BOSE AM-3P II Schematic

Table of Contents

Note: This service manual has been updated with information from service manual supplement 175032-S2. This supplement affects part number for R146 and R246 as used on the amplifier PCB. Refer to 175032-S2 for more information.

SAFETY INFORMATION...................................................................................................... 2

ELECTROSTATIC DISCHARGE SENSITIVE (ESDS) DEVICE HANDLING....................... 3

SPECIFICATIONS ................................................................................................................4

Figure 1. Bass Channel Frequency Response Curve ................................................ 5

Figure 2. Left/Right Channel Frequency Response Curve ........................................5

Figure 3. AM-3P II Amplifier PCB Assembly Block Diagram...................................... 6

Figure 4. AM-3P II Equalizer PCB Assembly Block Diagram ..................................... 6

AM-3P II THEORY OF OPERATION .................................................................................... 7

AM-3P II DISASSEMBLY/ ASSEMBLY PROCEDURES ................................................... 13

AM-3P II TEST PROCEDURES ......................................................................................... 18

Figure 5. 120/240V Transformer Schematic .............................................................. 22

Integrated Circuit Diagrams .............................................................................................23

PART LISTS AND EXPLODED VIEWS .............................................................................26

AM-3P II Bass Module Part List .................................................................................. 27

AM-3P II Satellite Part List .......................................................................................... 28

Figure 6. AM-3P II Bass Module Exploded View ....................................................... 29

Figure 7. Woofer Location in Module......................................................................... 30

Figure 8. Satellite Exploded View............................................................................... 30

AM-3P II Packaging List .............................................................................................. 31

Figure 9. AM-3P II Packaging Exploded View ........................................................... 33

AM-3P II Main PCB Assembly Part List...................................................................... 34

AM-3P II Amplifier PCB Assembly Part List ..............................................................39

SCHEMATICS AND PCB LAYOUTS.................................................................................. 42

CAUTION: THE ACOUSTIMASS®-3 POWERED SPEAKER 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 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.

CORPORATION WHICH IS BEING FURNISHED ONLY FOR

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 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 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 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 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.

SPECIFICATIONS

Dimensions Module: 7.75"H x 18.5"W x 8.5"D (20x47x22 cm)

Satellite: 3"H x 3"W x 4.75"D (7.9x7.9x12.1 cm)

Weight Module: 21 lbs. (9.5 kg.)

Satellite: 1 lbs. (0.45 kg.)

Packed System: 27 lbs. (12.3 kg.)

Driver 1-5-1/4" Woofer Complement 2-2-1/4" Twiddlers™

Finish Module: Black or white, scratch-resistant, satin-finished

vinyl

Satellites: Black or white, painted polymer finish

PERFORMANCE SPECIFICATIONS

Input Power 115/230VAC, 175 Watts, 50/60 Hz Amplifier Power Woofer (single): 50 watts into 5Ω resistive load,

≤0.2% THD, from 40-200 Hz

Satellites (each): 20 watts into 4Ω resistive load,

≤0.2% THD, from 200Hz-15kHz

Input Impedance AM-3P II System: 5.9kΩ ± 4%

Multimedia System: 26kΩ

Speaker Satellites: 4Ω Impedance Woofer: 5Ω

Distortion @ 1W <0.1% THD (all channels) Output Noise <180µVrms A weighted for L/R channels Output Hum <500µVrms Unweighted for bass channel Channel @1kHz >40 dB

Separation @10 kHz >30 dB Port Tuning Small Chamber: 110 Hz

Frequency Large Chamber: 43 Hz Input Sensitivity AM-3P II: 0.6 Vrms @1kHz produces rated power in L/R

Multimedia: 0.2 Vrms channel outputs (at full volume)

Turn-On Delay 80ms ± 40 ms

(Auto)

Frequency Response Curves

AM-3P II bass channel frequency response with bass control at min., max. and flat positions for 30 and 200 mVrms input level. A boost occurs at 55Hz for low input levels-i.e.-30mV. The gain measurements in this graph should be referenced to the input level.

Figure 1. Bass Channel Frequency Response Curve

AM-3P II left/right channel frequency response with treble control at min., max. and flat positions. The gain measurements in this graph should be referenced to the input level.

Figure 2. Left/Right Channel Frequency Response Curve

BLOCK DIAGRAMS

Figure 3. AM-3P II Amplifier PCB Assembly Block Diagram

Figure 4. AM-3P II Main PCB Assembly Block Diagram

AM-3P II THEORY OF OPERATION

NOTE: The following discussion references the AM-3P II/Multimedia Main and Amplifier PCB schematics, and block diagrams. The block diagrams, Figures 3 and 4, can be found on page 6 and the schematics are located in the back of this service manual.

GENERAL

The AM-3P II powered Acoustimass Home Audio and Multimedia. Both variations can be used with the Bose

loudspeaker system is manufactured in two variations:

Lifestyle® Music System or other sources that have line-level outputs. The multimedia variation was designed specifically for computer sound amplification. The basic differences of the multimedia are as follows:

• 10dB higher gain to accommodate the lower output level of computer sound cards.

• Higher input impedance for compatibility with most industry standard audio equipment.

• RCA input jacks allow mixing of two separate stereo signals (Source 1 and Source 2 inputs).

The AM-3P II is based acoustically on the AM-3P Series I Acoustimass

powered loudspeaker system. The distinguishing difference between Series I and Series II is the change to a new satellite enclosure (AM-4), and equalizer PCB assembly designed to compensate for the acoustic differences of this new enclosure. Listed below are some of the features of the AM-3P II.

• Automatic turn-on/turn-off mute of the amplifier output stage

• Automatic (BOSE

patented) dynamic equalization

• Bi-amplification for better power distribution to speakers

• Active equalization for smoother frequency response

• Amplifier short-circuit and DC offset fault protection

• Local volume/sensitivity control

• Bass/treble room compensation controls

• Differential input stage (to reject hum)

• Dynamic compressor to prevent amplifier output overload distortion

BLOCK DIAGRAM DESCRIPTION

NOTE: In the discussion of L/R (left/right) channels, only the right channel is discussed. The

left channel operation is identical.

1. Power Supply

A single, universal, 115/230V EI core power transformer is used to power the system. It has been specially designed for minimum magnetic flux leakage and stand-by power consumption. The transformer primary remains energized (always on) except when the power switch is in the off position.

The two primary windings of the transformer are wired in series for 230V operation, and in parallel for 115V operation, depending on the position of the customer accessible voltage select switch. If the system is accidentally energized at 230V with the switch in the 115V position, the replaceable fuse (F1 located on the Main PCB assembly), will open the circuit within two minutes. This will be the only damage to the system.

A non-serviceable thermal fuse is located inside the transformer to limit the maximum temperature to 145 °C under abnormal conditions. However, in most cases the external fuse (F1) should fail before the internal transformer thermal fuse. The thermal fuse can be checked by measuring the continuity between pins 1 and 4 (black and white wire) of the primary connector. This connector is located on the Main PCB.

2. Differential Input Stage

Audio input applied at the phono jack (J8) connects directly to the right (left) differential amplifier buffer. This stage accomplishes several functions:

• Provides rejection of common-mode interference (such as hum) that might be picked up by the long audio cable between the AM-3P II and Lifestyle

music center

• Provides input overload and ESD protection through diodes (D101-D104)

• Removes radio frequency interference through C103, C125, C127

• Provides DC blockage by C101,102

• Provides a 6 dB gain through op-amp U101.

