Test Procedures; 502A Array Test Procedures; 502B Bass Module Test Procedures - Bose Panaray 502A Service Manual

502A Array Test Procedures

Note: All 502A procedures involve connect-
ing test equipment to the array's input
terminals. For the XLR input pin assignment,
see Figure 16 below.
Figure 16. XLR input pin assignment
1. Phase Test Male
1.1 Remove the grille using disassembly
procedure 1.
1.2 Apply an 8V DC voltage level to the
array's input terminals. Be sure to observe
polarity.
1.3 The cones of all 5 drivers should move
outward with the application of the DC
voltage.
2. Air Leak/Rub and Tick Test
2.1 Apply an 8 Vrms, 10 Hz signal to the
array's input terminals.
2.2 Air Leak Test: Block the ports. Listen for
air leaks around the drivers and all cabinet
joints. If there is a "whooshing" noise, there
is probably an air leak in one of these loca-
tions. 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 driver 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 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 mate-
rial.

TEST PROCEDURES

41
3. Shading Network Test
3.1 Apply a 2 Vrms, 2.5 kHz signal to the
array's input terminals.
3.2 Connect a 3 Ohm, 1W resistor in series
between the positive (+) amplifier output
and the array's positive (+) input.
3.3 Measure the voltage across the resistor.
It should be approximately .49V ± 0.1 Vrms.
3.4 If the measured voltage is outside the
specified range, check the following:
(1) Make sure that the passive components
are a 3 Ohm resistor, .75 mH inductor, and
5µF capacitor.
(2) Check all driver connections against the
502A wiring diagram in Figure 10.
4. Sweep Test
4.1 Apply an 8 Vrms, 10 Hz signal to the
array's input terminals.
4.2 Sweep the oscillator slowly from 10 Hz
to 5 kHz. There should not be any buzzes
or rattles from within the array enclosure.
Redress any wire or component that buzzes.
A "whooshing" noise at around 140 Hz is
acceptable.

502B Bass Module Test Procedures

Note: All 502B procedures require connect-
ing test equipment to the bass box's input
terminals. For the XLR input pin assignment,
see Figure 16.
1. Phase Test
1.1 Insert one hand into the bottom port of
the 502B. Gently touch the dust cap or cone
of the woofer. (The woofer is located above
the port hole).
1.2 Apply a 20 Vdc level to the 502B's input
terminals. Be sure to observer polarity when
applying the DC level. The woofer cone
should move outward towards the bottom
of the bass box.