Category: Audio System Repair and Service
Contents of this article
- Test procedure
- How to disassemble
BOSE SA2 - SA3
TEST SET-UP
Equipment Needed:
# DC Power Supply
# Audio signal generator
# 2 - 6 Ohm, 100 Watt load resistors
# Audio input cable part number 278128
# Connector plug part number 272953-04
# DC Power Supply
# Audio signal generator
# 2 - 6 Ohm, 100 Watt load resistors
# Audio input cable part number 278128
# Connector plug part number 272953-04
DIP Switch Settings
A Up Stereo/Mono switch (up is stereo mode)
B Down Enable/Disable auto-detect of RCA audio input (up is disabled)
C Down Slave/Master switch (down is master mode)
6 Down Room Address 1st bit (MSB)
7 Down Room Address 2nd bit
8 Down Room Address 3rd bit
C Down Slave/Master switch (down is master mode)
6 Down Room Address 1st bit (MSB)
7 Down Room Address 2nd bit
8 Down Room Address 3rd bit
9 Up Room Address 4th bit (LSB)
Set up the unit under test as described below.
1. Set the DIP Switches as described above.
2. Connect the DIN connector of cable part number 278128-001 to the amplifier Bose link DIN input connector.
3. Connect the left and right RCA connectors to a signal generator.
4. Load the left and right outputs with a 6 Ohm, 100W resistor by using connector plug part number 272953-04.
5. With the unit unpowered apply a 1.6 VDC to PIN 6 of the bottom DIN connector.
Note: The microcontroller will respond by placing the unit in a special test mode. The unit will power ON (LED will turn to solid green), source channel 2 will be selected, volume level will be set to maximum and the amplifier outputs will unmute.
6. Apply AC Power.
Note: The 2.5 VDC must be applied before AC voltage is applied.
LED Status Indicator
The green LED, located next to the dip switches on the rear of the unit, indicates the operational mode of the amplifier.
LED activity
|
Mode
|
Constant
slow blinking
|
Power
off (Standby)
|
Continuously
lit
|
Power
on
|
Lit
but rapidly flickering
|
Slave
|
Blinking
Quickly
|
Receiving
commands
|
DISASSEMBLY PROCEDURES - Bose SA2
PCB Disassembly and Transformer Removal
1.1 On the rear panel, remove the phillips-head screw identified below that secures the AC power jack to the amplifier housing.
1.1 On the rear panel, remove the phillips-head screw identified below that secures the AC power jack to the amplifier housing.
1.2 Remove the six phillips-head screws indicated to remove the amplifier
housing bottom panel. Lift off the bottom panel.
Note: The transformer is secured to the amplifier housing by four of these screws.
Note: The transformer is secured to the amplifier housing by four of these screws.
1.3 Remove the four phillips-head screws that secure the IC pressure
bar to the amplifier housing. Lift off the pressure bar.
1.4 Remove the three phillips-head screws that secure the PCB assembly to the amplifier housing.
1.4 Remove the three phillips-head screws that secure the PCB assembly to the amplifier housing.
1.5 Lift the PCB assembly and transformer up and out of the
amplifier housing. Make sure that the rear panel connectors clear the housing.
1.6 Make a note of how the transformer is plugged into the PCB assembly and remove the two transformer cables from the PCB assembly jacks at J2 and J3.
1.6 Make a note of how the transformer is plugged into the PCB assembly and remove the two transformer cables from the PCB assembly jacks at J2 and J3.
DISASSEMBLY PROCEDURES - Bose SA3
PCB Disassembly and
Transformer Removal
1.1 On the rear panel, remove the phillips-head screws identified below that secures the AC power jack to the amplifier housing as identified below.
1.1 On the rear panel, remove the phillips-head screws identified below that secures the AC power jack to the amplifier housing as identified below.
1.2 Remove the four phillips-head screws indicated to remove the
bottom panel to the amplifier housing. Lift off the bottom panel.
Note: The transformer is secured to the amplifier housing by two of these screws.
Note: The transformer is secured to the amplifier housing by two of these screws.
1.3 Remove the four phillips-head screws that secure the plate clamp
to the amplifier housing. Lift off the plate clamp.
1.4 Remove the three phillips-head screws that secure the PCB assembly to the amplifier housing.
1.4 Remove the three phillips-head screws that secure the PCB assembly to the amplifier housing.
1.5 Remove the two phillips-head screws identified, these are the
remaining two screws that secure the transformer to the amplifier housing.
1.6 Lift the PCB assembly and transformer up and out of the amplifier housing. Make sure that the rear panel connectors clear the housing.
1.7 Remove the two transformer cables from the PCB assembly jacks at J2 and J3.
