The Companion 3 multimedia speaker system is a stereo system designed to be used as a computer sound
system. It can be used with any analog audio source. It has a bass module with a 6.5 inch dual voice coil
woofer in a slot ported design. The two satellite speakers connect to the bass module and are easily mounted
to a monitor with brackets, or can be placed on a desk or other desired surface. A wired remote control pod is
used to control volume and mute/un-mute functions. It also has a second input and a stereo headphone output.
Manufacturing Information - Early Version / Later Version
There are two different versions of the Companion 3 - Early Version / Later Version. From the outside there is
basically no difference but the boards inside are different. Please note the differences are documented in the
Electronic Part list. If a part numbers has changed from the early version or a part number has been added to
the later version a number 4 will be shown in Notes column. The product codes can be used to determined the
version. The product code for the early version is 033935 and the product code for the later version is 033061.
These product codes are the first six digits of the serial number and are located on the bottom of the system.
The serial number should be used to determined where the system was manufactured before attempting a
repair.
Test Procedures ....................................................................................................................... 23-25
Theory of Operation ................................................................................................................. 26-28
Revision History .............................................................................................................................29
Theory of Operation ................................................................................................................. 26-28
Warranty
The Bose® Companion® 3 MultiMedia Speaker System is covered by a 1-year, transferable limited
warranty.
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.
Caution: The Companion 3 MultiMedia Speaker System contains no user serviceable parts.
To prevent warranty infractions, refer servicing to warranty service centers or factory service.
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Safety Information
1. Parts that have special safety characteristics are identified by the symbol on the schematics
or by special notes on the parts list. Use only replacement parts 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. 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 the American National Standards Institute (ANSI)
C101.1 “Leakage Current for Appliances” and the Underwriters Laboratories (UL) 6500/IEC 60056
paragraph 9.1.1. With the unit AC switch first in the ON position and then in the 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 milliamp. Reverse the unit power cord plug in the AC outlet and repeat the 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 testing 3 wire products, the resistance measured to the product enclosure should be
between 2 and infinite MOhms. Also, the resistance measured to exposed input/output connectors
should be between 4 and infinite MOhms. When testing 2 wire products, the resistance measured to
exposed input/output connectors should be between 4 and infinite MOhms. If it is not within the limits
specified, there is the possibility of a shock hazard, and the unit must be repaired and rechecked
before it is returned to the customer.
Electrostatic Discharge Sensitive (ESDS)
Device Handling
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 unprotected
devices into materials such as plastic, polystyrene foam, clear plastic bags, bubble wrap or plastic
trays.
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Specifications
Mechanical
Dimensions: Bass Module: 8 5/8 “H x 7 1/8” W x 14” D
(21.8 x 18 x 35.56 cm)
Satellite Speaker: 3 1/2” H x 2 1/2” W x 2 3/8” D
(8.89 x 6.35 x 6.10 cm)
Control Pod: 2 1/2 “D x 1 1/8” H
(6.35 x 2.79 cm)
Weight: Bass Module: 15.4 lbs (6.98 kg) unpacked
Satellite Speaker: 0.5 lbs (0.23 kg) each
Packaged System 19.95 lbs (9.06 kg) packed
Power Rating: USA/Canada: 115 VAC 50/60 Hz
Japan 100 VAC 50/60 Hz
Euro 230 VAC 50/60 Hz
Nominal System
Bandwidth:
Maximum SPL: 100 dB (A weighted) pink
Output: Bass: 60 Watts
Satellites: 18 Watts per channel
40 Hz to 15 kHz
noise signal
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Part List Notes
1. This part is not normally available from Customer Service. Approval from the Field Service Manager
is required before ordering.
2. The individual parts on the PCBs are listed in the Electrical Part list.
3. This part is critical for safety purposes. Failure to use a substitute replacement with the same
safety characteristics as the recommended replacement part might create shock, fire and/or other
hazards.
4. The part number listed was included in the latest version of the Companion 3. The Main board and
the Power board for the latest version can be identified by the part number stamped on the component side of the board.
Power Board - 285350-001
Main Board - 280066-001
5. The part number listed is an assembly part number. The individual parts of the assembly might not
be available separately.
6. This part is referenced for informational purposes only. It is not stocked as a repair part. Refer to
the next higher assembly for a replacement part.
