Test Procedures; Iza 250-Lz Amplifier (Low-Z Master Unit) - Bose FreeSpace IZA 190-HZ Service Manual

IZA 250-LZ Amplifier (Low-Z Master Unit)

Items required:
Audio Precision ATS-1 or similar
Audio Precision AUX-0025 filter
4 Ohm, 100 Watt load resistor
Control settings:
• Set the Bass and Treble control to the
12:00 o'clock position, unless otherwise
specified.
•
Set the EQ to FLAT, unless otherwise
specified.
• Set the Output gain trim to max and the
master volume control to max, unless
otherwise specified.
•
Set the Input gain trim to max, unless
otherwise specified.
• DIP switch settings:
• PAGE/MIC NORMAL - BYPASS
MASTER: set to PAGE/MIC NORMAL
•
OUTPUT MONO - OUTPUT STEREO:
set to OUTPUT STEREO
• FRONT MIC MIX - FRNT MIC DUCK:
set to FRONT MIC MIX
•
AUX OUT EQ - AUX OUT FLAT:
set to AUX OUT EQ
•
Connect the 4 ohm load to the output.
Note: All power amplifier measurements
require the Audio Precision AUX-0025 filter to
ensure correct readings.
1. Input Sensitivity Test
1.1 On the rear panel, apply a 1kHz, -10dBv
+/- 2dBv sine wave to the Input A and Input B
RCA input jacks. Verify a 50W output level on
outputs 1 and 2.
1.2 On the rear panel, apply a 1kHz, -58dBv
+/- 3dBv sine wave to the + and - inputs of
the Page Input jack. Verify a 50W output level
on outputs 1 and 2.
1.3 On the front panel, apply a 1kHz, -58dBv
+/- 3dBv sine wave to the + and - inputs of
the Mic/Line Input jack. Verify a 50W output
level on outputs 1 and 2.

TEST PROCEDURES

99
1.4 On the front panel, apply a 1kHz, -5dBv
+/- 2dBv sine wave to the + and - inputs of
the Aux Input jack. Verify a 50W output level
on outputs 1 and 2.
2. THD+N Test
2.1 On the rear panel, apply a 1kHz, -10dBv
+/- 2dBv sine wave to the Input A and Input B
RCA input jacks. Verify a 50W output level on
outputs 1 and 2. Measure the THD+N level
at outputs 1 and 2. Verify that the THD+N
level is < 0.8%. Optimum level is 0.3%.
2.2 On the rear panel, set the Page input
gain to 12 o'clock. Apply a 1kHz, -62dBv
+/- 3dBv sine wave to the + and - inputs of
the Page Input jack. Adjust the input level
until you have a 50W output level on outputs
1 and 2. Measure the THD+N level at out-
puts 1 and 2. Verify that the THD+N level is
< 0.8%. Optimum level is 0.3%.
2.3 On the front panel, set the Mic/Line input
gain control to 12 o'clock. Apply a 1kHz,
-62dBv +/- 3dBv sine wave to the + and -
inputs of the Mic/Line Input jack. Adjust the
input level until you have a 50W output level
on outputs 1 and 2. Measure the THD+N
level at outputs 1 and 2. Verify that the
THD+N level is < 0.8%. Optimum level is
0.3%.
2.4 On the front panel, apply a 1kHz, -5dBv
+/- 2dBv sine wave to the + and - inputs of
the Aux Input jack. Verify a 50W output level
on outputs 1 and 2. Measure the THD+N
level at outputs 1 and 2. Verify that the
THD+N level is < 0.8%. Optimum level is
0.3%.