Bose FreeSpace 6 User manual

1
Table of Contents
ELECTROSTATIC DISCHARGE SENSITIVE (ESDS) DEVICE HANDLING.................................................... 2
SAFETY INFORMATION................................................................................................................................... 3
IDENTIFICATION OF UNIT UNDER TEST....................................................................................................... 4
SPECIFICATIONS............................................................................................................................................. 5
THEORY OF OPERATION................................................................................................................................ 7
DISASSEMBLY/ASSEMBLY PROCEDURES................................................................................................. 11
Main Assembly Procedures ....................................................................................................................... 11
Figure 1. Main Disassembly/Assembly Exploded View............................................................................. 12
Flush-Mount Loudspeaker Procedures ..................................................................................................... 15
Figure 2. Flush-Mount Loudspeaker Exploded View ................................................................................. 16
Surface-Mount Loudspeaker Procedures.................................................................................................. 16
Figure 3. Surface-mount Loudspeaker ...................................................................................................... 17
TEST PROCEDURES..................................................................................................................................... 18
Main Assembly Test Procedures................................................................................................................ 18
Loudspeaker Test Procedures ................................................................................................................... 20
PART LISTS AND EXPLODED VIEWS........................................................................................................... 21
Main Assembly Part List (Figure 4)............................................................................................................ 22
Figure 4. MainAssembly Exploded View................................................................................................... 23
RemoteAssembly Part List (Figure 5)....................................................................................................... 24
Figure 5. Remote Assembly Exploded View.............................................................................................. 24
Main Assembly Packaging Part List (Figure 5).......................................................................................... 25
Figure 6. MainAssembly Packaging Exploded View................................................................................. 26
Flush-mount Assembly Part List ................................................................................................................ 27
Figure 7. Flush-mount Exploded View....................................................................................................... 27
Flush-mount Packaging Part List............................................................................................................... 28
Figure 8. Flush-mount Loudspeaker Packaging Illustration........................................................................28
Surface-mount Assembly Part List ............................................................................................................ 29
Figure 9. Surface-mount Loudspeaker Illustration..................................................................................... 29
Surface-Mount Packaging Part List ........................................................................................................... 30
Figure 10. Surface-mount Loudspeaker Packaging .................................................................................. 30
FreeSpace®6 Electrical Part List, PCB P/N 177300, Revision 0 .............................................................. 31
FreeSpace 6 Electrical Part List, PCB P/N 177300, Revision 1 .............................................................. 40
SCHEMATICS AND PCB LAYOUTS............................................................................................................... 49
Sheet 1, PCB IO1 Music Inputs (PCB 177300, Revisions 0 and 1) .......................................................... 50
Sheet 2, PCB IO1 Music Compressor (PCB 177300, Revisions 0 and 1)................................................. 51
Sheet 3, PCB IO1 Board Page Processor (PCB 177300, Revisions 0 and 1) .......................................... 52
Sheet 4, PCB IO1 Board Music/Page Mixing (PCB 177300, Revisions 0 and 1) ...................................... 53
Sheet 5, PCB IO2 Board Line Outputs (PCB 177300, Revisions 0 and 1)................................................ 54
Sheet 6, PCB IO2 Board Remote Volume (PCB 177300, Revisions 0 and 1) .......................................... 55
Sheet 7, PCB IO2 Tone Control and Surface EQ (PCB 177300, Revisions 0 and 1)................................ 56
Sheet 8, PA Board Dynamic EQ and Limiter Processor (PCB 177300, Revisions 0 and 1)...................... 57
Sheet 9, PA Board Speaker EQ (PCB 177300, Revisions 0 and 1) .......................................................... 58
Sheet 10, PA Board Power Supply and Amp(PCB 177300, Revisions 0 and 1) ....................................... 59
Sheet 11, Remote Board (PCB 177300, Revisions 0 and 1) ..................................................................... 60
FreeSpace Business Music System Manual pn 181816

2
CAUTION: THE FREESPACE®6 BUSINESS MUSIC SYSTEM
CONTAINS NO USER-SERVICEABLE PARTS. TO PREVENT
WARRANTY INFRACTIONS, REFER SERVICING TO WARRANTY
SERVICE STATIONS OR FACTORY SERVICE.
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.
ELECTROSTATIC DISCHARGE SENSITIVE (ESDS)
DEVICE HANDLING
This unit contains ESD sensitive devices. We recommend the following precautions when
repairing, replacing or transporting ESD sensitive 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.