PCB ASSY, PS, 100V, JAPAN
PCB ASSY, PS, 240V, EURO
*Capacitor C7 on the new power supply board may need to be replaced, see Service Bulletin 271885-B4
307872-011
307872-022
307872-033
1
1
1
4
4
4
7
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X2
16
4
17
1
2
3
6
5
10
15
78
11 12
X2
9
13 14
Figure 3. Packaging Exploded View
Item
Number
1 OWNER’S GUIDE US/CANADA
OW NER ’ S GUI DE 5 LA NG
2 BA G , PO LY, 14.38 x 9.87 x 2 mi l 1 03 351 1
3 PACKING TUBE, 4.75 x 2.75 x 7.69 273522 1
4 BASS MOD ULE ASSY, US/CANADA, 120V
BASS MODULE ASSY, EUR O, 230V
BASS MODULE ASSY, JAPAN , 100V
(Compl ete package, i ncl u des Amp M od
Assy.)
5 CONTROL POD (NON-REPAIRABLE) 307874-001 1 5
6 LINE CORD, 100 V, BLK, JAPAN
LINE C ORD, 120V, BLK, US/CANADA
LINE C ORD, 220V, BLK, EURO
LINE CORD , 23 0V, BLK, UK
LINE C ORD, 240V, BLK, AUS
7 BRACKET, SAT, LEFT 271880-001 1
8 BRACKET, SAT, RGHT 271881-001 1
9 CABLE, INPUT, 3.5MM, 6FT, BLK 2719 94-001 1
10 SCREW, MACH , M 4 x 0.5, PAN 272963-08 2
11 BA G , PO LY, 14.38 x 9.87 x 2 mi l 1 03 351 1
12 FASTENER, RD, CLR, 21MM OD, PSA 273164 2
13 FEET, CLEAR, SATELLITE 178321-04 16
14 FEET, RUBBER, BRACKET 260465 4
15 SAT ASSY, BLACK/GRAY 271827-019 2
16 CARTON, RSC, P RINTED 272410 1
17 PACKING, EPS, FILLERS 272409 2
L1 Choke, Common mode, with header 277667-001 4
L1 Choke, Common mode, with header 277667-001 Japan
L1 Choke, Common mode, with header 277667-001 Euro/UK/Aus
F1 FUSE, 4.0A, 125V, .60X.19, SLOBLO, JAPAN 135677-12
J1 CONN, HEADER, LOCKING, TOP ENTRY 193369-002
J2 CONN, HEADER, 3.96mm, 7-pin 272385-07
J3 CONN, HEADER, 3 POS, .156 133220-03
J5 CONN, AC LINE, PC MOUNT 272684-001
J5 CONN, AC LINE, PC MOUNT 277580-001 Japan/Euro
J6 HEADER, SIDE ENTRY, LOCKING, ALT 272685-07A
Description Part Number Note
FUSE, 3.15A, 250V, 5.5X21mm, SLO-BLO, US
135677-12
298780-3150
3
3
3
3
3
3
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Disassembly Procedures
1. Module Assembly Removal
1.1 Remove the knob from the unit.
1.2 Peel back the label and remove it.
Note: Use double side tape like 3M
double-coated tape number 655 when
replacing the label or use a new label.
1.3 Remove the three silver Phillips-head
screws located on the right hand side (under
the label) and the five Phillips-head or T-15
Torx head screws around the heat sink fins.
1.4 Slide the electronic module back slightly.
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Disassembly Procedures
1.5 Disconnect the two connectors
shown and remove the module
assembly.
Speaker
Connector
Transformer
Connector
1.6 Disconnect the two connectors on
the power supply PCB.
1.7 Remove the seven T-15 Torx
screws shown, to remove the power
supply PCB.
Note: The PCB is mounted on standoffs which will become loose when
removing the screws.
Note: The main PCB is glued to the
heat sink assembly however it can be
repaired without having to remove it.
Power supply PCB
ConnectorMain PCB
Connector
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2. Power Transformer Removal
2.1 Remove the module assembly,
perform procedure 1.
2.2 Remove the bolt at the center
of the power transformer.
2.3 Remove the transformer and
shield-can from the bass box.
Note: If the new power transformer has a blue mark on it, align
the mark toward the PCB assembly for best performance. Refer to
the service bulletin, part number
271885-B1 for more details.
Disassembly Procedures
3. Woofer Removal
3.1 The Grille on the bass module is glued
into place. The woofer is not replaceable.
Replace the bass box assembly if the
woofer is defective.
4. Satellite Removal
4.1 Satellite speakers are not repairable.
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Test Procedures
Test Equipment required:
1. Audio Signal Generator
2. Oscilloscope
3. Digital Multimeter
Test Set up
Connect the satellites to the output jacks on the bass module.
