Bose Companion 3 Series II Service Manual page 33

SERVICE BULLETIN
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.
Component
R336
1N4148 Diode
Q303
J301
1
TP370
2
3
Date: 09/04
FINS: 1569
From
2.2 Ohm
+15V
R308
TP372 TP373
TP371
1.00K
PGND
Bose Corporation; The Mountain, Framingham, Ma. 01701-9168
Service documentation available online at http://serviceops.bose.com
Part Number
133625-2R25
+10V
R336
TP378
C
2.2ohm Q303
TP325 TP328
B
C
2SC4695
E
A
Add Diode
1
C311
R313-NV
10uF
2
1
D301
C
13v
C313
100uF
2 AGND
A
AGND
To Part Number
10 Ohm 133625-10R0
R336
+10V
TP334
R337 R316 R317 R319
402 249 249 249
TP376 TP377 TP375
MMBT3906
TP330 MMBT3906 MMBT3906
Q304
Q306 Q307
IABC2
IABC1
IABC3