3. Compressor/Treble Stage U102 (pins 1, 2, 3) with potentiometer VR2 at the center position, operates as a conventional

inverting operational amplifier stage with a gain of 6 dB. However, when voltage overload is present at the speaker outputs, transistor array U1 (pins 1, 2, 3) receives a turn-on signal from the compressor detect stage. Under this condition, the transistor acts as a variable resistor to ground, and with R107, forms a resistor divider network that attenuates the audio signal. The amount of attenuation and timing action is carefully controlled by the compressor detect stage (to be discussed later).

Potentiometer VR2 adjusts the amount of treble boost or cut. In the full counterclockwise position, the wiper (pin 4) shorts to pin 1. The maximum boost and cut frequency response graph is shown in Figure 2 on page 5.

4. High Frequency (HF) Equalization

High frequency equalization and crossover is achieved through three cascaded active EQ stages. These stages consist of U103, U104 and U105. The purpose of equalization is twofold:

• It provides very sharp low frequency attenuation below 200 Hz (the crossover frequency) to prevent overload of the L/R speakers

• It provides finely tailored correction in the speaker passband so that overall frequency response of the system is acoustically correct

The U103 stage is a combination 2

order 200 Hz high-pass filter and 5 dB 2 kHz dip notch filter. The U104 stage provides the 5 dB peak at 200 Hz and the sharp band-reject between 100 and 200 Hz. Finally, the U105 stage is a combination 2

order 20 kHz low-pass filter and 2 dB 350

Hz notch filter.

5. Bass Control

The bass channel signal is derived from the sum of the left and right channels through resistors R129 and R229 and through inverting op-amp summer U2. Potentiometer VR3 simply adjusts the gain of the stage between -6 dB to +6 dB. In the flat (center) position of the control ,the gain is 0 dB. Adjusting the bass by varying the gain of the overall bass channel has been determined to be acoustically appropriate to compensate for various placement options of the bass module.

6. Automatic Dynamic Loudness

In order to compensate for the ear’s loss of bass response at low listening levels, a BOSE patented (4,739,513) automatic loudness circuit is employed. This circuit automatically senses the volume level of the incoming audio signal and properly adjusts the amount of low frequency bass boost. When the volume level is high, the frequency response of the circuit is flat. When the volume level is decreased (at the music center), the low frequency gain is increased in the region between 50 and 150 Hz (see the bass channel frequency response graph, Figure 1 on page 5). This loudness contour, and the time constants associated with it, have been precisely determined through psycho-acoustic testing and should not be confused with other conventional loudness schemes.

Circuit operation is as follows: Left and right audio output at pins 7 and 1 of U101 are summed together by resistors R132 and R232. The AC signal at pin 3 of level detect op-amp U2 is negative-peak detected and is presented across emitter resistor R9. The peak detected signal has a (approximate) 4 second hold time and a 4 sec/10 dB release time constant which is developed within the feedback loop of U2 (pins 1, 2, 3). The voltage across R9 is converted to a current source through transistor Q3, and flows into pin 5 of transconductance amplifier U4. U4 is placed in the feedback loop of op-amp U3 to create an inverse voltage controlled bandpass stage such that increased current into pin 5 of U4 causes the gain of the bandpass stage to decrease. The 55 Hz bandpass filter consists of resistors R10, R11 and R15 and capacitors C6 and C7. At frequencies above 200 Hz, the stage acts as a unity gain follower (flat frequency response) through resistors R16, R17 and R18. The overall loudness contour response is visible at U3 pin 1.

7. Low Frequency (LF) Equalization

Low frequency bass channel equalization and crossover is accomplished in two active filter stages. The first stage consists of op-amp U3 (pin 5, 6, 7), capacitors C9 and C10 and resistors R19, R20, and R21. It creates the sharp band-reject attenuation below 50 Hz. The second stage consists of op-amp U5 (pin 1, 2, 3) capacitors C13 and C14, and resistors R24, R25, R26 and R27. It acts as a combination 2

order 50 Hz high-pass and 200 Hz low-pass filter. The combined response of these two stages is shown in the bass channel frequency response graph in Figure 1 on page 5.

8. Auto Turn-On/Off Mute

An improved version of auto turn-on/off is used in the AM-3P II. A separate 3.5 mm stereo mini-

jack (J7) is used to receive the turn-on signal from the serial data output of the Lifestyle

music center. When the 3.5 mm plug is inserted, the audio sense circuit is disabled and the amplifier outputs will only unmute if the DC control signal is present at J7 pin 3. This action occurs through the built-in DPDT switch in J7 which connects J7 pin 3 directly to the Q9 mute circuit. Therefore, the system is not subject to random false turn-on (from electrical noise, etc.) when used with the Lifestyle

When the AM-3P II is used with a source other than the Lifestyle

music center.

music center, the stereo miniplug is not inserted into the jack, and therefore mute transistor Q9 is directed to the output of the audio detect comparator U6 (pin 5, 6, 7). This comparator uses hysteresis to achieve a positive turn-on of at least 90 seconds before the system will revert to stand-by (mute) mode after removal of the audio signal.

9. Compressor Detect

The output of each left/right amplifier is half-wave detected through diodes D108 and 208. This voltage is divided down by R53 and R54 and presented at the emitter of Q12. Power supply voltage is similarly divided down by R50 and R51 and presented at the base of Q12. Diodes D13 and D14 simulate the saturation voltage drop that occurs in the power amp stage. Therefore, when the audio output of any amplifier comes within 2 volts of the instantaneous power supply voltage, Q12 will conduct. This signals the compressor (limiter) to act. Current from Q12 charges hold capacitor C35 and releases capacitor C36. Voltage at C35 is buffered by transistor U1 (pins 5, 6, 7) and decreased down to a logarithmic voltage by resistor R67 and diode U1 (pins 12,13,14). This voltage is then presented to the base of compressor transistors U1 (pins 1, 2, 3) and U1 (pins 8, 9, 10) which are described in the compressor section.

The DC control voltage present across capacitor C35 is derived through the use of an improved hold and release characteristic, resulting in lower compressor distortion. In conventional limiters, this DC control voltage is derived by a simple series diode and parallel RC network to ground. Unfortunately, for low frequency overload, this results in substantial ripple voltage present on the DC gain control voltage. This results in the all too common problem of mid-range voices or instruments being badly “modulated” by low frequency overload. This problem is solved by having two separate capacitors, one that “holds” the smooth DC voltage just long enough to prevent low frequency ripple (approximately 40ms) and the other (C36) which quickly releases the hold capacitor (through diode D17) at the proper time to maintain overall 100ms release time.

10. Power Amp (Amplifier PCB)

Four identical topology class B, power amplifier stages are used to create the three power amplifier channels. One each is used for the left and right power amplifiers (2 x 20W into 4 Ohm), and two are used in bridged mode for the bass channel to create 50W into 5 Ohm. Operation of the left channel (representative) is as follows:

A positive signal at op-amp input U106 pin 3 causes op-amp supply current to flow into pin 7 (and out through pin 6) through Q103. Q103 is used simply to buffer the +20V high voltage supply down to a safe +7.4V for the op-amp. This current also flows through R132 and diode D105. R132 and D105, together with driver transistor Q105 and R134 form a current mirror which multiplies the current through Q103 by the ratio R132/R134. This increased current flows through driver transistor Q105, and into the base of output transistor Q107. The hFE current gain of output transistor Q107 (about 100) provides final current amplification before reaching the speaker output.

The power amplifier topology is complementary. Therefore, operation of the amplifier on negative half cycles is identical to positive cycle operation, except for component reference designations.