3
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 parts that
have critical characteristics recommended by the manufacturer.
2. Perform leakage current or resistance measurements to determine that exposed
parts are acceptably insulated from the supply circuit before returning the unit
to the customer. 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 and then in
OFF position, measure from a known earth ground (metal waterpipe,
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 milliampere. Reverse the unit power
cord plug in the outlet and repeat test. ANY MEASUREMENTS NOT WITHIN
THE LIMITS SPECIFIED HEREIN INDICATE A POTENTIAL SHOCK HAZARD
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 between 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 poss-
ibility of a shock hazard, and the unit must be repaired and rechecked before it
is returned to the customer.
SAFETY INFORMATION

4
IDENTIFICATION OF UNIT UNDER TEST
NOTE: The PC board revision level number is marked on the PC board as follows:
1
When servicing a FreeSpace®6 take notice of the following attributes:
• PC Board Part Number
• Revision Level Number of the PC Board
• Unit's Voltage Variation Type (100V,120V, 220V, 240V).
There are two types of FreeSpace 6 units manufactured. If the unit you are servicing has a
switch denoted by surface/flush mount speaker icons in block 12 of the front panel, then you
have a 2 EQ unit. If not, then you have a 1 EQ unit.
The EQ changes are represented on page 56 (Sheet 7, PCB Tone Control and Surface EQ)
of this manual. The 2 EQ unit will have all optional components (OPT) populated on the I02
board. The 1 EQ unit will be depopulated.
Refer to the applicable part list and schematics as follows:
• There are two Electrical Part Lists, one for Revision 0 and one for Revision 1 of PCB
177300.
•The PCB Schematics and Layout views supplied with this service manual are applicable
for Revisions 0 and 1of PCB 177300.

5
SPECIFICATIONS
Input Sensitivity Music Input: 200mV
Page Input: 200µV
Power Output 16W into 2Ωload
Power Requirements 120V or 220-240V ~ 50/60 Hz
Remote Volume
Control Value 10kΩ, Audio taper
Music Input Impedance Channel A: Balanced: 32kΩ
Channel A: Unbalanced: 11kΩ
Channel B: Unbalanced: 10kΩ
Page Input Impedance Balanced: 9kΩ
Unbalanced: 1kΩ
Page and Line Output
Impedance 400Ω
Page Gain 0dB to 80dB adjustable
Frequency Range 80Hz - 16kHz
Noise (line into loudspeaker outputs): 20Hz - 20kHz bandwidth; -65dBV at
20dB gain into 10kΩload
Frequency Response 20Hz - 20kHz, ±1dB, referenced to
1kHz at line outputs
Dimensions Module 4.0" H x 7.5" W x 15.0" D (10.16 x
19.05 x 38.10 cm)
Flush-mount Speaker Assembly: Flange Dia.: 6.25" (15.9 cm)
Hole Dia.: 5.75" (14.6 cm)
Depth: 6.5" (16.5 cm)
Surface-mount Speaker Assembly: 3.3" H x 7.6" W x 6.4" D (8.3 x 19.3 x
16.33 cm)
Weight Module: 11.3 lb. (5.14 kg.)
Flush-mount Speaker Only: 2.1 lb. (.97 kg)
(Including Mounting Hardware): 4.2 lb. (1.9 kg)
Surface-mount Speaker (Including
Mounting Hardware): 2.5 lb. (1.2 kg)
Driver Flush-mount & Surface-mount Speaker: 2.5" Full-range Driver
Beamwidth Flush-mount & Surface-mount Speaker: 150°@ -6 dB
Performance Specifications

6
Performance Specifications (Continued)
Maximum Acoustic
Output 82dB-SPL in 20,000 cubic feet room with a speech band RT60 of 0.5 secs
Opti-voice® Paging
Circuitry Ensures a constant paging level over a
30dB dynamic range by compressing
the page signal. Music gradually
returns to original level after page.

