Bose 802 E Service Manual

							1        PROPRIETARY INFORMATION
THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION OF
BOSE
® CORPORATION WHICH IS BEING FURNISHED ONLY FOR THE
PURPOSE  OF SERVICING THE IDENTIFIED BOSE PRODUCT BY AN
AUTHORIZED BOSE SERVICE CENTER OR OWNER OF THE BOSE
PRODUCT, AND SHALL NOT BE REPRODUCED OR USED FOR ANY
OTHER PURPOSE.
Contents
Safety Information ............................................................................................................................. 2
Electrostatic Discharge Sensitive (ESDS) Device Handling .......................................................... 3
Theory of Operation ...................................................................................................................... 5-8
Figure 1. Block Diagram ....................................................................................................................8
Disassembly/Assembly Procedures .......................................................................................... 9-11
Test Setup Procedure ..................................................................................................................... 12
402
® Test Procedures ................................................................................................................ 13-15
802® Test Procedures ................................................................................................................ 16-18
Part List Notes ................................................................................................................................. 19
Figure 2. 402, 802 II Original Version Exploded View .....................................................................20
Figure 3. 402, 802 II Current Version Exploded View ......................................................................20
Main Part List ............................................................................................................................. 21-22
402 Electrical Part List .............................................................................................................. 23-28
802 

 Electrical Part List ..........................................................................................................29-35
402 

 Electrical Part List ..........................................................................................................36-42
802 


 Electrical Part List ......................................................................................................... 43-48
402 and 802 

 Electrical Part List ............................................................................................ 49-50
Packaging Part List ......................................................................................................................... 51
Figure 4. Packaging Exploded View ................................................................................................51
Frequency Response Curves ................................................................................................... 52-64 
						

							2             1. Parts that have special safety characteristics are identified by the         symbol on
                schematics or by special notes on the parts list. Use only replacement par ts that
            have critical characteristics recommended by the manufacturer.
            2. Make leakage current or resistance measurements to determine that exposed
                parts are acceptably insulated from the supply circuit before returning the unit
            to the customer. Refer  to Par agraph 84 of UL 1270. Use the following checks to
perform these measurements:
A. Leakage Current Hot Check-With the unit completely reassembled, plug
the AC line cord directly into a 120V AC outlet. (Do not use an isolation
transformer during this test.) Use a leakage current tester or a metering
system that complies with American National Standards Institute (ANSI)
C101.1 “Leakage Current for Appliances” and Underwriters Laboratories
(UL) 1492 (71). With the unit AC switch first in the ON position, then in the
OFF position, measure from a known earth ground (metal water pipe,
conduit, etc.) to all exposed metal parts of the unit (antennas, handle bracket,
metal cabinet, screwheads, metallic overlays, control shafts, etc.), especially
any exposed metal parts that offer an electrical return path to the chassis.
Any current measured must not exceed 0.5 milliamp. Reverse the unit power
cord plug in the outlet and repeat test. ANY MEASUREMENTS NOT WITHIN
THE LIMITS SPECIFIED HEREIN INDICATE A POTENTIAL SHOCK HAZ-
             ARD THAT MUST BE ELIMINATED BEFORE RETURNING THE UNIT TO
            THE CUSTOMER.
B. Insulation Resistance Test Cold Check-(1) Unplug the power supply and
connect a jumper wire between the two prongs of the plug. (2) Turn on the
                power switch of the unit. (3) Measure the resistance with an ohmmeter be-
tween the jumpered AC plug and each exposed metallic cabinet part on the
            unit. When the exposed metallic part has a return path to the chassis, the
           reading should be between 1 and 5.2 Megohms. When there is no return path
                to the chassis, the reading must be “infinite”. If it is not within the limits specified,
                there is the possibility of a shock hazard, and the unit must be repaired and re-
                checked before it is returned to the customer.
SAFETY  INFORMATION 
						

