JBL PowerBass PB12, Service Manual

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JBL Incorporated 250 Crossways Park Dr. Woodbury, New York 11797
Service Bulletin
Service Bulletin JBL2001-05 - June 2001 This is considered a Minor repair
To: All JBL Service Centers
Models: PB12
Subject: Popping Every Few Seconds During Play
In the event you receive a PB12 subwoofer with the complaint: “The subwoofer “thumps” or “pops”
every few seconds of play”, follow the procedure below:
Probable Cause:
Inductor L1 (220uH) may be damaged.
Check and Replace L1 if necessary:
1) Set the unit on a padded surface and remove all external cables.
2) On the amplifier faceplate, remove the (10) Phillips mounting screws around the perimeter.
3) Remove the amplifier assembly from the enclosure. If the amp is supported correctly, no other
connectors need to be unplugged.
4) Locate Inductor L1 on the main PCB. If the windings appear charred or burnt, it must be replaced.
5) Order JBL part# 80121 and replace L1.
6) Replace the amplifier assembly back into the cabinet; replace the screws.
7) Test the unit and confirm the original problem has been corrected.