7
1. OVERVIEW
The FreeSpace®6 business music system delivers high-fidelity music and paging in commer-
cial environments. The FreeSpace 6 components have been engineered to work together as a
system. The electronics have separate compressors for music and paging sources that de-
crease the dynamic range of the audio signal, thereby increasing the audibility of musical
passages and paging anouncements. A protective compressor in the power amplifier prevents
audible overload distortion if the user attempts to play the system too loud.The system has the
following features:
• High-fidelity sound over a large area
• Active equalization, music compression, and system overload protection
• Opti-voice®circuitry for high quality paging capability
• Remote control of volume and source selection
The circuit descriptions that follow are grouped according to the PCB section and sheet num-
ber of the schematic.
2. IO1 PCB
2.1 IO1 PCB Schematic Sheet 1
Music Input A is routed through a differential input amplifier (U4) which accepts balanced
sources or unbalanced sources. The amplifier output is passed through a gain trim pot and
presented to the Music A/B selector. Music Input B is fed directly to a gain trim pot and then to
the Music Input A/B selector.
Music Selector A/B is a 2P2T analog switch, implemented with a special switching op amp
(U11,U12)). The op amp is controlled by the signal SELECTB.
The Music Selector Interface is a two transistor circuit that normally selects Music Input A. With
the Remote Selector switch open, transistor Q2 is on, which turns on D4, the Source A LED,
pulling SELECTB low. This turns off Q1, keeping its LED off. When the Remote Selector switch
is closed, Q2 is turned off, allowing Q1 and D3 (the Music B LED) to turn on. This moves
SELECTB high and turns off the Source A LED. When SELECTB is high, current is no longer
sunk from U11 and U12’s SW pin, and they select Music Input B.
2.2 IO1 PCB Schematic Sheet 2
On their way to the compressor, the left and right music signals pass through a stereo/mono
switch, S1. After the compressor (U7 and part of U6), the music signals leave this sheet. The
compressor is enabled by a logical function of SELECTB, Music Compressor A, and Music
Compressor B enable switches. The logic (U8) determines that the compressor will be enabled
only for a music source if that source is the one currently selected and if it has been enabled
for compression via its switch (S2 or S3).
The compressor offers a maximum gain of about 20dB for very low level signals and operates
at a 2:1 slope. It slowly raises the level of quiet musical passages, and quickly reduces the
level of loud passages. The two channels are cross coupled to maintain a centered stereo
image. By selecting the rectifier input source as a DC current, the compressor is disabled (U9).
THEORY OF OPERATION

8
The two sections of U15 are used to control a bi-colored Music-Compressor LED, D2. As long
as the compressor is enabled, the LED glows green to indicate how active the compressor is.
Whether or not the compressor is enabled, the LED is also acting as a watch dog and will flash
red if the signal presented to the music compressor is too great for it to handle.
2.3 IO1 PCB Schmatic Sheet 3
The Page Input is presented to a differential amplifier (U2) that can handle a wide range
of source voltages, as well as balanced or unbalanced sources. S5 determines the gain of the
first stage (0dB or 30dB). The page signal next passes through U2, where it can be given a
gain of 0 to 30dB, as determined by R1. At S4, the page signal is routed either through
another variable gain stage (U2, gain adjustable from 0 to 20dB), or through the Opti-voice®
compressor. The Opti-voice compressor (U5 and part of U6) provides anywhere from 20dB of
gain to 10dB of loss, depending upon the signal level.
Finally, the output of S4 is passed through the Page Muting stage (part of U10, Q3, and Q4), in
which it is muted unless the page trigger circuits have detected a signal. The Page Output
connector (J2) is driven by part of U10, acting as a buffer stage.
The two sections of U3 are used to control a bi-colored Opti-voice Compressor LED, D5. As
long as the compressor is enabled; the LED glows green to indicate how active the compres-
sor is. Whether or not the compressor is enabled, the LED is also acting as a watch dog and
will flash red if the signals at U2’s outputs are too great for the compressor to handle.
2.4 IO1 PCB Schematic Sheet 4
The Page Trigger circuits first offer a user sensitivity adjustment, via R3, then provide up to
26dB of gain for the trigger signal. V13, Section B acts as a threshold comparator and a peak
hold circuit. For signals exceeding the threshold, the circuit changes state rapidly, and holds
the new state long enough to ride through syllabic and inter-word pauses in paging. The two
remaining sections of U13 provide a fade-back time constant for the music and adjust the
control voltage levels to suit the muting transistors Q3,4,5,6 and 7.
Two sections of U14 mix the music and page signals, while the other two sections of U14
provide the mono versions of the music signals and the music+page signals. Switch S9 en-
ables paging in the signals fed on to the speaker outputs. R2 allows for adjustment of the page
level relative to the music.
3. IO2 PCB
3.1 IO2 PCB Schematic Sheet 5
S7, the Line Output Mode switch, selects the signals sent on to U200 and the Line Outputs.
Relay K1, controlled by Q201 and Q200, mute the Page and Line Outputs during power on
and power off transitions to prevent glitches from reaching the outputs.