							3
ELECTROSTATIC DISCHARGE SENSITIVE (ESDS)
This unit contains ESDS devices. We recommend the following precautions when repairing,
replacing, or transporting ESDS devices:
• Perform work at an electrically grounded work station.
• Wear wrist straps that connect to the station or heel straps that connect to conductive floor
mats.
• Avoid touching the leads or contacts of ESDS devices or PC boards even if properly
grounded. Handle boards by the edges only.
• Transport or store ESDS devices in ESD protective bags, bins, or totes. Do not insert unpro-
tected devices into materials such as plastic, polystyrene foam, clear plastic bags, bubble wrap
or plastic trays.
DEVICE HANDLING 
						

							4 Dimensions:1.63" H x 19.0" W x 10" D (4.14 x 48.3 x 25.4 cm)
Weight:5.5 lbs. (2.5 kg.)
Chassis material:16 gauge steel with painted/zinc coated finish
Cover plate material:Brushed aluminum, painted
Input Connections:Balanced  XLR
Output Connections:Balanced high frequency and low frequency XLR
 Input Impedance:Balanced input, -10 dB level: 14 k 

Balanced input, +4 dB level: 6 k 

Unbalanced input (+ input used), -10 dB level: 12 k 

Unbalanced input (+ input used), +4 dB level: 4 k 

Output Impedance:100 
 nominal
Input Level:-10 dB or +4 dB, selectable
Output Level:8.0 Vrms max. @ 1 kHz into 10 k 
load
Low Frequency (LF)
Output Mode:Sum or normal
LF Output Level: -18 dB to +3 dB, variable
Crossover Frequency:140 Hz (Bi-amp mode), Roll-off slope: -18 dB/oct.
Total harmonic distortion:
802:Midrange distortion of HF output: 
< 0.2 % at  5.8 V, 700 Hz
402: Midrange distortion of HF output: 
< 0.2% at  1.4 V, 850 Hz
402, 802: Low frequency distortion of LF output: 
< 0.1 % at 160 mV, 80 Hz
Output Noise:Bi-amp mode, HF outputs: 
< 90µV
Bi-amp mode, LF outputs: 
<  40µV
Passive mode: 
< 90µV
Offset:All channels: 
< 15 mV
Power Requirements:120 VAC, 50/60 Hz, 12 Watts (US/Can.)
230 VAC, 50/60 Hz, 12 Watts (Eur.)
100 VAC, 50/60 Hz, 12 Watts (Japan)
240 VAC, 50/60 Hz, 12 Watts (Aus./UK)
SPECIFICATIONS 
						

							5
THEORY OF OPERATION
This discussion is an electrical overview of the 402® and 802® controllers. Equalization curves
are referenced and are located in the back of this manual. Additionally, the block diagram and
schematic diagrams should be referenced as required.
1. Differential Input Stage
The input stage features protection against RFI (radio frequency interference), ESD (electro-
static discharge), and overvoltage. Referring to the channel 1 circuit,  R2/C1, R1/C120, R3/C2,
and R9, R10/C7 provide low pass filtering to reduce the possibility of RFI. Diodes D1-D4, D25,
and D26 provide input clamping to protect against overvoltage and ESD.
Op-amp U1 amplifies the difference between the + and - input pins, and converts it to a single
ended signal that drives the equalizers. Gain switch S3  selects between two gains, a high gain
setting for -10 dB sources and a low gain setting for +4 dB sources.
2. Equalizer for High Frequency Outputs
Op-amps U1, U2 and U3 constitute the principal equalization for the high frequency output.
Each stage makes a contribution to the total low or high frequency contouring required by the
loudspeaker. Op-amp U4 (pins 12, 13 and 14) implements a high pass filter suitable for the Full
Range mode, while op-amp U4 (pins 8, 9, and 10) is selected for a high pass filter with a higher
corner frequency for use in the Bi-amp mode. The circuitry is duplicated for both channels. See
the high frequency equalization curves for more information about the stage by stage response
of the equalizer.
3. Output mode switch, Low frequency level control, and Normal/sum mode stage
Output mode switch S2 (on the rear panel) controls op-amp summing amplifier U6 (pins 5, 6,
and 7). In the normal mode, the stage is not used, and the channel 1 and channel 2 low fre-
quency outputs pass independent, 2-channel bass to 2 bass cabinets. In the sum mode, chan-
nels 1 and 2 are combined, and this "mono" bass signal appears at the channel 1 low fre-
quency output only. Potentiometer R126  (on the rear panel), Low Frequency Level, provides for
adjustment of the signal sent into the low frequency equalizer.
4. Equalizer for Low Frequency Outputs
After the normal/sum stage, there is op-amp stage U7 (pins 12, 13, and 14) and op-amp equal-
izer stages U7 (pins 8, 9, and 10), U8 (pins 12, 13, and 14), and U8 (pins 8, 9, and 10).  The
equalizer provides high pass, low pass, and contouring equalization. See the low frequency
equalization curves for more information about the stage by stage response of the equalizer.
5. Mode switch
Rotary switch S1 is located on the rear panel. It selects the four operating modes for the con-
trollers. Currently, position 3 (NC) is not used. 
						