11. Short-Circuit Protection

Left and right power amp stages have short circuit protection. This is necessary to prevent damage to the amplifier from customer misuse that might occur, for instance, if the customer were to accidentally short the speaker cable wires that connect to the cube speakers. If this happens, all three amplifiers will momentarily mute for about 3-4 seconds and continue to mute until the abnormal condition is removed.

Short circuit protection is achieved with the use of a .1

Ω resistor (R146 for left channel) in series

with each amplifier output. Under normal conditions, peak current to the 8 Ω speakers should never exceed 3.5A. If current flow momentarily exceeds 5.0A, then Q109 will conduct and trigger monostable multivibrator circuit U5 (pins 5, 6, 7) on the Main PCB. Pin 7 will go high (for about 3 seconds) and through diode D12 will trigger mute transistor Q10. Turn-on of Q10 causes all three amplifiers to mute. Referring to the left channel power amplifier, actual muting occurs by turning on transistors Q110, Q101, and Q102 which cause both driver transistors Q105 and Q106 to turn off. When the driver transistors are off, there can be no current flow through the output transistors, which results in no current flow to the speaker.

12. DC Offset Protection

If any one of the three amplifier channels should fail, it is likely that a large DC voltage will occur at the output of that channel. If this occurs, the DC offset detect circuit will cause the AM-3P II amplifier power supply to shut down. It will remain shut-down until the unit is unplugged from the power source. This provides a safe indication to the customer that the unit requires service.

Detailed operation is as follows: The amplifier outputs are summed by resistors R149, R249, R318, and R418, and (low pass) filtered by capacitor C29. For a sustained DC offset, C29 will charge either negative or positive. A positive offset will trigger Q7 and a negative offset will trigger Q8. This in turn causes Q6 to conduct and latches Q5 permanently on. Q5 then shorts the emitter of Q4 to ground (off). Q4 is the transistor that controls turn-on of 2P1T relay K1 (on the Amplifier PCB) that is used to connect +/- 20V supply rails to the power amplifiers. Thus, the amplifiers are de-energized.

AM-3P II DISASSEMBLY/ASSEMBLY PROCEDURES

Bass Module

NOTE: Refer to Figures 6 and 7 (pages 29 and 30)

for an exploded view of the module. Numbers in parentheses reference the individual parts displayed in these Figures.

1. Cover Removal

A. Remove the cover cap (1) by using the flat

edge of a screwdriver or your fingers. Find the recess on one side of the cap and lift the cap up and away from the cover (3).

B. Remove the screw (2) located under the cover cap.

C. Pull the 3 (friction fit) control knobs (4) directly out from the module.

D. Stick your fingers into the control knob holes. Swivel the cover carefully away from the Main PCB connector panel (5) and pull it away from the module.

2. Cover Replacement

3. Main PCB Assembly Removal

A. Remove 3 screws (6) that secure the Main

PCB (5) to the adapter bracket (8).

IMPORTANT: The connector gasket (7) has a light adhesive backing. Be careful not to tear it during removal.

B. Pull the connector gasket carefully away from the PCB connector panel.

C. Release the PCB from the 4 adapter bracket snaps (not shown), one edge at a time.

D. Unplug the flat, 16-pin cable (13) connecting the Main PCB to the Amplifier PCB (11).

E. Disconnect the 5-pin connector housing, J5, (which is connected to the transformer assembly’s (18) primary side), by pulling the PCB carefully up from the unit. Unhook the connector housing from the slot on the adapter bracket (see balloon view in Figure 6).

A. Hook the cover (3) into place by slanting the cover slightly forward (with connector panel facing you) and aligning the appropriate holes with the PCB connector panel.

B. Snap the cover into place.

C. Replace the 3 control knobs (4) by pushing

them in towards the module. The knobs are keyed and will only fit one way.

D. Secure the cover to the module with 1 screw (2).

E. Hook the cover cap (1) into place. The notched edge must align with the module’s label side.

IMPORTANT: The J5 connector pins fit snugly into the mating connector housing. Take care when attempting to unhook this connector.

4. Main PCB Assembly Replacement

A. Hook the J5 connector housing into the slot on

the adapter bracket (8). See the balloon view in Figure 6.

NOTE: Connector J5 has a unique keying feature and can only be connected one way.

B. Lower the PCB (5), solder side up, into position. The PCB’s connector panel must align with the module’s label side. Make sure that the pins on connector J5 line up with it's mating connector housing (transformer primary wires).

C. Push down the corners of the PCB until all 4

adapter bracket snaps (not shown) engage. Make sure that the J5 connector pins are completely inserted into the mating connector housing.

D. Plug in the flat, 16-pin cable (13) to the PCB.

7. Amplifier PCB Assembly Removal

NOTE: It is not necessary to completely

disassemble the unit to access the Amplifier PCB (11). Follow the simplified steps A-D below if direct access to this PCB is required and you have not already disassembled the unit.

E. Secure the PCB to the adapter bracket with 3 screws (6).

F. Place the connector gasket (7) over the connector panel.

5. Adapter Bracket and Heatsink Removal

NOTE: It is only necessary to remove 3 screws

(10) to remove the adapter bracket (8). These screws are located on the same side as the module’s labels. The bracket hooks onto a flange that is part of the heatsink (9). If further disassembly of the unit is required, then all 6 screws (10) should be removed.

A. Remove 6 screws (10) that secure the adapter bracket and the heatsink to the module.

B. Pull the bracket and heatsink away from the module.

A. Remove the cover (3) using Procedure 1.

B. Unplug the flat 16-pin cable (13) connecting

the Main PCB to the Amplifier PCB.

C. Remove 6 screws (10) that secure the adapter bracket (8) and heatsink (9) to the module.

D. Lift the Main PCB (5), adapter bracket and heatsink away from the module.

NOTE: The Main PCB should remain connected to the transformer primary side. It should also remain secured to the adapter bracket with 3 screws (6).

E. Lift up the Amplifier PCB (11) and unhook connectors J1 and J4 from the PCB. J4 is

connected to the woofer and J1 is connected to the transformer assembly’s (18) secondary side. Pull the PCB away from the unit.

NOTE: The Amplifier PCB Assembly (11) may be

stuck to the heatsink with thermal grease.

6. Adapter Bracket and Heatsink Replacement

A. Lower the heatsink (9) into position on top of

the Amplifier PCB (11). Make sure that the side of the heatsink with smaller fins is aligned with the module’s label side.

B. Align the screw holes on the heatsink with those on the transformer cup (19).

C. Hook the adapter bracket (8) onto the heatsink flange. Lower the adapter bracket into position. The bracket has screw holes only on one side. These should be aligned with the screw holes on the module’s label side.

D. Secure the heatsink and adapter bracket to the module with 6 screws (10).

F. Remove the two transistor spring clips (14) that rest on the transformer cup (19).

8. Amplifier PCB Assembly Replacement

A. Place the two transistor spring clips (14) on

the transformer cup (19).

B. Connect the J4 connector to the safetycontrolled woofer cable (24) and connector J1 (5 pin) to the transformer assembly’s (18) secondary side. When facing the module's label side, the transformer's secondary side is on the right.

NOTE: The large capacitors on the Amplifier PCB (11) fit into one side of the transformer cup (19).

C. Lower the PCB (solder side up) into place on

top of the transformer cup. There are holes in each corner of the PCB that align with the locator pins on the cup. The transistors (on PCB edges) should rest lightly on the transistor spring clips (14). Place the transformer primary connector wires into the slot on the PCB.

B. Align the screw holes on the transformer with those on the cup.

C. Secure the transformer to the cup with 4 screws (15) and 4 washers (16) using a 3/32-inch Allen wrench.

NOTE: If no further servicing is required, use the simplified steps below to reassemble the unit.

