Bose FreeSpace IZA 190-HZ Service Manual page 110

4. Signal to Noise Ratio Test
Note: A 20kHz filter and A-weighting must be
used for this test.
4.1 On the rear panel, apply a 1kHz, 0dBv
+/- 1dBv sine wave to the RCA input jacks.
Verify a 90W output level on the output.
Measure the signal-to-noise level at the
output connector. Verify that it is > 88dB.
Ideal is 92dB.
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1. Hi-Pot Test
THIS IS A MANDATORY TEST
CAUTION - All units that are disassembled
as part of a repair MUST be Hi-Pot tested
before being returned to the customer.
This test applies a high voltage to the AC line
cord and measures the current leakage to
the chassis and/or other metal parts on the
outside of the unit to check for potential
shock hazards.
If the unit fails Hi-Pot test, it must be
rerturned to the technician for troubleshoot-
ing and repair of the problem, after which it
must be Hi-Pot tested again to ensure that it
now passes the test.
This test requires a Hi-Pot tester with a
ground bond attachment to perform this test.
Amplifier Connections:
The Hi-Pot tester connects to the amplifier by
means of a wiring harness. The AC line cord
of the amplifier plugs into the Hi-Pot tester
AC adapter box and another lead connects
by means of an alligator clip to an exposed
metal area on the chassis for ground con-
nectivity.
TEST PROCEDURES
Hi-Pot Tester Settings:
HiPot: 1500VAC, rise time = 1 sec., dwell = 3
seconds, current limit = 5mA
1.1 Connect the AC mains cord to the back
of the amplifier under test. Plug the other
end of the AC cord into the Hi-Pot tester.
Turn on the power switch for the amplifier.
1.2 With the tester set to the above param-
eters, perform the test. If the unit fails,
remove the top cover and repair the problem.
Once the unit is repaired, repeat the Hi-Pot
and the ground bond test to ensure the unit
is safe to return to the customer.
110
2. Ground Bond Test
Note: This test only needs to be performed
if the chassis ground wire from the AC IEC
connector or AC inlet PCB to the inside of
the chassis of the amplifier has been re-
moved or disturbed as part of a repair. If it
has not, this test does not need to be per-
formed.
This test is between the ground blade on the
AC inlet or mains plug and the earth bond
point on the rear of the chassis.
Test Parameters:
10A, test voltage of <12VAC open circuit.
Dwell time = 4 seconds. Resistance must
be < 0.1 Ohms from AC earth terminal on
IEC connector in chassis, to earth bond
point on rear the chassis.
2.1 Connect the AC mains cord to the back
of the amplifier under test. Plug the other end
of the AC cord into the ground bond test box.
2.2 With the tester set to the above param-
eters, perform the test. If the unit fails,
remove the top cover and repair the problem.
Once the unit is repaired, repeat the Hi-Pot
and the ground bond test to ensure the unit
is safe to return to the customer.