9
3.2 IO2 PCB Schematic Sheet 6
The remote volume control function is implemented on this sheet with a dual VCA, IC U201,
and its buffer, U202. (An alternate part could be used in U201A, but this is a manufacturing
alternative, not a field service alternative.) U201 is controlled by a current sourced into the
signal VCA, coming from Sheet 7. When VCA is about 2mk, gain is at its maximum, which is
unity (0dB). When the current into VCA is zero, the gain is essentially off (-80dB or so).
S4 and its related components are factory set gain trims.
3.3 IO2 PCB Schematic Sheet 7
Transistors Q202, Q203 and related components transform the variable resistance of the
remote volume control into the current source that feeds signal VCA, on Sheet 6.
U205 is a conventional bass and treble control, while U203 is an equalizer stage intended to
provide the EQ adjustment needed when FreeSpace® 6 systems are configured with Surface-
mount loudspeakers (as opposed to the Flush-mount FreeSpace 6 speakers).
4. Power Amplifier PCB
4.1 PA PCB Schematic Sheet 8
U301, part of U300, and U302 implement a acoustically correct low frequency compensation
for more natural bass. The other two sections of U300 process the signal CD-DIA (“clip-
detect-diagnostic”, see Sheet 10) into a control signal that is sent through P2A, remote volume
control circuit on Sheet 7 . CD-DIA becomes active when the power amplifiers are driven into
clipping. This in turn causes the remote volume control circuit to be turned down so that clip-
ping ceases.
4.2 PA PCB Schematic Sheet 9
U303 combines the low frequency compensation signal with the full range signals and then
equalizes them to compensate for room acoustic and speaker driver characteristics.
4.3 PA PCB Schematic Sheet 10
U304 and U307 are power amplifiers with differential outputs. Both amplifier outputs can
deliver 16 watts into the nominal 2 ohm load of a pair of FreeSpace 6 speakers. The CD-DIA
pins are pulled low when the amplifiers begin to clip. This is used to control a compressor
implemented on Sheet 9 and Sheet 7.
D306 develops the DC power supply for the power amplifier. Q305 and associated compo-
nents constitute a shunt voltage regulator which only conducts in the unlikely event of both a
high power line voltage and a low or no signal output case. It holds 18V maximum which is
presented to U304 and U307.
D305, U305, and U306 are the +/-15V supply for all the circuits except for the power amplifier.
The power transformer secondary plug can be inserted two ways; one way will handle a nomi-
nal 120VAC main, the other a nominal 240VAC main. The two orientations of this plug are
noted on the PCB.

10
5. Remote PCB
REM PCB Schematic Sheet 11
The circuits on this sheet are contained on a small PC board inside the remote control. The
potentiometer is wired as a 10K ohm rheostat and controls the remote volume control circuits
on Sheet 6, while the SPST switch controls the Music Selector on Sheet 1.