Connect the control pod to the DIN jack on the bass module.
Connect a signal generator to the audio input cable and connect the cable to the input jack on the
bass module.
1. Bass Module Air Leak test
1.1 Apply a 40 mVrms, 40 Hz signal to the input of the bass module.
1.2 Set the volume knob on the control pod to maximum (fully clockwise), and set the bass control to
it’s center detent (flat) position.
1.3 Listen carefully for air leaks along all glued joints, around the heat sink, connectors and at the
woofer mounting location.
1.4 Repair any air leaks around the heat sink and connectors. Replace any bass module that has air
leaks around the bass box or woofer mounting location.
2. Bass Module Sweep Test
2.1 Apply a 200 mVrms, 100 Hz signal to the input of the bass module.
2.2 Set the volume knob on the control pod to maximum (fully clockwise), and set the bass control to
it’s center detent (flat) position.
2.3 Listen carefully as you sweep the bass module from 100 Hz to 300 Hz, then from 300 Hz to 100
Hz.
2.4 Listen carefully for buzzes, rattles, or other extraneous noises from the woofer, cabinet, plastic
trim parts, or heat sink. A slight whooshing sound from the port (at approximately 45 Hz) is acceptable.
2.5 Repair any noise heard from around the heat sink and connectors. Replace the bass module if it
has noises from the woofer or cabinet area.
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Test Procedures
3. Bass Module Tone Control Test
3.1 Apply a 90 mVrms, 100 Hz signal to the input of the bass module.
3.2 Set the volume knob on the control pod to maximum (fully clockwise), and set the bass control to
it’s center detent (flat) position.
3.3 Rotate the tone control fully clockwise and counter clockwise.
3.4 Verify that the bass level cleanly increases and decreases in level (without any scratchy noise).
4. Satellite Sweep Test
4.1 Apply a 2 Vrms, 100 Hz signal to the input of the bass module.
4.2 Set the volume knob on the control pod to maximum (fully clockwise), and set the bass control to
it’s center detent (flat) position.
4.3 Sweep the satellite speakers from 100 Hz to 3 kHz then from 3 kHz to 100 Hz.
4.4 Listen carefully for buzzes, rattles, or other extraneous noises from the Twiddler™ speakers,
plastic satellite enclosure, grille, or internal wires.
4.5 Replace any satellite that is found to be defective.
5. Satellite Air Leak Test
5.1 Apply a 2 Vrms, 200 Hz signal to the input of the bass module.
5.2 Set the volume knob on the control pod to maximum (fully clockwise), and set the bass control to
it’s center detent (flat) position.
5.3 Listen carefully for air leaks along edges of the satellite and near the grille where the Twiddler
speaker is installed.
5.4 Replace any satellite that is defective.
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Test Procedures
6. Control Pod Functional Test
6.1 With the system completely set up, turn on the system using the power switch located on the bass
module.
6.2 Set the volume knob on the control pod to maximum (fully clockwise), and set the bass control to
it’s center detent (flat) position.
6.3 Touch the center of the control pod . Verify that the LED turns from green to orange and orange to
green with each touch.
6.4 Verify that the sound is muted and un-muted when the LED changes color and that there is no
audible pop when switching from mute to un-mute.
6.5 Rotate the control pod ring, verify that the volume increases and decreases and that the ring
moves smoothly.
6.6 Replace any control pod that is defective.
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Theory of Operation
The Companion® 3 Multimedia Speaker System is a 2.1 (two channel stereo with one channel
subwoofer) system designed to be used as a computer sound system.
The Bass Module electronics contain signal processing circuitry and the amplifiers for the woofer and
satellites. A 120 volt AC input (for US variant), 14 volt DC power supply powers the electronics. The
power supply is located on a separate PC board.
The signal processing electronics in the bass module include equalizers, bass summing, TrueSpace™
processing, level compression, to prevent clipping at high volume, and protection circuitry.
The crossover frequency between bass and satellites is 300 Hz. The system is rated at 60 watts to
the woofer and 18 watts to each satellite. The bass box is tuned to 45 Hz.
The following is a detailed description of the circuitry on the power supply, amp board, and remote
board.
1.0Power Supply (refer to the schematic diagram 271839)
The power supply is located on the heat sink of the module and is the smaller PCB of the two. The
120 volt AC is received from the AC inlet jack and switch at J1. The AC is fused by the 4 amp F1 fuse.