D. Replace the heatsink (9) using Procedure 6, steps A and B.

E. Place the transformer primary into the slot on

the Amplifier PCB (11).

F. Secure the adapter bracket (8) and Main PCB (5) using Procedure 6, step C.

G. Secure the heatsink, adapter bracket and Main PCB to the module with 6 screws (10).

H. Replace the cover (3) using Procedure 2.

9. Transformer Assembly Removal

NOTE: If direct access to the transformer is

required and the unit has not been disassembled, refer to the simplified steps provided in Procedure 7, along with step A of this procedure.

A. Remove 4 screws (15) and 4 washers (16) using a 3/32-inch Allen wrench and lift the transformer assembly (18) out of the transformer cup.

NOTE: If no further servicing of the unit is required, refer to the simplified steps provided in

Procedure 8 to reassemble the unit.

11. Transformer Cup and Gasket Removal

NOTE: To directly access the transformer cup

and gasket, follow the simplified steps provided in Procedure 9, then proceed with steps A and

B of this procedure.

A. Remove 2 screws (10) that secure the

transformer cup (19) to the module and lift the transformer cup away from the module.

NOTE: There might be woofer connector wires (safety controlled cable (24)) taped over the transformer cup gasket (20). Note the location of the cable relative to the module. Remove the tape and move the wires aside.

B. Remove the transformer cup gasket.

12. Transformer Cup and Gasket Replacement

NOTE: The transformer cup gasket (20) has

raised edges that should be face up when positioned in the transformer cup. The gasket also has a U-shaped opening that aligns precisely with the module.

NOTE: With the module’s label side facing you, the transformer’s primary side is on the left and the secondary side is on the right.

10. Transformer Assembly Replacement

NOTE: The transformer bracket (part of the

assembly) has a bent flange in one corner that will only allow the transformer to fit in the transformer cup (19) one way.

A. Lower the transformer assembly (18) into the transformer cup.

A. Place the gasket in position over the opening of the module.

B. Lay the woofer cable (24) over the appropriate corner of the bass module. The wires must cross over the top of the gasket.

C. Position the transformer cup. The cup has a locating ridge and only fits into the module one way. The lip should be aligned with the U-shaped opening in the module.

D. Secure the cup to the module with 2 screws

(10).

NOTE: If no further servicing of the unit is required, refer to the simplified steps provided in

Procedure 10 to reassemble the unit.

13. Woofer Removal

C. Remount the woofer (21) to the module using

4 screws (22). Repeat the woofer test procedures.

NOTE: If no further servicing of the unit is required, use the following simplified procedures to reassemble the unit.

NOTE: If direct access to the woofer is required and the unit has not already been disassembled, use the following simplified steps A-D.

A. Remove the cover (3) using Procedure 1.

B. Remove the Main PCB (5), heatsink (9) and adapter bracket (8) using Procedure 7, steps C and D.

C. Lift up the Amplifier PCB (11) and unhook the

safety controlled woofer cable (24) from the J4 connector (Amplifier PCB).

D. Remove the transformer cup (19) and gasket (20) using Procedure 11.

E. Remove 4 screws (22) that secure the woofer (21) to the baffle (part of the module). See

Figure 7.

14. Woofer Replacement

NOTE: Refer to Figure 7 for an exploded view.

D. Replace the transformer cup (19) and gasket (20) using Procedure 12.

E. Replace the transformer assembly (18) using Procedure 10.

F. Reinstall the Amplifier PCB (11) using Procedure 8.

G. Reinstall the heatsink (9) and adapter bracket (8) using Procedure 6.

H. Reinstall the Main PCB (5) using Procedure

I. Replace the cover (3) using Procedure 2.

Satellite Procedures

NOTE: Refer to Figure 8, page 30 for an

exploded view of the satellite. Numbers in parentheses reference the individual parts displayed in this figure.

A. Carefully lift the woofer out and cut the wires connected to the woofer terminals as close to the terminals as possible.

NOTE: Make a note of the woofer terminal orientation relative to the module. The woofer should be repositioned in it's original location.

B. Strip the wires and connect to a replacement woofer. Make sure that the red wire is connected to the positive (+) terminal and the black wire is connected to the negative (-) terminal. When repositioning the woofer, make sure that the woofer gasket (23) is correctly positioned behind the woofer to make an airtight seal.

1. Grille Removal

Hold the satellite enclosure (5) with one hand. Use your other hand to squeeze and pull the grille assembly (1) away from the satellite enclosure.

2. Grille Replacement

Align the grille assembly so that the curved edges are at the top and bottom of the enclosure. The nameplate (7) should be at the bottom right corner of the enclosure. Snap the grille gently into place.

3. Twiddler Removal

7. Connector Removal

A. Remove Grille from enclosure. Use

Procedure 1.

B. Remove the 4 screws (3) holding the twiddler

(2) in place. Lift the twiddler out and cut the wires connected to the twiddler as close to it's terminals as possible.

4. Twiddler Replacement

A. Strip the wires and connect them to the

replacement twiddler (2).

NOTE: The positive (+) terminal of each twiddler is marked with a red dot.

B. Connect the red wire to the positive (+) twiddler terminal and the black wire to the negative (-) twiddler terminal.

C. Lower the twiddler into the satellite enclosure and secure the twiddler to the enclosure with 4 screws (3). Repeat the satellite test procedures.

Use Procedure 1 and 3 to access the inside of the satellite enclosure.

A. After the twiddler has been removed, pull out the polyester batting (4) from the enclosure.

B. Use a pair of pliers to press the connector's (6) release snaps together. Push the connector out of the enclosure.

C. Cut the wires to the connector as close as possible.

8. Connector Replacement

A. Strip the wires and connect them to the

replacement connector (6).

NOTE: The positive (+) terminal is marked red. B. Connect the red wire to the positive (+)

terminal and the black wire to the negative (-) terminal.

D. Return the Grille Assembly to the front of the Satellite Enclosure.

C. Press the terminal into the back of the enclosure until it snaps into place.

AM-3P II TEST PROCEDURES

Satellite Test Procedures

NOTE: These procedures test the satellite

without the bass module.

1. Sweep Test

A. Connect an oscillator to a power amplifier.

Adjust the amplifier output to 4 Vrms. Connect the amplifier leads to the satellite (cube speaker) input terminals. Sweep the oscillator from 100 Hz to 5 kHz. If any twiddler buzzes or sounds distorted, replace it.

2. Phase Test

IMPORTANT: Supply voltage should only be

momentarily applied to the satellite input terminals to avoid possible damage to the twiddlers.

A. Set a DC power supply to 8 volts. To ensure that each twiddler is connected in phase, connect the positive supply lead to the positive (+) satellite input terminal (red) and the negative supply lead to the negative (-) satellite input terminal (black). The twiddler should move outwards with the application of the supply voltage.

NOTE: If any twiddler cone deflects inwards or does not move, check all connections.

Woofer (Module) Test Procedures

NOTES: These procedures test the bass module

without the satellites. All tests should be performed with the bass and treble control knobs in the normal or "detent" position and the volume control knob at maximum volume.

It may be necessary to disassemble the module in some of these procedures. Refer to the Disassembly/Assembly Procedures section for specific instructions.

1. Turn-On Test

NOTES: Refer to the AM-3P II Main PCB schematic for the location of the J7 mini-jack

input, pins 1 and 3. The On/Off Control Circuit is located on this schematic.

This test can be performed with a fully assembled module.

This procedure also refers to the “ring” and “sleeve” of a standard 3.5 mm mini-jack.