11
2.2 Align the screw holes of the top cover
with the screw mounts located on the base.
Also align the four metal tabs on the base
with the tab slots on the cover. There are
also six metal tabs located on the bottom
edges of the cover that must be aligned
when the cover is finally seated.
2.3 Slide the cover down over the base
until the screw holes are aligned and all tab
slots are locked into place.
2.4 Secure the chassis top cover (3) by
tightening two silver screws (2) with a
phillips-head screwdriver.
2.5 Position the three bottom tabs on the
chassis cover into the slots located in the
chassis base. Press the chassis cover
down over the chasis-top cover to secure it.
3. Amplifier PCB Removal (Chassis Base)
3.1 Remove the Chassis Cover/ Top Cover
(Procedure 1) .
3.2 Separate the chassis-top cover from
the base by disconnecting both two-pin
cables from the Amp PCB's (8) P3A and
P3B connectors. Disconnect the eight-pin
cable from the Amp PCB's P2A connector.
3.3 Disconnect the following cables:
• Disconnect the transformer's five-pin
primary cable from the Amp PCB's P7
connector.
• Disconnect the transformer's five-pin
primary cable from the Amp PCB's P4
connector.
IMPORTANT: Be sure to notice the orien-
tation of the transformer's five-pin primary
cable. Pin 1 is keyed to pin 1 of Amp PCB
connector P6 (or P7 depending upon the
unit's applicable voltage rating).
Main Assembly Procedures
Note: Certain parts will be referred to in
these procedures. The numbers in paren-
theses represent individual parts called out
in Figure 1. The callout numbers corre-
spond to those on the part lists.
1. Chassis Cover/Top Cover Removal
1.1 Place the amplifier flat on the work-
bench with the Bose®logo in the upper-left
corner.
1.2 Detach the chassis cover (1) by holding
both corners and pulling upward. Once the
cover is loosened, slide the bottom tabs out
and away from the unit.
1.3 Use a phillips-head screwdriver to
remove two silver screws (2) securing the
chassis top cover (3).
1.4 Gently lift the right side of the chassis
top cover up at a 45°angle and pull to the
right and up. This is done to clear the left
screw mount away from the Amp PCB (8)
when the cover is lifted off.
IMPORTANT: Be careful not to pull the
three cables connected to the Amp PCB (8)
assembly. They must be disconnected
before final removal of the chassis-top
cover.
2. Chassis Cover/Top Cover Replacement
2.1 Place the chassis-top cover (3) over the
chassis base (4). Align the cover so that
the left-side screw mount of the chassis
base will slide between the IO1 PCB (8)
and the inside surface of the chassis-top
cover. Otherwise there will be difficulty
securing the cover.
DISASSEMBLY/ASSEMBLY PROCEDURES
• Disconnect the main power two-pin
primary cable from the Amp PCB's P4
connector.

12
Figure 1. Main Disassembly/Assembly Exploded View
2X
CONNECT
TO P5
SECONDARY
PRIMARY
P5
P3A
P3B
CONNECT
TO P3B
BLU./GRY.
P2
9
11
5
2
5
55
12

6
7
8
13
4
10
3
CONNECT
TO P3A
RED/BLK.
8
CHASSIS COVER
CHASSIS
TOP COVER
IO1 PCB
CHASSIS
BASE
8
IO2 PCB
AMP ASSY
COUPLER
BAR
1

