BOSE AM-3P Schematic

Bose Acoustimass® 3 Powered Speaker

System Troubleshooting Guide

This Troubleshooting Guide refers to the amplifier and equalizer PCBs that are located in the
powered section of the Acoustimass Bass Module. Refer to the Bose Acoustimass 3 Powered
Speaker System Service Manuals, part numbers 149821 and 175032 for schematics,
PCB layouts and part lists.

Symptom Check

1. No audio, or distorted
audio output, power relay
K1 does NOT click on.

2. No audio, or distorted
audio output, power relay
K1 clicks on.

1. Fuse F1 and fuse holder.

2. Fractured solder joints at power on/off switch S1.

3. Serial Data jack J7 fractured solder or defective.

4. Ribbon cable unseated at J2 (check both ends).

5. Defective power transformer. Check primary
resistance.

1. Solder fractures at J2 on both EQ and Amp PCB.

2. Solder fractures at Amp PCB output transistors
Q107, 207, 307, 407, 108, 208, 308, 408.

3. Solder fractures at bridge rectifiers Z1 and Z2.

4. Check continuity of bridge rectifiers Z1 and Z2.

5. Check the values of the 5.1Ω fusing resistors
R134, 145, 234, 245, 306, 316, 406 and 416.

6. Check the values of the 51Ω fusing resistors
R132, 143, 232, 243, 304, 314, 404 and 414.

7. Check for DC offset at the output transistors.
If DC offset is found, check continuity of
transistors.

©

1998 Bose Corporation Part Number: 175032-TG1 Rev. 00

08/98