave to the RCA input jacks.
8.3 Verify that the Output Signal / Clip LED on the front panel is lit GREEN.
8.4 Apply a -49.0dBV +/- 2dBV, 1kHz sine wave to the RCA input jacks.
8.5 Verify that the Output Signal / Clip LED on the front panel is lit RED.
8.6 Set the front panel Input A / Input B switch to Input B and repeat steps 8.2 to 8.5.
9. Aux Output Tests
9.1 Set the Input A/B switch to Input A. Apply a -12dBV, 1kHz sine wave to the input A RCA
jacks. Adjust the Input A gain rear panel control to maximum.
9.2 Verify that the output level at the Aux Output RCA jack is -3dBV +/- 1dBV.
9.3 Using a 20Hz to 20kHz audio filter, measure the THD+N level. Verify that it is < 0.1%.
TEST PROCEDURES
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