13
3.4 Remove two black screws (5) from the
Amp PCB (8) and three black screws (6)
from the Heatsink (7).
3.5 Remove the Heatsink/Amplifier PCB
Subassembly from the chassis base.
3.6 Place the subassembly on the work-
bench with the heatsink (7) fins down.
3.7 Remove three black decoupler bar
screws (5) that connect the heatsink to the
Amplifier PCB.
3.8 Remove the Amplifier PCB (8) from the
heatsink.
4. Amplifier PCB Replacement (Chassis
Base)
IMPORTANT: Thermal grease should be
applied to the heatsink before seating the
PCB.
4.1 Place the Amplifier PCB (8) onto the
heatsink (7). Align the coupler bar (9) screw
holes with the screw holes of the heatsink.
The PCB should be component side up
with the power devices resting on the inner
side of the heatsink.
4.2 Secure the coupler bar and Amplifier
PCB to the heatsink by tightening three
black screws (5).
IMPORTANT: Make sure that the coupler
bar does not make contact with the metal
tab of transistor Q305.
4.3 Place the Heatsink/Amplifier PCB
subassembly solderside down into the
chassis base. Secure the upper-left hand
corner of PCB onto the standoff snap.
Secure the subassembly to the chassis
base by tightening two black screws (5) on
the Amp PCB and three black screws (6)
on the heatsink.
4.4 Connect the following cables:
• Connect the main power's two-pin cable
to the Amp PCB's P5 connector.
• Connect the tranformer's secondary five-
pin cable to the Amp PCB's P4 connector.
• Connect the transformer's primary five-pin
cable to the Amp PCB's P7 connector.
IMPORTANT: Pin 1 of the transformer's
five-pin primary cable is keyed to pin 1 of
Amp PCB connector P6 (or P7 depending
upon the unit's applicable voltage rating).
4.5 Install the Chassis Cover/Top Cover
(Procedure 2).
5. Transformer Removal
5.1 Remove the Chassis Cover/Top Cover
(Procedure 1).
5.2 Disconnect the following cables from
the transformer:
• Disconnect the transformer's five-pin
primary cable from the Amp PCB's P7
connector.
• Disconnect the transformer's five-pin
primary cable from the Amp PCB's P4
connector.
5.3 Remove transformer cables from cable
clamps (12) and lift the transformer from
the chassis base (4).
6. Transformer Replacement
6.1 Place the transformer (10) into the
recess of the chassis base and align it with
the chassis base mounting holes. Make
sure that the primary side is facing the IEC
Connector Assembly
(13).
6.2 Place the two transformer clips (11)
over the transformer's mounting tabs.
Secure the transformer to the chassis base
by tightening the two black screws (5).

14
8. IO1 & IO2 PCB Replacement (Chassis
Top)
8.1 Connect the 12-pin cable to connector
P1A on the larger board.
8.2 Carefully align both board's connectors
into the chassis top cover and snap them
onto the chassis standoffs.
8.3 Secure the two-pin and the eight-
pin cables into the cable clamps (12).
8.4 Replace six black screws (5) and
tighten to secure both boards.
8.5 Install the Chassis Cover/Top Cover
(Procedure 2).
6.3 Connect the following cables:
• Connect the transformer's five-pin sec-
ondary cable to the Amp PCB's P4 connec-
tor.
• Connect the transformer's five-pin pri-
mary cable to the Amp PCB's P7 connec-
tor.
IMPORTANT: Pin 1 of the transformer's
five-pin primary cable is keyed to pin 1 of
Amp PCB connector P6 (or P7 depending
upon the unit's applicable voltage rating).
6.4 Install the Chassis Cover/Top Cover
(Procedure 2).
7. IO1 & IO2 PCB Removal (Chassis Top)
7.1 Remove the Chassis Cover/Top Cover
(Procedure 1).
7.2 Remove six black screws (5) from both
Amplifier IO PCB's (8). Remove the IO2
PCB board first. Grasp it by the top cor-
ners, lift up and off the chassis-top's stand-
offs. (Note: The IO boards are connected
by a 12-pin cable. Do not attempt to sepa-
rate until both are removed).
7.3 Remove both two-pin and eight-pin
cables from the cable clamp (12) from the
inside of the chassis-top cover.
7.4 Grasp the IO1 PCB board by its top
corners, lift up and off the chassis-top's
standoffs. Position the board at a 45°angle
and carefully pull it back so that the I/O
connectors clear the top cover.
7.5 To separate boards, disconnect the 12-
pin cable from connector P1A on the larger
board.

