Bose 402 Series Manual de servicio - Página 7
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1. Phase Test
1.1 Observing polarity, apply 9 VDC to the
input connector. Refer to the figure below.
1.2 All driver cones should move outward.
Referring to figure 4, rewire any driver that
moves inward.
1+
2+
2. Crossover Test
2.1 Connect a 0.5 Ohm resistor and amplifier
to the speaker input connector as shown in
the diagram below.
Amplifier
Speaker output
-
+
2.2 Apply a 2 Vrms, 8 kHz signal to the
speaker input connector.
2.3 Measure the voltage across the 0.5 Ohm
resistor. It should be 68-90 mVrms. If the
voltage is out of range, check the crossover
components and wiring.
3. Rub and Tick Test
3.1 Apply a 9 Vrms, 10 Hz signal to the
speaker input connector.
3.2 No extraneous noises such as rubbing,
scraping or ticking should be heard.
Note: To distinguish between normal suspen-
sion noise and rubs or ticks, slightly displace
the cone of the driver with your fingers. If the
TEST PROCEDURES
Positive input
Negative input
Volt meter
Speaker
-
+
0.5 Ohm
+
-
noise can be made to go away or get worse, it
is a rub or tick and the driver should be
replaced. If the noise stays the same, it is
normal suspension noise and the driver is
fine. Suspension noises will not be heard with
program material.
4. Air Leak Test
4.1 Apply a 15 Vrms, 65 Hz signal to the
speaker input connector.
4.2 Listen for air leaks around the drivers and
cabinet seam. Reposition or replace any
gasket that is found to leak. Repairs made to
the cabinet seam should not be visible from
the exterior of the speaker.
5. Sweep Test
5.1 Apply a 9 Vrms, 10 Hz signal to the
speaker input connector.
5.2 Sweep the signal generator from 10 Hz to
500 Hz.
5.3 Apply a 500 Hz, 2 Vrms signal to the
speaker input connector.
5.4 Sweep the signal generator from 500 Hz
to 5 kHz.
5.5 Listen for buzzes, rattles or other noises.
Redress any wire that buzzes; replace any
driver that is found to be defective.
Note: A whooshing noise from the port at its
resonance frequency of approximately 90 Hz
is acceptable.
7