SUPPLEMENT

Bose® Model 1801/1800

Power Amplifier

Q4, part number 102428 and Q5, part number 102429 are no longer available with the lead length
needed for soldering to the PCB. Use the part numbers listed below when ordering these transis-
tors. Make a note in your Model 1801/1800 power amplifier service manual, part number 192527.

Reference Description Part Note

Designator Number
Q4 SIM, 2N2219 102428-1K 1
Q5 SIM, 2N5415 102429-1K 2

NOTE: The part numbers listed are kits. They include the following parts:

1. Q4 kit: 1 102428 transistor

3 264371 extension pins
1 192527-S1 supplement.

2. Q5 kit: 1 102429 transistor

3 264371 extension pins
1 192527-S1 supplement.

©
2001 Bose Corporation Supplement
10/2001 Part Number 192527-S1
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 Contents
Specifications ................................................................................................................................... 2
Safety Information ............................................................................................................................ 3
Electrostatic Discharge Sensitive (ESDS) Device Handling ........................................................ 4
Disassembly/Assembly Procedures ........................................................................................... 5-8
Test Procedures ............................................................................................................................... 9
Figure 1. 1801 Component Location .............................................................................................. 10
Figure 2. 1801 Side View ............................................................................................................... 10
Figure 3. 1800 Front Panel ............................................................................................................ 11
Figure 4. 1800 Rear View of Front Panel ....................................................................................... 11
Figure 5. 1801 Rear View of Front Panel ....................................................................................... 11
Figure 6. 1800 Rear Panel ............................................................................................................. 12
Figure 7. 1801 Rear Panel ............................................................................................................. 12
Part List Notes ................................................................................................................................ 13
Figure 8. 1801 Front Panel ............................................................................................................ 13
Part List ...................................................................................................................................... 14-17
Figure 9. 1801/1800 Block Diagram ............................................................................................... 18
Figure 10. LED PCB Layout ........................................................................................................... 19
Figure 11. LED PCB Schematic Diagram ...................................................................................... 20
Figure 12. Amplifier Schematic Diagram ........................................................................................ 21
Figure 13. Amplifier PCB Layout .................................................................................................... 22
Troubleshooting Guide .................................................................................................................. 23
Voltage Conversion Instructions .................................................................................................. 24
Service Bulletin ......................................................................................................................... 25-28

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.

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 SPECIFICATIONS

Mechanical
Dimensions: 1801 7 3/16" H x 18" W x 18 1/2" D
(Including Knobs)
1800 81/4"H x 19"W x 15"D
(not including handles)

Weight: 1801 82 lbs

95 lbs (shipping)
1800 80 lbs
91 lbs (shipping)

Power Requirements
Voltage: 105-125 AC USA, 210-250 AC EUR

Frequency: 50-60 Hz

Power Consumption: Minimum 60 watts

Normal 1000 watts
Maximum 1960 watts

Integral Design™
Amplifier
Output : 250/250 watts @8 ohms
(both channels operating ) 400/400 watts @4 ohms

Harmonic Distortion: Less Than .15% (20Hz-5kHz)

(THD) @ 250 watts Less Than .5% (5kHz-10kHz)

IM Distortion: Less Than .15%

(4:1 60-7kHz) 150 watts

Frequency Response: 20Hz-10kHz ±.25dB

10kHz-15kHz ±.7dB
15kHz-20kHz ±1dB

Signal to Noise Ratio: -100dB ≤.5mV across 8Ω at zero volume

(unweighted)

Load Impedance: 4 ohms or higher

Input Sensitivity: 1.5 Vrms for 250 watts output into 8 ohms

Input Impedance: 50,000 ohms or higher

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 SAFETY INFORMATION

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. 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 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.

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 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 unpro-
tected devices into materials such as plastic, polystyrene foam, clear plastic bags, bubble
wrap or plastic trays.