15
Flush-Mount Loudspeaker Procedures
1. Flush-mount Loudspeaker
NOTES: Certain parts will be referred to in
these procedures. The numbers in paren-
theses correspond to the individual parts
called out in Figure 2.
1.1 Grille Removal
To remove the grille (Not Shown) take a
scribe or a small flat-head screwdriver to
grasp an edge of the grille. Gently lift the
grille out from the enclosure (2).
1.2 Grille Installation
Push the grille into the enclosure (2) until it
is flush with the rim of the enclosure.
Orientation of the logo is not necessary.
1.3 Driver Removal
A. Use Procedure 1.1 to remove the grille
from the enclosure (2).
B. Use a phillips-head screwdriver to
remove four screws (3) securing the driver
(4) to the enclosure's baffle (6). Carefully lift
the driver from the enclosure and cut the
wires as close to the terminals as possible.
1.4 Driver Replacement
A. Strip the terminal wires from the terminal
cup (5) and connect them to the replace-
ment driver (4). Connect the red wire to the
+ positive terminal and the black wire to the
- negative.
B. Align the driver so their four screw holes
align with the screw holes of the
enclosure's baffle (6). Secure the driver to
the enclosure (2) by tightening four screws
(3) with a phillips-head screwdriver.
C. Use Procedure 1.2 to return the grille to
the enclosure.
1.5 Terminal Cup Removal
A. Use a phillips-head screwdriver to
remove one screw (7) from the junction-box
cover.
B. Swivel the junction-box cover out to
expose the terminal cup (5) in the recess of
the speaker enclosure (2).
C. Use a phillips-head screwdriver to
remove three screws (3) that secure the
terminal cup to the speaker enclosure.
D. Use Procedure 1.3 to remove the driver
(4) from the speaker enclosure (2).
E. Disconnect the terminal wires from the
driver and remove the faulty terminal cup.
1.6 Terminal Cup Replacement
A. Use Procedure 1.4 to connect the
replacement terminal cup (5) to the driver
(4).
B. Place the enclosure (2) on its side. Fit
the terminal cup into the slot at the back of
the enclosure. See Figure 2 for the proper
orientation of the terminal.
C. While holding the terminal from the
inside of the enclosure, tighten three
screws (3) with a phillips-head screwdriver.
D. Use Procedure 1.4 to secure the driver
(4) to the enclosure.
E. Use Procedure 1.2 to secure the grille
to the enclosure.

16
Black
3
8
5
7
4
3
2
Red The Baffle is
Adhered to
Enclosure
Junction-Box
Cover
6
Item 1 on the 
Packaging Part List
Figure 2. Flush-Mount Loudspeaker
Exploded View
Surface-Mount Loudspeaker Procedures
1. Surface-Mount Loudspeaker
NOTE: The Surface-mount Loudspeaker
has only two removable and replaceable
parts, the grille and the grille's scrim cloth.
Refer to the Surface-mount Assembly Part
List for the grille and scrim cloth's order
numbers.
1.1 Grille Removal
Grasp one edge of the grille with a small
scribe and gently pull the grille from the
enclosure. The grille's scrim cloth is behind
the grille.
1.2 Grille Replacement
1. Place the scrim cloth inside the grille.
2. Place the grille over the twiddler section
of the enclosure (Refer to Figure 3 for the
correct orientation). Press the grille until it
snaps into place.

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Figure 3. Surface-mount Loudspeaker
Grille

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TEST PROCEDURES
Main Assembly Test Procedures
Test Set-Up Parameters
Switches
All switches are referenced by their block
diagram location on the top of the unit. Set
them according to the table below.
Block
No. Switch Description Setting(s)
1 Page Source Gain left (0dB)
2 Optivoice Compressor left(off)
5 Page Enables Left and
Right right(on)
7 Music Compressors A
and B forward(off)
9 Music Input Mode rear(stereo)
10 Line Output Mode center(Music
+Page)
Potentiometers
All potentiometers are referenced by
their block diagram location on the top of
the unit. Set them according to the table
below.
Block
No. Pot. Description Setting(s)
1 Page Source Gain
Trim ccw(0dB)
3 Page Trigger
Level cw(max)
4 Page Mix Trim cw(max)
6 Music A and B Source
Trim cw(max gain)
12 Treble and Bass Trim center(flat)
13 Volume Trim Right cw(max
gain)
Input Connections
Page Input
Connect the positive (+) side of an oscilla-
tor to the positive input terminal. Connect
the negative (-) side to the negative (-) and
common input terminals. Do this using
quick connectors (P/N180094) supplied
with the unit.
Music RCA Inputs A, B (Left and Right)
Connect the positive (+) side of an oscilla-
tor to the positive input terminal on the RCA
jack. Connect the negative (-) side to the
negative (-) and RCA jack ground sleeve.
Output Connections
Page and Line Outputs (Left and Right)
Connect the positive (+) side of the test
equipment to the positive (+) output termi-
nals. Connect the negative (-) side to the
negative (-) output terminals. Do this using
quick connectors (P/N180094) supplied
with the unit.
Speaker Output (Left and Right)
Use the same output connections as above
with a 2Ω/50Watt resistor as a load.
All test equipment should be isolated
from ground (floated).

