Disassembly Procedures - Bose FreeSpace Business E4 II Series Service Manual

DISASSEMBLY PROCEDURES

Note: Refer to Figure 2 for the following
procedures.
1. Top Cover Removal
1.1 Remove the ten screws (1) that secure
the top cover (2) to the chassis (9).
1.2 Lift up on the back of the top cover and
slide it to the rear until it clears the front
edge of the chassis. Lift off the top cover.
2. LED Display PCB Removal
2.1 Perform procedure 1.
2.2 Remove the four screws (20) that secure
the LED PCB (19D) to the front panel. Lift
out the PCB.
2.3 Disconnect the ribbon cable (24) from
the LED display PCB (19D).
3. Fan Removal
3.1 Perform procedure 1.
3.2 Disconnect the 2-wire plug from the
lower power amp/power supply PCB assem-
bly (26B).
3.3 Using a 5/16" nut driver remove the four
nuts (4) that secure the fan (3) to the chas-
sis. Lift out the fan.
4. Auto Volume PCB, Wall Plate Sense PCB
and DSP/User Interface PCB Removal
Note: There are three PCBs being removed
in this procedure. The largest of the three,
mounted in the bottom of the chassis, is the
DSP/User Interface PCB. The Auto Volume
and Wall Plate Sense PCBs can be de-
tached once this procedure is performed.
4.1 Disconnect the LED harness at J510
(24) and the power/output harness at
JH501 (25) from the DSP/User Interface
PCB (19C).
4.2 Remove the six screws (18) that secure
the DSP/User Interface (19C), Wall Plate
Sense PCB (19B) and the Auto Volume PCB
(19A) to the rear panel.
4.3 Remove the two standoffs (17) that
secure the RS232 connector to the rear
panel.
4.4 Remove the two screws (20) that secure
the DSP/User Interface PCB (19C) to the
bottom of the chassis and carefully lift all of
the PCBs out of the unit.
Re-assembly Note: Be sure to replace both
screws when re-installing the DSP PCB. A
connection to chassis ground is made using
these screws.
4.5 Unplug the ribbon cables from J511 and
J512 on the DSP/User Interface PCB.
4.6 Using needle-nose pliers, compress the
ends of the standoffs that secure the DSP/
User Interface PCB to the other two boards.
5. Power Supply/Power Amp Module
Removal
Note: The E4 II Power Supply/Power Amp
PCB assembly, part number 278982-001,
is no longer available. In the event of a
power amplifier module failure, the amplifier
module used in the FreeSpace
fier must be used as a replacement. Refer
to service bulletin 278977-B2 in the back of
this manual for the repair procedure.
5.1 Perform procedure 1.
5.2 Disconnect the large ribbon cable (25)
from the DSP PCB.
5.3 Remove the three screws (20) that
secure the PCB to the chassis standoffs.
5.4 Remove the three 11/32" nuts (29) that
secure the heatsink assembly (30) to the
chassis.
5.5 Remove the four screws (18) that
secure the PCB (26A&B) to the rear panel.
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® 4400 ampli-