							6 6. Output stage
NOTE: The components mentioned in this paragraph are for the high frequency output only.
The output stage is compatible with balanced signal transmission systems. Inver ting op-amp
stage U9 (pins 1, 2, and 3)  provides the output signal. Diodes D9, D10, D29 and D30 provide
output clamping to protect against overvoltage and ESD. Relays K1 and K2 clamp the outputs
to ground to protect against power on/off transients. When the relay is de-energized, as when
the AC power is off, the outputs are clamped.  About 1.2 seconds after the power is turned on,
the relay is energized by transistor Q1 and allows audio to pass through the controller. When
the power is turned off, a fast acting detector de-energizes the relays to protect against power
off transients.
NOTE: At the controller outputs, only the positive (+) output pin is driven. The negative (-)
output pin is connected to signal ground through a series impedance identical to the positive (+)
pin. When used to drive a balanced input, the controller output provides equal common-mode
source impedances (100 
). This guarantees that any common-mode noise is induced equally
into the positive (+) and negative (-) legs of a differential input in order to take full advantage of
common-mode noise rejection.
 7. Power Supply
The controllers use only a nominal amount of power. Therefore, full wave bridge rectifier Z1 and
regulators U13 and U14  are all that are needed to develop the quiet, stable +/- 15 volt supply
needed by the op-amps.
8. Turn On/Off Muting Circuit
Relays K1 and K2 clamp the outputs and are controlled by three sections of quad comparator
U15. U15 (pins 8, 9 and 14) drives the relay control transistor Q1 by pulling the relay-coil termi-
nal to nearly 15 volts . This energizes the relay for normal audio operation.  At power on, U15
(pins 8, 9 and 14) is prevented from energizing the relay until capacitor C152 can be charged
up sufficiently. This takes about 1.2 seconds, and mutes any turn-on transients. At power off,
U15 (pins 2, 4, and 5) quickly detects the loss of AC power and causes Q1 to snap quickly off.
This de-energizes the relay in about 100 ms, before any transients can reach the output.
9. Troubleshooting Tips
If a differential output test generator isn't available, connect the generator ground to the
controller's ground terminal, and the generator hot lead to the negative (-) input terminal.
Leave the positive (+) terminal unconnected.
If you need to connect the controller outputs to a single-ended (not differential) instrument,
connect the controller's output ground to the instrument ground, and the controller's positive (+)
output terminal to the instrument hot pin. Leave the negative (-) output pin unconnected.
Since the controllers are two channel devices, you can troubleshoot any problem occurring in
only one channel more easily by applying the identical signal to both channel 1 and channel 2
inputs and tracing stage by stage, comparing the signal as it passes through the various
stages. In general, the corresponding channel 1 and channel 2 stages share the left and right
THEORY OF OPERATION
hand sides of the respective op-amps. This makes it easier to compare the stages. 
						