General Description

The 1801 and 1800 are Integral Design™ Power Amplifiers with all Silicon Solid-State Circuitry
using 14 power transistors per channel. Capable of complete stability with all loudspeaker
loads regardless of capacitive or inductive character. They employ fast acting electronic pro-
tection circuits for current limiting. They use computer grade capacitors throughout the power
supply, along with a 2.0kW power transformer and 1300 sq. inches of heat sink area. They also
have a power monitor display using a light emitting diode array and in the case of the 1801
signal meters as well.

CAUTION: THE BOSE® 1801/1800 POWER AMPLIFIERS CONTAIN NO USER-SERVICE-

ABLE PARTS. TO PREVENT WARRANTY INFRACTIONS, REFER SERVICE TO WAR-
RANTY SERVICE STATIONS OR FACTORY SERVICE.

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 DISASSEMBLY/ASSEMBLY PROCEDURES
1801 Power Amplifier
Note: Refer to Figure 1 for the following 4.3 Connect the wire harness, thermal
procedures. cutout wires, and the input cable to the
PCB.
1. Top Cover Removal
5. Front Panel Removal
1.1 Remove the two screws that secure
5.1 Perform procedure 1.
the top cover at the rear of the unit. Loosen
the two screws located on each side of the
5.2 Remove the nut securing the top of the
unit towards the front.
front panel. The nut is located on the inside
of the front chassis beside the thermal
1.2 Slide the top cover towards the rear of
cutout indicator.
the unit and lift the cover off the unit.
5.3 Remove the knobs on the controls and
2. Top Cover Replacement
remove the two shaft nuts holding the front
panel in place.
2.1 Slide the top cover onto the unit while
making sure the screws on the side of the
6. Front Panel Replacement
unit are lining up with the slots in the top
cover.
6.1 Align the front panel over the controls
and secure it in place.
2.2 Secure the top cover to the unit.
6.2 Secure the top of the front panel and
3. Amplifier PCB Removal
replace the knobs.
3.1 Perform procedure 1.
6.3 Perform procedure 2.
3.2 Disconnect the wire harness, the two
7. Front Chassis Assembly Removal
wires connected to the thermal cutout, and
the input cable going to the PCB.
7.1 Perform procedure 5.
3.3 Remove the six screws (2B) located on
7.2 Locate and remove the four screws
the side of the unit between the heat sink
that secure the front assembly to the
fins (see Figure 2).
chassis.
3.4 Carefully pry the PCB inward towards
7.3 Push down on the top of the front
the power transformer (the PCB is stuck to
assembly to release the bottom of the
the chassis by the heat sinking compound)
assembly and pull the assembly towards
and lift the board out of the unit.
you.
4. Amplifier PCB Replacement
8. Front Chassis Assembly Replacement
4.1 Slide the PCB into place. Be sure there
8.1 While pushing down on the front
is sufficient heat sink compound on the
assembly slide the assembly in towards the
PCB's heat sink.
unit.
4.2 Align the six screws that secure the
8.2 Pull up on the front assembly to align
PCB into place and secure the PCB to the
the screw holes with the unit and secure
chassis.
the assembly in place.

8.3 Perform procedure 6.

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 DISASSEMBLY/ASSEMBLY PROCEDURES
1801 Power Amplifier
Note: Refer to Figure 5 for the following 12.2 Place the meter lamp housing over
procedures. the meters and secure it to the front assem-
9. LED PCB Removal bly.

9.1 Perform procedure 7. 12.3 Perform procedure 8.

9.2 Unsolder the wires to the LED PCB 13. Front Panel Controls Removal
and make a note of the wiring configura-
tion. 13.1 Perform procedure 7.

9.3 Remove the center nut located on 13.2 Locate the control or switch you want
each side on the LED lamp housing. to replace and unsolder the wires and
components on that control or switch.
9.4 Lift the LED assembly out from the
front chassis. 13.3 Remove the shaft nut holding the
control or switch to the front assembly and
9.5 Disassemble the LED assembly to gain remove it.
access to the PCB.
Note: Remember how the lamp housing 14. Front Panel Controls Replacement
spacers are placed.
14.1 Place the new control or switch into
10. LED PCB Replacement the front assembly and secure it in place.