A. Connect an oscillator to the module’s L/R audio input terminals. Adjust the oscillator to 500

Hz, 220 mVrms.

B. Insert a 3.5 mm mini-jack into the input

terminal labeled “System Control”. The audio signal should mute.

C. Set a DC power supply to 8 volts and apply this voltage between pins 3 (ring) and 1 (sleeve, which is connected to ground) of the mini-jack. The audio signal should return.

2. Sweep Test

NOTE: This test can be performed with a fully

assembled module.

A. Connect an oscillator to the module’s L/R audio input terminals. Adjust the oscillator to 100

Hz, 220 mVrms. Sweep the oscillator from 10300 Hz. There should not be any loud,

extraneous sounds. If there are any loud buzzes or distortion, replace the woofer.

NOTE: There should not be any buzzes or rattles from within the module. Redress any wire or component that buzzes or rattles.

3. Tone Control Test

Frequency Relative Response

NOTE: This test can be performed with a fully

assembled module.

A. Connect an oscillator to the module’s L/R audio input terminals. Adjust the oscillator to 100

Hz, 220 mVrms.

B. Rotate the bass control knob fully clockwise

and counterclockwise from it's center or “normal” position. The bass level should increase and decrease cleanly without making a scratchy noise. Clean or replace any potentiometer that makes this noise.

C. Repeat this procedure for the treble control using a frequency of 4 kHz.

4. Frequency Response of L/R (Twiddler) Channels

NOTE: This test can be performed with a fully

assembled module.

A. Connect an oscillator to the module’s L/R audio input terminals. Adjust the oscillator to 1 kHz, 200 mVrms. Connect a piece of test equipment capable of measuring decibels to either the left or right twiddler output terminals (labeled “To Cube Speakers”). Measure the dBs at this setting and use this as a 0 dB reference.

B. Once the left or right output terminals of the cube speaker are connected, adjust the oscillator frequency and measure the relative response according to the chart located at the end of this procedure.

360 Hz -2.1 dB ± 1.5 dB

1 kHz 0 dB

2 kHz -3.5 dB ± 1.5 dB

10 kHz -.4 dB ± 1.5 dB

20 kHz -2.9 dB ± 2.0 dB

5. Twiddler Power Output Test

NOTE: This test can be performed with a fully

assembled module.

A. Connect a 4Ω resistive load across the left or right twiddler output terminal (labeled “To Cube Speakers”). Connect a voltmeter across the load.

NOTE: These measurements can be obtained at 120 and 240 V. Results will vary depending on the line voltage used.

B. Connect an oscillator to the module’s L/R audio input terminals. Adjust the oscillator to 1

kHz, 454 mVrms.

C. Measure the voltage across the load. It should

be approximately 8.9 volts (20 watts). The signal should look undistorted when viewed on an oscilloscope.

6. Twiddler Short Circuit Protection Test

C. Repeat this test for the other channel.

Frequency Relative Response

100 Hz -15.6 dB ± 2.0 dB

200 Hz +5.7 dB ± 1.5 dB

NOTES: This test can be performed with a fully assembled module.

IMPORTANT: Do not short out for longer than 1 second.

A. Adjust the oscillator to 1 kHz, 200 mVrms. Short the left or right twiddler output terminal. The signal should mute for approximately 3 seconds.

7. Air Leak Test

9. Woofer Phase Test

NOTE: Part A of this test can be performed with

a fully assembled module.

A. Connect an oscillator to the module’s left/right (L/R) audio input terminals. Adjust the oscillator to 40 Hz, 1 Vrms. Listen for air leaks around the transformer cup gasket. If there is a “whooshing” noise, there is probably an air leak around the gasket. Refer to the Disassembly/Assembly Procedures section for instructions on accessing this gasket. Reposition the transformer cup gasket under the cup to make an airtight seal.

NOTE: In order to perform the remaining procedures, it is necessary to disassemble the module to the woofer level. Leave all connections intact to perform these tests. Remove the cover using the procedures in the Disassembly/ Assembly Procedures section. Remove 6 screws that secure the heatsink to the module. Remove 2 screws that secure the transformer cup to the module. Slide out the transformer cup and PCBs carefully. Lay the module on it's side to access the woofer more easily.

B. Using the same oscillator setting as part A, listen for air leaks around the woofer gasket. If there is a "whooshing" noise around the gasket, reposition the woofer gasket behind the woofer to make an airtight seal.

A. Disconnect the woofer (connector J4) from the Amplifier PCB. Set a DC power supply to 8 volts. Connect the positive supply lead to the

positive (+) woofer connection (red) and the negative supply lead to the negative (-) woofer connection (black). The woofer should move outwards with the application of the supply voltage.

10. Frequency Response of Bass Channel

NOTES: Pull the heatsink away from the Amplifier PCB to expose the board's solder

side. It will be necessary to access the woofer output connector (J4) to perform the remaining procedures.

Bass amplifier output measurements are made across J4 pins 1 and 2. The amplifier uses a bridged output. Do not connect either output to ground. Any test equipment that will be connected to these points must be floated, or isolated from ground.

A. Make up a temporary set of connections to the woofer output connector J4.

B. Connect an oscillator to the module’s L/R audio input terminals. Adjust the oscillator to 100

Hz, 200 mVrms.

8. Woofer Rub and Tick Test

A. Connect an oscillator to the module’s L/R audio input terminals. Adjust the oscillator to 10 Hz, 1.5 Vrms. No extraneous noises such as

rubbing, scraping or ticking should be heard.

NOTE: To distinguish between normal suspension noise, rubs or ticks, displace the cone on the woofer slightly with your fingers. If the noise can be made to go away or get worse, it is a rub or a tick and the woofer should be replaced. If the noise stays the same, it is normal suspension noise and the woofer is fine. Suspension noises will not be heard with program material.

C. Connect a piece of test equipment capable of measuring decibels to the woofer output connector J4. Make sure that the meter is not grounded. Measure the decibels at this setting and use as a reference for all other readings.

D. Adjust the oscillator frequency and measure the relative response according to the chart located at the end of this procedure (next page).

Frequency Relative Response

20 Hz -18.0 dB ± 2.0 dB

C. Measure the voltage across the load. It should be approximately 15.8 volts (50 watts). The signal should look undistorted when viewed on an oscilloscope.

55 Hz +1.8 dB ± 1.5 dB

100 Hz 0 dB

200 Hz -0.5 dB ± 1.5 dB

400 Hz -10.7 dB ± 1.5 dB

11. Bass Channel Dynamic EQ Gain

NOTE: Use the same test setup as Procedure 10.

A. Adjust the oscillator to 100 Hz, 30 mVrms. Use

this as a reference point.

B. Adjust the oscillator to 55 Hz. There should be a boost of approximately 5 dB. (A 3.0 dB ± 1.0 dB difference between the 30 mV and the 200 mV input level). Refer to the chart in the previous procedure.

Complete System Tests

NOTE: Use these procedures when a complete

AM-3P II system (module and satellites) is to be serviced.

1. System Phase Test

Use the procedures already listed for the satellites and the module. Use Procedure 2 under Satellite

Test Procedures and Procedure 9 under Module Test Procedures.

2. System Sweep Test

Use the procedures already given for the satellites and the module,except use 220 mVrms for both parts of the test. Use Procedure 1 under Satellite

Test Procedures and Procedure 2 under Module Test Procedures. Make sure that the satellites are

connected to the bass module.

3. All Other Tests

12. Woofer Power Output Test

NOTE: Use the same test setup as Procedure 10, except remove the dB meter. Make sure that any

test equipment connected to the woofer output is floated or isolated from ground.