VR1 protects against high voltage surges. The 120 volts is sent out to the 15 VAC, 7 amp toroid
transformer mounted to the interior of the bass box on J2. The 15 VAC secondary voltage comes
back into the board on J2. The 15 VAC is converted to 15-20 volts DC by bridge rectifier BR1.
Q1, Q2 and Q3 form a pre-regulator to keep the DC output voltage at 14 VDC. The 13 volt zener D1
serves as a reference to Q1. When the input AC goes one diode drop above the zener voltage, Q1
turns on. This turns off Q2, allowing Q3 to turn off, which disconnects the input rectified AC from
charging C7, the 3300 uF filter capacitor above 14 volts. This makes the voltage at C7 stay at about
14 volts. C2, C3 and C4 slow down the turn on of Q3 to reduce interference from this circuit to the
amplifier.
When the rectified voltage is lower than 14 volts, Q1 turns off, turning on Q2 and then Q3, allowing
C7 to charge whenever the ratified voltage from BR1 is above the voltage left on C7. The 14 VDC is
sent to the amplifier board over J3.
RT1 is a 22K thermistor at room temperature. It is mounted on the heat sink between BR1 and Q3. It
senses the system temperature and sends a signal to the main amp board to help reduce system gain
when the heat sink is getting too hot.
2.0Main Amplifier Board (refer the schematic diagram 271838)
On sheet 1 of 3, location (D8), is the A input. U3, (D7) buffers the inputs to be sent to the remote
control through J308. The remote mixes the A with the B input, on the remote, and sends the signal
back to the main PCB though J308. The control pod is further described in section 3.
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Theory of Operation
2.0 Main Amplifier Board (continued) (refer the schematic diagram 271838)
The signals coming into J308 (C7) are sent to sheet 3 of 3 (L_VOL and R_VOL). Three amplifiers in
U201 (D8-4) are the equalizers for the right channel and U125, (A8-4) are the equalizers for the left
channel. U951 (C8-3) in conjunction with U950 (C-2), the voltage controlled amplifier, form the bass
summer and dynamic bass equalizer.
The three stage equalizers for the equalizer perform the bass cutoff, mid-range cut, and high end
boost, in that order. They are 4-pole Salen-Key elliptical filters.
The bass signal is formed from the two inputs summed and low pass filtered by U951. The bass level
is detected by U125, D951, D952, Q950, Q951 and Q952 (B-6) forming an active peak detector. C955
and C957 filter the detected peaks to form the control voltage for the VCA in U950. When the bass
level is very low, the signal is boosted by U951. U950 is in the negative feedback path for U951, and
when its gain is low, U951 gain goes up, boosting the bass. U950 gain goes down when control
current generated by Q952 goes down, as controlled by peak detector circuit.
Q953, Q954 and D954 (D-2) form the peak detector on the bass outputs. Peaks near the negative rail
are conducted through D954 and Q953 to charge C969. Voltage on C969 is converted to a current by
Q954 which controls the VCA in U950. U950 is in the negative feedback loop of U951, so when U950
gain is high, less bass is output. Near clipping detected by the peak detector is converted to high
current by Q954, causing high gain in U950, reducing the gain in U951 and less bass. R980 and
C969 determine the attack time of the compressor, and R981 and C969 determine the release time.
Also on sheet 3 of 3, U201 (A-3) is the virtual ground generator. The 10 volt line is divided by two
R225 and R226, filtered by C970 and C235, and input to U201. The 5 volts generated by U201 is
used by all the signal processing circuitry as the virtual ground reference.
The right and left outputs, EQ_R and EQ_L are sent to page 2 of 3 (B3). U102 (B3) forms the true
space processing and the satellite signal compressors. TrueSpace™ processing consists of U102B
and U102D which act a low pass filters with a -3 dB point of 3 kHz. This signal is subtracted from the
opposite channel signal by U102A and U102C.
R204 and R105 determine how much TrueSpace signal is subtracted. The 127K compared to the 10K
value of the main signal inputs gives a TrueSpace signal of -18 dB relative to the main signal. To keep
the levels the same in mono conditions, the same amount of low pass filtered signal is added back to
the main channel of itself, through R106 and R206.
The satellite compressor consist of D401, D402, and Q401 (D7) which detect the right and left channel level, charging C401 when the R+, R-, L+ and L- signals get near the negative rail. The compressor attack time is determined by R403, and the release time is determined by R404. When C401
charges negatively, Q402 and Q403 convert this to current which increases the gain of U401A and
U401B. U401 is in the negative feedback path of U102A and U102C, and higher gain reduces the
gain through the satellite channels. Therefore, high signal levels near clipping reduces the gain of the
satellite channels, compressing the signals.