10.1 After reassembling the LED assem- 14.2 Resolder the wires and/ or compo-
bly, place it onto the front panel assembly nents to the control or switch.
and secure it in place.
14.3 Perform procedure 8.
10.2 Resolder the wires to the PCB.
15. Lamp Removal
10.3 Perform procedure 8.
15.1 Perform procedure 7.
11. Meter Assembly Removal
15.2 Using a flat blade screwdriver, pry
11.1 Perform procedure 7. under the edge of the socket and lift the
socket out.
11.2 Remove the three nuts holding the
meter lamp housing assembly to the front 16. Lamp Replacement
panel assembly.
16.1 Replace the defective lamp.
11.3 Remove the two nuts holding the
wires to the meter you want to replace and 16.2 Place the lamp socket back into the
remove the meter. lamp housing.

12. Meter Assembly Replacement 16.3 Perform procedure 8.

12.1 Place the new meter on to the front Note: It may be necessary to remove the
assembly. Connect the wires going to the
LED PCB Assembly to replace the lamps
meter.
see procedure 9.

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 DISASSEMBLY/ASSEMBLY PROCEDURES
1800 Power Amplifier
Note: Refer to Figure 1 for the following 5. Front Panel Removal
procedures.
5.1 Perform procedure 1.
1. Top Cover Removal
5.2 Locate and remove the eight screws
1.1 Remove the four screws that secure holding the front panel to the chassis. Four
the top cover to the unit. of the screws are located just inside the
two handles and the other four are the
1.2 Slide the top cover towards the back of larger screws on the front panel.
the unit and lift it off.
5.3 Using the handles pull the front panel
2. Top Cover Replacement away from the chassis enough to access
the gain controls and LED PCB.
2.1 Place the top cover on to the unit and
slide it under the front panel lip. 6. Front Panel Replacement

2.2 Secure the top cover to the unit. 6.1 Slide the front panel into place. Be
careful not to pinch the wiring harness at
3. Amplifier PCB Removal the bottom of the front panel between it
and the chassis.
3.1 Perform procedure 1.
6.2 Align the holes in the front panel with
3.2 Disconnect the wire harness, input the chassis, place the screws into their
cable, and the two wires going to the location by hand and then tighten with a
thermal cutout. screwdriver.
Note: While tightening the screws lift up
3.3 Remove the six screws (2B) located on on the top lip of the panel to provide
the side of the unit between the heat sink enough room to slide the top cover under
fins (see Figure 2). the lip.

3.4 Carefully pry the PCB inward towards 7. LED PCB Removal
the power transformer (the PCB is stuck to
the chassis by the heat sinking compound) 7.1 Perform procedure 5.
and lift the board out of the unit.
7.2 Remove the two screws that secure
4. Amplifier PCB Replacement the PCB to the front panel.

4.1 Slide the PCB into place. Be sure there 7.3 Unsolder the wires at the LED PCB,
is sufficient heat sinking compound on the make a note of the wiring configuration,
PCB's heat sink. and remove the board from the unit.

4.2 Align the six screws that secure the 8. LED PCB Replacement
PCB into place and secure the PCB to the
chassis. 8.1 Place the LED PCB into place on the
front panel.
4.3 Connect the wire harness, thermal
cutout wires, and the input cable to the 8.2 Secure the PCB to the front panel.
PCB.
8.3 Resolder the wires to the LED PCB.

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 DISASSEMBLY/ASSEMBLY PROCEDURES
1800 Power Amplifier
Note: Refer to Figures 3, and 4 for the Note: Refer to Figure 6 for the following
following procedures. procedures.

9. Gain Control Removal 13. Rear Panel Removal

9.1 Perform procedure 5. 13.1 Perform procedure 1.

9.2 Remove the gain control knobs. 13.2 Locate and remove the four screws
securing the rear panel and the rear panel
9.3 Unsolder the capacitor lead and wires bracket to the unit.
from the control. Note: One of the screws holds the ground
wires to the chassis. Take care not to lose
9.4 Remove the nut that secures the the nuts that secure this screw and the
control to the front panel and remove the wires.
control.
14. Rear Panel Replacement
10. Gain Control Replacement
14.1 Align the rear panel with the chassis.
10.1 Place the new control into the front
panel and secure it into place. 14.2 Secure the rear panel to the chassis.
Be sure to use the rear panel bracket on
10.2 Resolder the capacitor lead and the the bottom of the panel.
wires to the terminals on the gain control.
14.3 Secure the ground wires to the
10.3 Perform procedure 6. chassis.