A. Connect a 5Ω resistive load to the woofer output. Connect a voltmeter across the load.

NOTE: These measurements can be obtained at 120 and 240 V. Results will vary depending on the

line voltage used.

B. Connect an oscillator to the module’s L/R audio input terminals. Adjust the oscillator to 100 Hz, 345 mVrms.

All other tests listed under Module Test Procedures can be used to test a complete system.

Figure 5. 120/240V Transformer Schematic

Secondary Load Line (@ Nominal Primary Voltage):

Vout = 21.0 Vdc Maximum (Referenced to C.T.) @ No Load

Vout = 14.0 Vdc ± 5% (Referenced to C.T.) @ Idc = 3.2 A

V1 = 10.0 Vrms ± 10% (Referenced to C.T.) @ No Load

Exiting Current @ 10% High Line: 200mA @ 132 Vrms, 60 Hz

300mA @ 264 Vrms, 50 Hz

Primary Voltage: 120 Vrms, 60 Hz Nominal (Test Circuit A)

240 Vrms, 50 Hz Nominal (Test Circuit B)

INTEGRATED CIRCUIT DIAGRAMS

NPN

Quad Transistor Array, NPN

P/N 145317 (MPQ3904)

Main PCB Assembly

1 Collector 2 Base 3 Emitter 4 No Connection 5 Emitter 6 Base 7 Collector 8 Collector

9 Base 10 Emitter 11 No Connection 12 Emitter 13 Base 14 Collector

A Output

A -Input

A +Input

Dual Operational Amplifier, DIP-8

P/N 108568 (RC 4559)

Main PCB Assembly

U2, U3, U5, U6, U101-105

B Output

B -Input

B+Input

IN-

IN+

Pin Pin

Comment

Name

1 NC No Connection 2 IN- Inverting Input 3 IN+ Non-inverting Input

Output

4 V- Negative Power Supply Input 5I

ABC

Amplifier Bias Input

6 Out Amplifier Output 7 V+ Positive Power Supply Input

= (V+)-(V-)

INB

8 NC No Connection

Bipolar Operational Transconductance Amplifier

P/N 119834 (CA3080)

Main PCB Assembly

Pin 146234

NJM78LO8A-T3

146235

NJM79LO8A-T3

1 Output Ground 2 Ground Input 3 Input Output

Amplifier PCB Assembly +8 Volt Regulator 146234, U1

-8 Volt Regualtor 146235, U2

Balance

Input

Pin Pin

Comment

Name

1 N1 Offset Voltage Null Input 1 2 -IN Inverting Input 3 +IN Non-inverting Input 4 V- Negative Power Supply Input 5 N2 Offset Voltage Null Input 2 6 Out Amplifier Output 7 V+ Positive Power Supply Input 8 NC No Connection

Output

Balance

Single JFET Input Operational Amplifier

P/N 250475-001 (LF355CN)

Amplifier PCB Assembly

U106, U206, U301, U401

PART LISTS AND EXPLODED VIEWS

The following section contains part lists and exploded views for the AM-3P II powered speaker system. The part lists and views are broken down as follows:

• Bass Module part list and exploded view. A view of the woofer is

contained in a separate figure.

• Satellite part list and exploded view.

• Packaging part list and exploded view.

• PCB Assembly part lists. PCB layouts and schematics are located in the back of the service manual.

IMPORTANT: Part changes were recorded by PC board revision level. Before

replacing or ordering parts check the revision number on the PC Board. Compare the PCB information with the part list, this will provide an accurate way of determining the value and part number of the replacement part. PC boards are

marked as follows:

AM-3P II Bass Module Part List (Figures 6 and 7)

Item

Number

1 Cap,Cover,White 145105-1 1

Cap,Cover,Black 145105-2 1 2 Screw,Machine,8-32x.5,Pan,XREC 121316-08 1 3 Cover,Black 144590-0222 1

Cover,White 144590-0231 1 4 Knob,Control,White 148839-1 3

Knob,Control,Black 148839-2 3 5 PCB Assy.,EQ,US/International 193567-1 1 1,2

PCB Assy.,EQ,Europe 175302-3 1 1,2

PCB Assy.,Multimedia,

US/International

PCB Assy.,Multimedia,Europe 175302-5 1 1,2 6 Screw,Hilo,6x.5,Pan,XREC 127015-08 3 7 Gasket,Cover-Connector 146208 1 8 Bracket,Adapter,Black 144587-2 1

Description Part Number Qty

Per

Assy

175302-4 1 1,2

*See Note

9 Heatsink,7.41x5.34x2.11 144588 1

10 Screw,Tapp,8-11x1, pan, XREC/SQ 172672-16 8 11 PCB Assy.,Amplifier 149374 1 1,2 12 Tape Foam,3" 129284-030 1 13 Cable,Flat,16-pin,Terminated 144437 1 14 Clip,Spring,Transistor 144591 4 15 Screw,Shoulder,8-32x.312,Sock,Hex 143444-04 4 16 Washer,Flat,.195" 146981 4 17 Grommet,Isolator,.563" 143445 4 18 Transformer,Power,120/240V 143051 13 19 Cup,Transformer,Black 144589-2 1 20 Gasket,Transformer Cup 143514 1

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 located on the PCBs are listed in the Electrical Part Lists.

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.

AM-3P II Bass Module Part List (Figures 6 and 7)

Item

Number

21 Woofer Assy. 5.25" 143357 1 22 Screw,Tapp,8-11x.75,pan, XRC/SQ 172672-12 4 23 Gasket,Woofer,6.5" 104794-08 1 24 Cable,Speaker 143513 1

Item

Description Part Number Qty

AM-3P II Satellite Part List (Figure 8)

Description Part Number Qty See

Number

1 Grille Assy,Satellite,Black 175177-1 1

Grille Assy,Satellite,Black 175177-2 1

Grille Assy,Satellite,Gray 175177-3 1

Per

Assy

See

Note

2 Twiddler,2.25" 147525 1 3 Screw,Tapp,8-11x.625, Pan,XRC/S 172672-10 4 4 Batting,Polyester,

144225 2

76mmx76mmx50 5 Enclosure,Satellite,Black 175213-1 1

Enclosure,Satellite,White 175213-2 1

Enclosure,Satellite,Gray 175213-3 1 6 Connector,Barrier Gltn,2 Pos,Blk 141405 1 7 Nameplate,Logo,Black 148056-1 1

Nameplate,Logo,Arc. White 148949-2 1

Nameplate,Logo,Gray 148949-3 1

Main PCB

J5 Connector Housing

13 14

PCB Connector Panel

Amplifier PCB

10 15

NOTE: WIRES SHOULD NOT CROSS UNDER GASKET OR TRANSFORMER CUP AREA.

Figure 6. AM-3P II Bass Module Exploded View

Transformer  Primary Side

Module Label

Figure 7. Woofer Location in Module

Release Snaps

Figure 8. Satellite Exploded View

AM-3P II Packaging List

Item

Number

1 Polybag,14.38x9.87x2 mil 103351 1 2 Manual,Owner's, 174871 1

Manual,Owner's,Multimedia only 175978 1 3 Card,Warranty, Universal 149225 1 4 Envelope,Blank,White 128450 1 5 List,Warranty,Service Stations,

N. America 6 Brochure, All Products,N. America 141478 1 7 Envelope, Warranty Registration,

N. America/International 8 Adaptor,Plug Stereo,Multimedia 128404 1 9 Adaptor,120/230V Polarized,Dual

Voltage

10 Sheet, Instruction Adaptor,Dual

Voltage

11 Sheet,Caution,AM Multimedia 179396 1

Description Part Number Qty

122706 1

123001 1

147013 1

147751 1

Per

Assy

See

Note

12 Cable,Stereo,Phono,Multimedia 176107-1 1

Cable,Stereo Input,5-Pin Connector,

Audio Input

13 Line Cord,Detachable,96",Europe 148203 1*

14 Polybag,13.5x33.5x9.13x3 mil 106595 1 15 Packing,Insert,Corrugated 149253 1 16 Packing,Corner Post,Bass Insert 148364 2

Line Cord,120V,Polar

Detachable,US/International

LineCord,230V,Australia,

Detachable

LineCord,230V,UK,

Detachable

143630 1

146999 1 * 134726 1 * 134725 1 *

*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.