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1. Page Input To Page Output Gain
1.1 Apply a 5 Vrms, 1KHz signal to the
Page Input.
1.2 Measure the Page Output. Should be
4.22 Vrms (+ .78 Vrms/ - .67 Vrms).
2. Page Input To Line Outputs Gain
2.1 Apply a 5 Vrms, 1KHz signal to the
Page Input.
2.2 Measure the left and right Line Output.
Should be 4.22 Vrms (+1.09 Vrms/ -.87
Vrms).
3. Music Input A to Line Outputs Gain
3.1 Apply a 500mV rms, 1KHz signal to the
MusicA left and right input.
3.2 Measure the left and right Line outputs.
Should be 4.47 Vrms (+.84 Vrms/ - .71
Vrms).
Note: Repeat this test for Music Input B.
To select Music Input B, short the remote
select input.
4. Music Input A to Speaker Outputs Gain
4.1 Apply a 10 mVrms, 2KHz signal to the
left and right MusicA input.
4.2 Measure the Speaker output. Should be
290 mVrms (+54mVrms/ - 46mVrms).
5. Frequency Response
5.1 Apply a 10 mVrms, 2KHz signal to the
left and right Music A Input.
5.2 Reference a dB meter to the Speaker
output and set level to 0 dBr.
5.3 Change the signal to 12.5 KHz.
5.4 Measure the left and right Speaker
output. Should be 5.1 dBr (±2.0 dB).
6. Noise
6.1 Set the volume control to Max.
6.2 With the source off, measure the left
and right Speaker output. Should be ≤5.6
mVrms.
7. Full Power Distortion
7.1 Apply a 130 mVrms, 800 Hz signal to
the left input.
7.2 Measure the distortion at the left
Speaker output. Should be ≤1% THD.
7.3 Change the frequency to 95 Hz and
adjust the applied signal to get 5.66 Vrms at
the left Speaker output.
7.4 Measure the distortion at the left
Speaker output. Should be ≤2 %.
Note: Repeat this procedure for the right
channel.
8. Separation
8.1 Apply a 100 mVrms, 800Hz to the right
MusicA Input. Terminate the left Music A
Input with a 50Ωresistor.
8.2 Measure the left Speaker output.
Should be ≤10 mV.
Note: Repeat this procedure for the right
channel.

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Figure 1. Input Terminals
Input Terminals
Loudspeaker Test Procedures
NOTE: These procedures apply to both Flush-mount and surface-mount loudspeakers. The surface-
mount loudspeaker is not repairable. If this loudspeaker fails the following tests contact your Bose®Field
Service Representative.
1. Rub and Tick Test
Apply a signal of 6.0 Vrms at 80 Hz to the input terminals of the loudspeaker. See Figure 1. No
extraneous noises such as rubbing or ticking should be heard. Replace any driver that has a rubbing or
ticking noise.
NOTE: There is a normal suspension noise. To distinguish between a rub or tick and suspension noise,
displace the cone slightly with your finger. If the rubbing can be made to go away or get worse, then it is a
rub or tick and the driver should be replaced. If the noise stays the same, it is a suspension noise and the
driver is fine. Suspension noise will not be heard with program material.
2. Air Leak Test
Apply a signal of 6.0 Vrms ±1V at 80 Hz to the speaker input terminals. See Figure 1. For at least 5
seconds, listen for air leaks around the driver, speaker terminals, and along all cabinet joints. Repair air
leaks as required.
3. Sweep Test
Sweep the oscillator from 50 Hz to 5 kHz at 6Vrms. There should not be any loud extraneous sounds. If
there are any loud buzzes or distortion, replace the driver. The whooshing noise from the port at around
80 Hz is acceptable.
NOTE: There should not be any buzzes or rattles from the internal connecting wires or components.
Redress any wire or component that buzzes.
4. Phase Test
NOTE: Supply voltage should only be momentarily applied to the speaker input terminals to avoid
possible damage to the speaker.
Apply a 6 Vdc ±1 Vdc signal to the speaker input terminals (see Figure 1). The driver should move
outward.