11. Power Switch Removal 14.4 Perform procedure 2.

11.1 Perform procedure 5.

11.2 Remove the wires on the rear of the

power switch.

11.3 Remove the nut securing the switch

to the front panel and remove the switch.

12. Power Switch Replacement

12.1 Place the new power switch into the

front panel and secure it in place.

12.2 Reconnect the wires on the rear of

the switch.

12.3 Perform procedure 6.

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 TEST PROCEDURES
1. Bias Adjustment Setup and Procedure 4. Power Output Procedure

1.1 Locate the -85V negative terminal 4.1 Connect an 8 ohm, 250 Watt load to
found on the capacitor (C4). See Figure 1 the output.
for the location of C4.
4.2 Apply a 1.75Vrms, 1kHz signal to the
Note: The 1801 and very early 1800's had input.
two lugs on the caps. One with two or three
wires and one single wire. The later pro- 4.3 Turn the gain controls up to the point
duction 1800 had three lugs on the capaci- where the clipping LED's just begin to
tor. Either way the lug with the two or three light up and check the output for 250
wires is the lug to disconnect from the watts.
capacitor. All other lugs remain.
4.4 Repeat the steps above for a 4 ohm
1.2 Remove the lug with two or three wires load. The output measurement should be
connected to it. 400 watts.

1.3 Connect a 0-200mA meter between 5. Harmonic Distortion Procedure

the disconnected lug and the - terminal on
the capacitor C4. 5.1 With the unit connected as in proce-
dure 3, turn the gains up to just before
1.4 Disconnect the PCB that is not being clipping and check the distortion at the
tested by unplugging the multiple pin frequencies of 20Hz, 5kHz, and 10kHz.
connector.
5.2 The distortion limits are ≤.15% from
1.5 Turn the amplifier on with no input 20Hz to 5kHz and ≤.5% from 5kHz to
signal applied and adjust the bias pot (R13) 10kHz.
for 90mA with the board cold.
6. Thermal Cutoff Procedure
Note: The PCB must be removed from
the chassis for the bias to be adjusted. 6.1 Apply a signal to the unit with the
outputs loaded ( 8 or 4 ohms ). Short one
2. Frequency Response Procedure channel at a time until the unit goes into
thermal cutoff. The thermal indicator should
2.1 Apply a 1Vrms, 1kHz signal to the turn on and the output of the unit should be
input. off.

2.2 Reference a dB meter to the output. 6.2 Disconnect the short from the output.
Wait until the unit comes out of thermal
2.3 Check the response from 20Hz to cutoff. You can speed this process by
20kHz. The response should not exceed ±1 cooling the PCB with a fan.
dB. Refer to the response specification on
page 2. 6.3 Once the unit is cooled apply a signal
to the channel you had shorted to check to
3. DC Offset Procedure see if its operational.

3.1 With no signal applied measure the DC 6.4 Apply a signal to the other channel and
offset at the output. It should measure short the output. Wait for the thermal
250mV or less. indicator to come on then remove the short
and cool the PCB.

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 Figure 1. 1801 Component Location

Figure 2. 1801 Side View

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 Figure 3. 1800 Front Panel

Figure 4. 1800 Rear View of Front Panel

Figure 5. 1801 Rear View of Front Panel

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 Figure 6. 1800 Rear Panel

Figure 7. 1801 Rear Panel

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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 reference designators in bold are located on the LED PCB.

3. This part is not located on the PCB'S.

4. The reference designators marked with a ‡ symbol are located on the Front Panel.

5. The part numbers listed with SIM are selected components and may not be directly inter-
changeable with standard available parts.