AM-3P II Packaging List

Item

Description Part Number Qty

Number

17 Packing,Cushion 174448 2 18 Wire,18/2 Zip Cord,White,20 ft. 140236 2

Wire,18/2 Zip Cord,Alp White,20 ft.,

136693 2 Multimedia Wire,18/2 Zip Cord,Black,20 ft. 130915 2

19 Carton,RSC,AM-3P II,US/International 175004-00 1

Carton,RSC,AM-3P II,Ireland 175004-01 1 Carton,RSC,Multimedia 175938-00 1 Carton,RSC,Multimedia 175938-01 1

20 Carton,Alb,Satellite,AM-4 172939 1 21 Bag,Poly,7x9x2 mil,Satellite 175780 1

Per

Assy

See

Note

1 3

5 7 9

6 8

Satellites See Items 20 and 21

Figure 9. AM-3P II Packaging Exploded View

AM-3P II Main PCB Assembly Part List

Resistors

Reference

Description Part Number Reference

Designator

R1,29,*36,39,41, 43-46,52,59,60,

10.0KΩ,5%,1/8W, 1206

124895-1035

107,132,207,229, 232 *R2 Jumper Chip,1206 124896 R3,5,33,34,38,57, 149,249 R4,17,28,108,130, 208,230 R6,48,56,62 1 MΩ,5%,1/8W,

100KΩ,5%,1/8W, 1206 330Ω,5%,1/8W, 1206

124895-1045 124895-3315 124895-1055

1206 R7,8,*36,42,47,55, 58,68,129 R9,37,49,66,67 2.00KΩ,5%,1/8W,

20.0KΩ,5%,1/8W,

1206

124895-2035 124895-2025

1206 R10 27.4KΩ,1%,1/8W,

124894-2742

1206 R11,15,32,117,217 6.81KΩ,1%,1/8W,

124894-6811

1206 *R112,*212 17.4KΩ,1%,1/8W,

124894-1742

1206 R12,*112,*212 8.25KΩ,1%,1/8W,

124894-8251

1206 R13,24,69 5.11KΩ,1%,1/8W,

124894-5111

1206 R14,*100,*200 10Ω,5%,1/8W,1206 124895-1005

R16,18,35,50,51, *101,*102,103,104,

1.00KΩ,5%,1/8W,

1206

124895-1025

115,*201,*202,203, 204,215 R19,21 51.1KΩ,1%,1/8W,

124894-5112

1206 R20 2.00KΩ,1%,1/8W,

124894-2001

1206 R22 10KΩ,2%,1/4W,

121243-1211032

52mm,CF R25 18.2KΩ,1%,1/8W,

124894-1822

1206 R26,27,113,213 24.3KΩ,1%,1/8W,

124894-2432

1206 R30,53 91Ω,5%,1/8W,1206 124895-9105 R31,61,125,225 14.3KΩ,1%,1/8W,

124894-1432

1206

*P/N Change Rev. 1

*See Notes 3 and 4

*P/N at Rev. 0

*See Notes 3 and 4

*See Notes 1 and 2

*P/N Added at Rev. 1 *See Notes 1 and 2 *See Notes 1 and 2

*See Page 38 for reference column notes.

AM-3P II Main PCB Assembly Part List

Resistors (Continued)

Reference

Description Part Number Reference

Designator

R40 75.0KΩ,1%,1/8W,

1206 R54 162Ω,1%,1/8W,

1206

*R101,*102,*134, *201,*202,*234

*R105,*106,*205, *206

4.99KΩ,1%,1/8W,

1206

3.90KΩ,5%,1/8W,

1206 R109,209 681Ω,1%,1/8W,

1206 R110,210 6.19KΩ,1%,1/8W,

1206 *R111,*211 25.5KΩ,1%,1/8W,

1206

*R111,127,128, *211,227,228

12.1KΩ,1%,1/8W,

1206 R114,214 34.8KΩ,1%,1/8W,

1206 R116,216 20.0KΩ,1%,1/8W,

1206

*R105,*106,118, *205,*206,218

17.8KΩ,1%,1/8W,

1206 R119,219 2.37KΩ,1%,1/8W,

1206 R120,123,220,223 1.00KΩ,1%,1/8W,

1206 R121,221 221Ω,1%,1/8W,

1206 R122,124,222,224 100KΩ,1%,1/8W,

1206 R126,226 953Ω,1%,1/8W,

1206 R131,231 1.0Ω,5%,1/4W,

52mm,CF R133,233 1.0KΩ,,1/4W,2%,

52mm,CF VR1 Potentiometer,

RTRY,10KΩ,20%,

.05W,Dual VR2 Potentiometer,

RTRY,10KΩ,20%,

.05W,Dual VR3 Potentiometer,

RTRY,10KΩ,20%,

.05W,Single

124894-7502 124894-1620 124894-4991 124895-3925 124894-6810 124894-6191 124894-2552 124894-1212 124894-3482 124894-2002 124894-1782 124894-2371 124894-1001 124894-2210 124894-1003 124894-9530

121243-1211R05

121243-1211022

145311

145312

145313

*See Notes 3 and 4

*See Notes 1 and 2

*See Notes 3 and 4

*See Notes 1 and 2

*See Notes 3 and 4

*See Page 38 for reference column notes.

AM-3P II Main PCB Assembly Part List

Capacitors

Reference

Description Part Number Reference

Designator

C1-4,28,30,32,35, 36,101,102,126,

10uF,20%,16V,105,

EL 201,202,226

C6,7,9,10,13,14, 112,212

C8,120,121,122, 123,124,220,221,

.47uF,5%,50V,85,

BOX

.033uF,20%,50V,

Z5U,1206 222,223,224

C11,103,105,111, 115,203,205,211,

100pF,10%,50V,

1206,SL 215

C12,29,34,104,204 47uF,20%,16V,105,

EL C15,113,114,213,

214

.12uF,5%,50V,85,

BOX C16,*106,*206 .0082uF,5%,50V,85,

FILM C17 33uF,20%,16V,BP,

85,EL *C106,*206 .0039uF,5%,50V,85,

Film C107,108,207,208 .082uF,5%,50V,85,

FILM C109,110,209,210 .0068uF,5%,50V,

85,FILM C118,218 .001uF,5%,50V,85,

FILM C119,219 470pF,10%,50V,SL,

DISC

*C125,*127,*225, *227

C31,116,117,216, 217

680pF,10%,50V,SL,

1206

3300pF,10%,50V,

Y5P,1206

.1uF,5%,50V,85,

FILM

137126-100

137127-474

124958-3331

124956-1012

137126-470 137127-124 137123-822 147522-330 137123-392 137123-823 137123-682 137123-102 137269-471

124956-6812

124957-332 137123-104

*See Notes 1 and 2

*See Notes 3 and 4

*See Note 1 and 2

Diodes

Reference

Designator

D2-10,12-15,17,18, *19, 101-104,108, 201-204,208

*D19 Zener,5.1V 136758-5231

Description Part Number Reference

Switching,75V,

300mA

121501

*See Page 38 for reference column notes.

