502C Controller Test Procedures - Bose Panaray 502A Service Manual

1.3 If the woofer cone deflects inward,
check all wiring.
2. Woofer Air Leak/Rub and Tick Test
2.1 Apply a 20 Vrms, 10 Hz signal to the
502B's input terminals.
2.2 Air Leak Test: Block the ports. Listen for
air leaks around the cabinet. If there is a
hissing or "whooshing" noise, there is prob-
ably an air leak. Repair any air leaks as
required.
2.3 Rub and Tick Test: No extraneous
noises such as rubbing, scraping, or ticking
should be heard. To distinguish between
normal suspension noise and rubs or ticks,
displace the cone of the woofer slightly with
your fingers. If the noise can be made to go
away or get worse, it is a rub or a tick, and
the woofer 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 mate-
rial.
3. Sweep Test
3.1 Apply a 20 Vrms, 10 Hz signal to the
502B bass module input terminals.
3.2 Sweep the oscillator slowly from 10 Hz to
300 Hz. There should not be any loud,
extraneous sounds. If there are any loud
buzzes or distortion, the woofer may be
defective.
Note: A "whooshing" noise from the port
around 55 Hz and 105 Hz is acceptable.
There should not be any buzzes or rattles
from within the 502B enclosure. Redress any
wire or component that buzzes or rattles.
TEST PROCEDURES

502C Controller Test Procedures

42
Test Setup
Input Connections: Connect an audio
signal generator to the positive (+) and
negative (-) input terminals for Channels 1
or 2. These procedures assume that the
person performing these tests is using test
equipment with unbalanced inputs and
outputs. Refer to Figure 17 for connection
information).
Output Connections: Connect test equip-
ment to the positive (+) and negative (-)
output terminals for Channels 1 or 2 (low
and high frequency outputs).
All tests should be performed for both
channels.
All test equipment must be isolated from
ground (floated).
Some settings on the controller may need
to be changed for the various procedures.
These settings will be indicated throughout
the test procedures. Refer to Figure 18 for
a diagram of the controller's back panel.
The controls on the back panel should be
set as follows (unless otherwise specified):
• Mode switch should be set at 2 (Bi-Amp)
• Output mode switch should be set at
normal
• Input switches should be set at +4 dB
• Low frequency level potentiometer should
be set at +3 dB
1. Clipping Headroom Test
1.1 Apply a 4.73 Vrms, 600 Hz signal to the
input terminals.
1.2 Distortion (at an output voltage of 6.29
Vrms) should measure -1% (measure
across the High Frequency outputs).