6. This part is located on the amplifier PCB.

7. This part is used on the 1801 Power Amplifier.

8. This part is used on the 1800 Power Amplifier.

9. Items marked with a ¥ symbol are not shown in the exploded views.

Figure 8. 1801 Front Panel

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 PART LIST
Main Part List (per figures 1-7)
Item Description Part Note
Number Number
A1 Preload Network 102666 6
RT-1, RT-2 Thermal Cut-Out 102440 6
¥ RCA Jack 102784 6, 9
Q10-23 Screw, 6/32 x 1/2 Stainless Steel 106348 6
Q10-23 Washer 103032 6
Q10-23 Plastic Insulator 102901 6
Q10-23 Nut, Brass, 6/32 x 5/16 x 1/8 103016 6
Q4, 5 Heat Sink Assy 102571 6
¥ Top Wiring Harness 102929-1 1, 7, 9
¥ Bottom Wiring Harness 103281-1 1, 7, 9
¥ Top Wiring Harness 103365 1, 8, 9
¥ Bottom Wiring Harness 103366 1, 8, 9
¥ Audio Cable 102838 9
S1 Toggle Switch, ON/OFF 103291 8
S1 Switch, ON/OFF 102740 7
S2 Input Switch 102576 7
S3 Speaker Switch 103400 7
J3, 4 (J5, 6 1801 ) Phone Jack 102704
R5, 6 Gain Control, 100kΩ 102406 7
R5, 6 Gain Control, 100kΩ 103260 8
1 Indicator Lens, White 103479-1
2 Indicator Lens, Red 103479-0
3 Lens Housing 103478
4 Front Handle 121914 8
5 Knob 128907 7
5 Knob 121911 8
M1, 2 VU Meters 102570 7
B1-4 Meter Lamps 103063 7
B5, 6, 7 L.E.D / Bose® Logo Lamp 1847 102580 7
B8 Thermal Cutout Indicator 102582 7
K1 Start-up Relay 102818
6 Accy Outlet 107558
7 Line Cord 103441
T1 Transformer 102434 1, 7
T1 Transformer (110v) 110185 1
T1 Transformer (220v) 112669 1

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 PART LIST
Main Part List (per figures 1-7)
Item Description Part Note
Number Number
8 Rubber Foot 121929
F1 Fuse (110v)15A, 1 1/4 x 1/4Slo-Blo 103608
F1 Fuse (220v) 8A, 5 x 20mm 108190-800
F1 Fuse (220v) 7A, 1 1/4 x 1/4Slo-Blo 103609
¥ Fuse Cap for 1 1/4 x 1/4 109484 9
¥ Fuse Cap for 5 x 20mm 109493 9
9 Front Panel Assy 103380 1, 7
10 Front Panel Assy 121910 1, 8
11¥ Rear Panel Assy 103282 1, 7, 9
12 Rear Panel Assy 103266 1, 8
13 Amp PCB Complete 102735-1 1
14 L.E.D Board Complete 102751 1
Carton and Fillers 103268
15 Heat Sink Side 102536 1
16 Heat Sink Corner 102474 1
17 Top Cover 102544 1, 7
18 Top Cover 121930 1, 8
19 Screw Heat Sink 103041
¥ Accessory Kit 102745 1, 7, 9
¥ Accessory Kit 103361 1, 8, 9
20 Black Binding Post 109068-0
21 Red Binding Post 109068-2
22 Blue Binding Post 109068-6
23 Black Binding Post Base 109069-0
24 Fuse Holder 109485
25 Strain Relief 102708