*P/N at Rev. 0

*P/N Change Rev. 1

AM-3P II Main PCB Assembly Part List

Reference

Description Part Number Reference

Designator

Q1,5,7-9,11 BPLR,N,60V,

200mA,TO-92 Q2-4,6,10,12 BPLR,P,60V,

200mA,TO-92

Integrated Circuits

Transistors

117921 119168

Reference

Description Part Number Reference

Designator

U1 Transistor,Array,

Quad,N,DIP-14 U2,3,5,6,101-105 Op-Amp,Dual,

DIP-8,RC4559 U4 Op-Amp,Single,

DIP-8,CA3080

Connectors

Reference

Description Part Number Reference

Designator

J2 Connector,

Header,Rectangle,

15 POS *J5 Connector,Header,

5 POS *J5 Connector,Header,

5 POS *J7 Connector,Housing,

PCB MNT,2P,F,

GRN *J10 Connector,Housing,

PCB MNT,2P,F,

GRN J8 Connector,Housing,

Phono,Quad,4 POS J9 Connector,Barrier

GLTN,Quad,4 POS *J10 Connector,Housing

AC,2 POS,Female Connector,Fuse

Clip,1 POS,Female

145317 108568 119834

145305-15

145315-5 172323-5

145310

146563

145309 145308 145306 140347

*P/N at Rev. 0

*Part Change, Rev. 1

*See Notes 1 and 2

*See Notes 1 and 3

*See Notes 2 and 4

*See Page 38 for reference column notes.

AM-3P II Main EQ PCB Assembly Part List

Miscellaneous

Reference

Description Part Number Reference

Designator

*F1 Fuse,1.5A,250V,

143668-1500

20x5mm *S1A,*S1B Cable Assy.,

Quick Disc *S1A,*S1B Switch,Rocker,

145314 176259

SPST,Wired *S2 Switch,Slide,DPDT 145307

*See Note 5

*See Note 5 *P/N until 1/13/95

*See Note 5 *P/N as of 1/13/95

*See Note 5

*S1 Switch,Rocker,

SPST

143629

*See Note 5

Notes: 1. Used on PCB 175302-1 US/International

2. Used on PCB 175302-3 Europe

3. Used on PCB 175302-4 Multimedia US/International

4. Used on PCB 175302-5 Multimedia Europe

5. 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.

AM-3P II Amplifier PCB Assembly Part List

Resistors

Reference

Designator

R30,31 5.1Ω,5%,1/4W, R32,33,131,142,

231,242,303,313, 403,413 R34,138,238,308 1.00KΩ,5%,1/8W,

R130,141,230,241, 302,312,318,402, 412,418

*R132,*143,*232, *243,*304,*314, *404,*414

*R134,*145,*234, *245,*306,*316, *406,*416 R135,139,140,235, 239,240,301,307, 310,311,407,410, 411 R136,236 20.0KΩ,5%,1/8W,

R137,237,309 5.11KΩ,1%,1/8W, R144,244,317,417 10Ω,5%,1/8W,1206 124895-1005

R147,247 3.30KΩ,5%,1/8W, R146,246 0.1Ω,10%,2W,AX, R408 3.30KΩ,5%,1/10W, R409 20.0KΩ,5%,1/10W, W1,4,12,34,35,47 Jumper,Chip,0805 133627

W2,3,5-11,14-27, 29,30-33,36-42,45, 46,48,49

Description Part Number Reference

121243-1215R15

52mm,CF

10.0KΩ,5%,1/8W,

1206

100KΩ,5%,1/8W,

1206

51Ω,5%,1/4W,

Fusing

5.1 Ω,5%,1/4W,

Fusing

220Ω,5%,1/8W,

1206

Cut

0805

Jumper,Chip,1206 124896

124895-1035

124895-1025 124895-1045

130102-510

130102-5R1

124895-2215

124895-2035 124894-5111

124895-3325

146759 133626-3325 133626-2035

*See Note

AM-3P II Amplifier PCB Assembly Part List

Capacitors

Reference

Designator

C17,125,225 10uF,20%,16V,105, C18,120-123,126,

220-223, 226, 301-304,401-404

*C20,*24 560uF,20%,

*C21,*25 10KuF,20%,35V,

C22,23,26,27,124, 224,305,405

Reference

Designator

D105-107,205-207, 301,302,401,402

Description Part Number Reference

EL .0047uF,5%,50V,

X7R,1206

16V,105,EL 105,EL

.033uF,20%,50V, Z5U,1206

Diodes

Description Part Number Reference

300mA,75V, Switching

137126-100 131754-472

128548 *See Note

143623 *See Note 124958-3331

121501

Reference

Designator

Q1,102,103,110, 202,203,210,302, 303,310,402,403, 410

Q101,104,109,201, 204,209,301,304, 401,404

*Q105,*205,*305, *405

*Q106,*206,*306, *406

*Q107,*207,*307, *407

Transistors

Description Part Number Reference

BPLR,N,60V, 200mA,TO-92

BPLR,P,60V, 200mA,TO-92

BPLR,P,100V,1A, TO-92

BPLR,N,100V,1A, TO-92

BPLR,N,60V,15A, (Formed 145319-1)

117921

119168

140349 *See Note

140348 *See Note

129001 *See Note

*Q108,*208,*308, *408

*See Note on Page 41.

BPLR,P,60V,15A, (Formed 145319-2)

129002 *See Note

AM-3P II Amplifier PCB Assembly Part List

Integrated Circuits

Reference

Designator

U1 Voltage Regulator, U2 Voltage Regulator, U106,206,301,401 Op-Amp Single,

Reference

Designator

J1 Connector, Header J2 Connector,Header, J4 Connector,Header

Description Part Number Reference

8V,POS,TO-92 8V,NEG,TO-92 DIP-8,LF355CN

Connectors

Description Part Number Reference

Inline,PCB MNT,5P Rectangle,15 POS Inline, PCB MNT,2P

146234

146235

132604 or 250475-001

133220-05 145305-15 133220-02

Miscellanous

Reference

Designator

*K1 Relay,24 VDC,

LK6,11,23,34,35,40, 47,49,83

LK56 Cable,22AWG, *Z1 Bridge Rectifier

*Z2 Bridge Rectifier,

*NOTE: 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.

Description Part Number Reference

143622 *See Note

DPST, TV-3 RATE 0Ω,.2W,AX 139942

147077

5 Cond.,2.64"

147408 *See Note

50V,1.0A

148950 *See Note

60V,4.0A

SCHEMATICS AND PCB LAYOUTS

The layout and schematic foldouts included with this manual can be used for Revisions 0 through 2 PC boards.

The Main PCB had a slight etch change from revision 0 to 1, and a reversed insertion of diode D19, from revision 1 to 2. See the separate views for these etch and component differences. The foldouts are arranged as follows:

• Main PCB schematic backed by component side and solder side PCB layouts

• Amplifier PCB schematic backed by component side and solder side PCB layouts

SPECIFICATIONS AND FEATURES SUBJECT TO CHANGE WITHOUT NOTICE

1/95: REV. 0

Bose Corporation The Mountain Framingham, Massachusetts USA 01701

P/N 175032

FOR TECHNICAL ASSISTANCE OR PART ORDERS, CALL 800-367-4008

BOSE AM-3P II Schematic

Specifications and Main Features

Frequently Asked Questions

User Manual