The compressed signals are sent to the main amplifier on sheet 1 of 3 over signals Sat_Drv_L and
Sat_Drv_R. The bass signal from the bass compressor on sheet 3 of 3, BASS_DRV, is sent to two
stages of bass equalization at U3B and U3D (D7). These form the 40 - 50 Hz boost, and the 100 Hz
cut for the bass box equalization.
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Theory of Operation
2.0 Main Amplifier Board (continued) (refer the schematic diagram 271838)
The two satellite signals, and the bass signal are sent to the power Amp IC, U301 (C3). One channel
of the power Amp IC is used for each satellite, and the bass signal uses two channels of the power
chip to drive both of the woofer voice coils.
The Amp IC can provide up to 40 watts into 2 ohms per channel. The woofer coils are 2 ohms each,
and 60 watts total is specified for the woofer drive. Each satellite can receive 18 watts each into their
4 ohm impedance.
The mute signal from the remote unit comes in through J308, is slowed down by C314 to prevent
pops.
The 10 volts for the signal processing circuitry is generated by D301, a 10 volt zener, and Q303 in an
emitter follower configuration. Q303 is specified up to 500 ma, and the entire remote and signal
processor consumes about 100 ma.
For thermal protection, Q304, Q305, and Q307 (A5) process the voltage generated by the thermistor
on the power supply and R337 and generate a current that goes higher as the temperature rises. This
current is summed into the three compressors, reducing the gain through the system at high temperatures. This prevents the heat sink from getting too hot. R337 determines the voltage division ratio and
therefore the haet sink maximum temperature.
Q308 and Q309 (D5) form a voltage detector that determines when power has reached sufficient
voltage for proper power amplifier operation. If the DC voltage falls below 10 volts, the power amplifier
will be muted. This prevents power up and down pops.
3.0 Control Pod Remote (refer to schematic diagram 272092)
The remote receives the A input signal from the bass module over J4. This is summed with the B input
on the remote control by U2. U2 drives the volume control pot R31. The adjusted volume is sent to U4
to drive the headphone outputs J5 and connector J4 back to the bass module. U1 buffers the 5 volts
reference to the sleeve of J5. J5 is a switched jack, and the switch mutes the main speakers when a
headphone plug is inserted. This grounds the mute signal, which is active low.
U3 is a touch sensor switch. When the operator touches the touch sensor pad on the remote, which is
connected electrically to WT1 and WT2, the QT113 chip will sense this and toggle the standby line.
This changes the LED (DS1) color from yellow to green. The green led is always on, and the red led
glows during standby, as driven by Q1, to mix with the green to show yellow color. U3 output also
drives the standby line to the bass module power amplifier. Standby is active high on the remote, and
inverted in the bass module to the active low signal required by the power amplifier.
The remote amplifiers are powered by the 10 volt supply coming in at J4 from the bass module. The
virtual ground from the bass module comes in as the VCCD2 signal reference from the signal processing. ZD1 is a 4.7 volt zener which generates the local power supply voltage from the 10 volt input.
R41 is the current limiting resistor for ZR1. This 4.7 volts powers U3.
At each I/O connector, resistors, capacitors, diodes, and spark gaps are present on each signal to
protect against RF emissions, susceptibility, and ESD.
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SERVICE MANUAL REVISION HIST OR Y
Date Revision
10/03 00 Document released at revision
5/05 01 Later version part num b ers
5/05 02 Part number change to F1 on
6/05 03 Deletion of part numbers:
6/05 04 Part numbers for C7 and J5
9/05 05 Bass Module part number
11/05 06 Added part numbers for the
3/06 07 Changed part list notes on
4/07
6/07
8/07 09 Part number changes
3/12/08 10 Added fuse part number
6/15/09 11 Added transformer part
1/7/10 11 Changed part number 178321-
Level
08
08
Description of Change Change Driven By Pages
00
added to Manual
Power board.
277574-001 Main Board US
lat er version
280109-001 Main Board
EURO
.
added to include Overseas
art numbers.
changed becaus e of
manufacturin
Japan and Euro rear labels
page 4. Note number 6 now
ref ers to – part is f or
informational use onl
Main board part number
271861-1 replaced by 280109-
01.
New part number for power
supply board –
307872-011 – 120V
307872-022 – 100V
307872-033 – 240V