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 PART LIST
Resistors
Reference Description Part Note
Designator Number
R1-4 1MΩ, 1/2W, 10% 102944-105 3
R2 8.2kΩ, 1/2W, 10% 104064-822
R3 3kΩ, 2W, 10% 108676-302
R9, 17 6.19Ω, 1/4W, 1% 104095-6191
R11 1.5kΩ, 1/4W, 1% 104095-1501
R12, 51, 53 340Ω, 1/4W, 1% 104095-3400
R13 100Ω, Bias Pot 102832
R18, 20, 48 23.7kΩ, 1/4W, 1% 104095-2372
R25, 26 182Ω, 1/4W, 1% 104095-1820
R31-36, 41-46 0.8Ω, Wirewound, 3W, 5% 102394
R37-39 0.4Ω, Wirewound, 6W, 5% 102395
R47 4.7Ω, 2W, 5% 102393
R50 470Ω, 1/2W, 5% 102942-471
R52, 54 10kΩ, 1/4W, 1% 104095-1002
R55, 57 100kΩ, 1/4W, 1% 104095-1003
R56 680Ω, 1/2W, 5% 102942-681
R1,3,101,103 5.1kΩ, 1W, 5% 104064-512 2
R2,4,10,13,16,19 150Ω 1/2W, 5% 102942-151
102,104,107,110 2
113,116,119
R5,105 3.6kΩ, 1W, 5% 104064-362 2
R6,9,106,109 2kΩ, 1/2W, 5% 102942-202 2
R8,108 8.2kΩ, 1W, 5% 104064-822 2
R11,111 12kΩ, 1/2W, 5% 102942-123 2
R12,15,18,112, 1kΩ, 1/2W, 5% 102942-102
115,118 2
R14,114 24kΩ, 1/2W, 5% 102942-243 2
R17,117 43kΩ, 1/2W, 5% 102942-433 2
R20,120 15kΩ, 1/2W, 5% 102942-153 2
R21,121 120Ω, 1/2W, 5% 102942-121 2
R22,122 18kΩ, 1/2W, 5% 102942-183 2

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 PART LIST
Capacitors
Reference Description Part Note
Designator Number
C1‡, 2‡ 1uF, Mylar, 50v, 10% 102751 4
C1, 14, 15 .1uF, Electrolytic, 100v, 10%, NP 102403
C1,101 100uF Electrolytic, 3v 102836 2
C2, 3 30uF Electrolytic, 100v 102405
C3, 4 14,000uF, Electrolytic, 100v 102438 3
C5 18,000uF, Electrolytic, 10v 104229 3
C5, 16 27pF, Ceramic Disc, 25v, 10% 102397
C6, 7, 10, 11 .01uF, Ceramic Disc, 25v, 10% 102399
C8 200pF, Ceramic Disc, 200v, 10% 102400
C9 300pF, Ceramic Disc, 200v, 10% 102396
C12, 13, 17 1000pF, Ceramic Disc, 200v, 10% 102453

Diodes and Transistors

Reference Description Part Note
Designator Number
D1-4 Bridge Rectifier 102578
D5-8 Diodes 102422
CR1-4, 7, 16, 17 Diode 1N4148 116997
CR10-17,110-117 2
CR1-9,101-109 L.E.D Diode 106864 2
CR5, 18, 19 Diode SIM 1N3070 102411
CR6, 15 Diode 1N5425, Zener, 15V, 1/2w 102423
CR8-14, 20, 21 Diode SIM 1N4003 102422
Q1 SIM MM-4001 102425 5
Q2, 8 SIM 2N3906 102426 5
Q2,102 2
Q3 SIM 2N6175 102427 5
Q4 SIM 2N2219 102428 5
Q5 SIM 2N5415 102429 5
Q6 SIM 2N3584 102430 5
Q7, 24, 25 SIM 2N3904 102432 5
Q1,3-10,101,103-
110 2
Q9 SIM 2N6211 102431 5
Q10-23 MJ15011 117579
U1 Integrated Circuit, MC1556G 102409

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 Bridge Rectifier

Turn On Relay

Figure 9. 1801/1800 Block Diagram

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 Figure 10. LED PCB Layout

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 Figure 11. LED PCB Schematic Diagram

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Notes:
1. See Bias Adjustment Procedure.
2. U1 input (pin 2) virtual ground, output test point 8 (pin 6) 275mV.
3. Early production units replace R28 with capacitor C15 (0.1uF) found
in either side of the pc board.
4. All resistors are 1/2 watt 5% unless otherwise specified.
5. All capacitor in uF unless otherwise specified.

