BOSE 271885-B2 Schematic

SERVICE BULLETIN

Component

From

Part Number

To

Part Number

R336

2.2 Ohm

133625-2R25

10 Ohm

133625-10R0

Bulletin Part Number: 271885-B2

Product: Companion® 3 Multimedia Speaker System

Subject: No Audio Output

Disposition: All units in for repair with a no audio complaint.

Symptom: No audio output from the system and the control pod LED is dimly lit.

Reason: Q303 on the main PCB is defective or shorted completely.

Solution: Replace Q303 with part number 148770. Add a 1N4148 diode part number 121501 across the

base and emitter junction. Polarity is very important. Connect the cathode of the diode to the
base and the anode to the emitter. Refer to the figures below for the location of Q303 and
orientation of the diode. Also replace R336, as identified in the table below. Refer to the
Companion 3 Speaker System service manual part number 271885-SM.

1N4148 Diode

Date: 09/04
FINS: 1569

Q303

J301

1

2

3

TP370 TP371

PGND

+15V

TP372 TP373

R308

1.00K

R336

TP378

2.2ohm

TP325 TP328

Add Diode

D301

13v

C

B

C

A

E

C

A

Q303

2SC4695

1

2

C311
10uF

AGND

1

2

+10V

C313
100uF

R313-NV

AGND

Bose Corporation; The Mountain, Framingham, Ma. 01701-9168

Service documentation available online at http://serviceops.bose.com

TP330

+10V

R337
402

R316
249

MMBT3906

Q304

R336

TP334

R317
249

TP377

MMBT3906

Q306

IABC1

R319
249

TP375TP376

MMBT3906

Q307

IABC2

IABC3