Bose FreeSpace IZA 2120-HZ Service Manual page 118

ZA 2120-LZ Amplifier Tests
Required Equipment:
• Audio Precision ATS-1 or equivalent
• Audio Precision AUX-0025 digital filter or equivalent
®
• Bose Volume Control User Interface (PC 041966)
• 2- 4 ohm, 250 Watt load resistors
Test Setup
• Output mode set to stereo, unless otherwise specified.
•
Load 4 ohms.
•
Auto standby switch set to "OFF"
•
Output gain trim set to max.
• All measurements for power amp needs to use an AUX-0025 Filter.
1. Output Gain Test
1.1 Place the Mono / Stereo output switch to the Stereo position.
1.2 Apply a 1kHz, 1.0dBV sine wave to the RCA input jacks.
1.3 Measure the output level. Verify that it is +26.8dBV +/- 0.5 dBV.
1.4 Place the Mono / Stereo output switch to the Mono position.
1.5 Apply a 1kHz, -5.0dBV sine wave to the RCA input jacks.
1.6 Measure the output level. Verify that it is +26.8dBV +/- 0.5 dBV.
1.7 Measure the THD+N level. Verify that it is < 0.5%.
2. Frequency Response Test
2.1 Apply a -21dBV, 1kHz sine wave to the RCA input jacks. Adjust the signal input level to
provide a 1W output across the 4 ohm loads. Reference a dB meter to this output level.
2.2 Change the input frequency to 40Hz. Measure the output level. Verify that it is -1dBr
+/- 1dBr.
2.3 Change the input frequency to 18kHz. Measure the output level. Verify that it is -1dBr
+/- 1dBr.
3. Signal to Noise Test
3.1 Apply a -1.0dbV, 1kHz sine wave to the input RCA jacks. Verify that you have a 120W output
from both channels.
3.2 Measure the signal-to-noise level, using a 20kHz filter and A-weighting. Verify that it is
> 88dBV.
TEST PROCEDURES
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