Figure 12. Amplifier Schematic Diagram

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 Figure 13. Amplifier PCB Layout

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 TROUBLESHOOTING GUIDE
SYMPTOM POSSIBLE CAUSE

1. DC Offset:
≤2v Defective U1
Defective Q1

≥2v Defective U1 Test point "A" polarity

Defective CR1, 2, 6, 15 the same as DC offset
Open ground at the RCA (see Figure 11)
input jack
Defective Q1-8, Q24 Test point "A" polarity
Defective CR16, 17 opposite to the DC offset
(see Figure 11)

2. High Current: Short between transistor Trouble shoot (by removing

and heat coupler collector screws) in this
Shorted driver or output sequence.
transistor
Negative: Q9, 11, 23, 21,
22, 19, 20, 18

Positive: Q6, 10, 17, 16,

14, 13, 12, 15
3. Oscillation:

Unloaded Defective C5
Defective Q6, Q9
Defective CR8

Loaded Open C4, 5, 9, 11

Defective R24, 29, 30,
51, 52

4. Excessive Noise: Defective U1, Q1

Defective R57, 58

5. No Bias Adjustment: Defective Q4, 6, 7, 9

Open R11, 12, 13

6. Incorrect Frequency
Response: Defective C5, C8
Shorted Mica Insulator Q3

7. Excessive Distortion: Defective Q7, Q8, Q25

Defective CR18, 19
Defective CR5 ( at full
output only)

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 VOLTAGE CONVERSION INSTRUCTIONS
1. Perform Top Cover removal procedures for the model amplifier your going to convert.

2. Refer to the figures below for the voltage conversion being performed.

3. On the 1801 when converting to 110 volts remove the in-line resistor found wired to the
thermal cutoff indicator. Connect the wire directly. For 220 voltage conversion connect a
56k ohm 1/2 Watt resistor directly to the thermal cutoff indicator terminal.

4. Use an MDL 10 amp fuse for 110 volt operation.

5. Use an MDL 5 amp fuse for 220 volt operation.

NOTE: FOR 220 VOLT AC USERS ONLY

For 110 volt operation of the accessory outlet, move the wire labeled "TO RECEPTACLE"
from transformer connector #4 to connector #2. The amplifier will operate on 220 volts
and provide 110 volts to the accessory outlet (up to a maximum of 3 amps).

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 SERVICE BULLETIN
Subject: Interchangeability of repaired amplifier PCB. Date: 09/19/1977
Torroidal Power Transformer.
1800 Amplifier used with a TC-18 Transit Case. Bulletin #13

Remarks:
The 1801 power amplifier board ( part # 102735 ) will no longer be shipped as a standard
repair part. Instead, a universal replacement board ( part # 102735-1 ) with a special thermo-
static clip connection allowing the use of this board in the 1801 and early production 1800 wire
harness assembly.

In the case of the 1801, amplifier boards may be intermixed with no difficulty, using the clip
connection.

In the case of the 1800, amplifier boards may be intermixed below serial #750. However, for
serial numbers above 750, use of the larger heat sink version (102735-1) is required.

When replacing amplifier boards in either unit, be certain to use additional thermal grease and
to tighten the screws holding the board to the chassis.

The 1800/1801 amplifiers are now using a torroidal power transformer that reduces the unit's
overall weight by 20 Lbs. The new transformer, ( P/N 107968 ) is found in 1800 amplifiers ( S/N
1630 and above ) and in 1801 amplifiers ( S/N 6838 and above ). Connections for the trans-
former are the same as indicated in the Service Manual for both units.

The 1800 power amplifier, when used with the TC-18 transit case, should be inspected periodi-
cally for dirt and dust accumulation on the heat sink surfaces. Any accumulation should be
removed as this significantly reduces the amplifier's ability to dissipate heat and increases the
likelihood of thermal overload.

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 SERVICE BULLETIN

Subject: Resistor Failure Date: 09/19/1977

Bulletin #13A
Remarks:
We have found that the resistor R3 on the 1801/1800 amplifier PCB's have shown a higher
failure rate than normal. Studies reveal that the resistor normally runs at about 150-170°F. The
etch layout at R3 is not sufficient to provide adequate heat sink for this component, and the
resistor eventually changes value due to the heat.