							7 With a nominal AC power input voltage (100, 115, or 230, depending on the country), the AC
voltages at the transformer secondary should be:
between P3-1 and P3-3:  41.3 Vrms
With a cold (i.e. -room temperature) power transformer, you should expect primary and second-
ary resistances of:
For the 100 VAC version:
between P2-1 and P2-2:  41.8 

between P3-1 and P3-3:  6.9 

For the 115 VAC version:
between P2-1 and P2-2:  45.4 

between P3-1 and P3-3:  6.3 

For the 230/240 VAC version:
between P2-1 and P2-2:  195 

between P3-1 and P3-3:  7.1 

Other DC voltages are of use in troubleshooting:
Turn On/Off Muting Circuit
Typical DC voltages after 2 seconds wake up
U15-1 Section not used
U15-2 +13.5
U15-3  -15.0
U15-4  +.15
U15-5  +3.2
U15-6 Section not used
U15-7 Section not used
U15-8  +7.5
U15-9 +13.5
U15-10 +7.5
U15-11 +9.7
U15-12 -15.0
U15-13 +13.5
U15-14 -13.9
Q1-collector-14.7
Power Supply
U13-1 +26.0
U14-2  -26.0
THEORY OF OPERATION 
						

							8
THEORY OF OPERATION
Figure 1. Block Diagram 
						

							9
DISASSEMBLY/ASSEMBLY  PROCEDURES
402® and 802® 

 First Variation (Removable Front Panel)
1. Top cover Removal
1.1 Remove the two screws (7) that secure
the top cover (2) to the front panel (9).
1.2 Remove the two screws (1) that secure
the top cover to the rear of the chassis.
1.3 Lift up the rear of the top cover and
slide it out from under the front panel.
2. Top cover Replacement
2.1 Place the top cover (2) onto the unit and
slide it under the front panel (9).
2.2 Secure the rear of the top cover using
the screws (1) removed in procedure 1.2.
2.3 Secure the front of the top cover using
the two screws (7) removed in procedure
1.1.
3. Front Panel Removal
3.1 Perform procedure 1.
3.2 Remove the two wires (14) that connect
to the power switch (10).
NOTE: On some earlier versions there was
hot melt applied to the wires.
3.3 Remove the two screws (7) that secure
the front cover to the bottom of the chassis.
3.4 Pull the front panel away from the
chassis.5. PCB Removal
5.1 Perform procedure 3.
5.2 Remove the 6 screws (5) that secure
the connectors (4) to the rear panel.
5.3 Disconnect the one line cord connector
(P1) and the two power transformer con-
nectors P2) and (P3).
NOTE: If the Opti-Voice
® PCB is installed
on the PCB assembly remove the connec-
tor from the Opti-Voice PCB.
5.4 Remove the 5 screws (3) that secure
the PCB assembly (15) to the chassis.
5.5 Squeeze the two metal posts (not
shown) located at the two front corners of
the PCB and lift up the PCB. Slide the PCB
assembly towards the front of the chassis
and lift it out.
6. PCB Replacement
6.1 Slide the PCB assembly (15) into the
front of the unit aligning the connectors (4)
to the rear panel. Push the two front
corners of the PCB on to the two metal
posts.
6.2 Secure the PCB assembly to the chas-
sis using the 5 screws (3) that were re-
moved in procedure 5.4.
6.3 Secure the PCB to the rear panel using
the 6 screws (5) that were removed in
procedure 5.2.
6.4 Reconnect all connectors removed in
procedure 5.3.
6.5 Perform procedure 4. 4. Front Panel Replacement
4.1 Slide the front panel (9) onto the chas-
sis.
4.2 Replace the two screws (7) that secure
the front panel (9) to the bottom of the
chassis.4.3 Connect the two wires (14) to the
power switch (10).
4.4 Perform procedure 2. Note: Refer to Figure 2 for the following
procedures. 
						

							10
DISASSEMBLY/ASSEMBLY  PROCEDURES
7. Transformer Removal
7.1 Perform procedure 1.
7.2 Disconnect the two wire harnesses (P2)
and (P3) from the transformer to the PCB.
7.3 Remove the two 11/32” hex nuts (12)
that secure the transformer (13) to the
chassis.
7.4 Lift the transformer up and away from
the chassis.
8. Transformer Replacement
8.1 Place the transformer (13) into the
chassis aligning it to the studs.
Note: Proper orientation is required for the
transformer wire harnesses.
8.2 Secure the transformer to the chassis
using the two 11/32” hex nuts (12) that was
removed in procedure 7.3.
8.3 Connect the two wire harnesses from
the transformer to the PCB.
8.4 Perform procedure 2.402
® and 802® 

 First Variation (Removable Front Panel)
Note: Refer to Figure 2 for the following
procedures.