This changing value causes the resistor, capacitor C2, and the zener diode CR15, to fail. The
symmetrical circuit, R2, C2, and CR6 all have sufficient heat sinking capability on the etch
layout and does not cause failures.

To improve the reliability of the boards, R3 should be changed from a carbon resistor to a
ceramic resistor of the same value. The ceramic resistor should be elevated slightly above the
PCB surface to provide adequate air ventilation for self cooling purposes. The new ceramic
resistor P/N is 108676-302.

In addition, R2 should also be changed to a new value. The resistor will be changed from 3kΩ
to 8.2kΩ, P/N 104064-822. This resistor is carbon, and due to the etch layout, need not be
elevated.

This modification must be preformed on all PCB's brought in for repair, regardless of the actual
failure.

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 SERVICE BULLETIN
Subject: Thermal Improvement Date 10/05/1979
Bulletin #17
Remarks:
I'm pleased to inform you that we have developed a method for improving the thermal stability
of the 1800 amplifier, which may have been a problem to you during the last several months.
This problem was caused by a change we were forced to make when RCA discontinued the
manufacture of the transistor we had been using as Q3 on the 1800 PCB's.

The following change should be made on 1800 PCB,s which have the new Q3 ( MMPS U10 ).

1. Change R13, the bias pot (P/N 102832), to a new one which has not been sealed with
glyptol. This will allow you to adjust the bias current later.

2. Change R11 (P/N 102977-1501) from 1.5kΩ to 1.8kΩ (P/N 107170-182).

3. Apply a piece of Mylar insulating tape over the small (3/4" x 1/4") vertical surface of the heat
coupler bracket that is immediately above and parallel to C12.

4. Apply a small blob of thermal grease to the Mylar tape.

5. Obtain a 10kΩ thermistor (P/N 111153) and place insulating tubing over the leads, leaving
them about 1 inch long.

6. Solder the thermistor across (in parallel) the new R11.

7. Place the body of the thermistor against the blob of thermal grease applied in step 4.

8. Obtain a thin piece of polypropylene or other springy plastic and cut it to about 3/8" x 3/4".
Punch a small hole in one end of it and fasten it to the heat bracket using the screw that
mounts Q3 to the bracket. The tension of the bent piece of plastic will keep the thermistor
pressed into the thermal grease.

9. Adjust the bias current to 90ma according to the service manual.

NOTE: This change will be made on all future production units of the 1800 amplifier.

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 SERVICE BULLETIN
Subject: Output Transistors Date: 10/13/1980
Bulletin # Pro-81-001
Remarks:
Due to supply demands, Bose® Corporation has changed the output transistors on the PM-2
and the 1800 amplifier boards currently being produced. The transistors have been change
from Bose P/N 102433 (2N5840) to P/N 117579 ( Motorola MJ15011). The new output transis-
tors are not compatible with the original 102433 transistors. If you service an 1800 power
amplifier or PM-2 mixer, check the serial numbers on the printed circuit board and the P/N on
the output transistors to see which output device is being used. Below is a list of the approxi-
mate serial number break for the newer P/N 117579 transistors.

PM-2 Boards: Approximately 30800 and above

1800 Boards: Approximately 30800 and above

PM-1 Boards: All have P/N 102433

1801 Boards: All have P/N 102433

When replacing output transistors, you must use the correct replacement device. Older units
with P/N 102433 on the output transistors must be replaced with 102433 (2N5840) transistors.
Units with output transistors with P/N 117579 must be replaced with 117579 (MJ15011) transis-
tors.

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 29
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 ®

Bose Model 1801/1800

Power Amplifiers

©
1997 Bose Corporation Service Manual
Part Number 192527 REV 01
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 SPECIFICATIONS AND FEATURES SUBJECT TO CHANGE WITHOUT NOTICE

Bose Corporation
The Mountain
Framingham Massachusetts USA 01701
P/N 192527 REV. 01 06/97 FOR TECHNICAL ASSISTANCE OR PART ORDERS, CALL 1-800-367-4008

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