JBL PowerBass PB12, Service Manual

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JBL Incorporated 250 Crossways Park Dr. Woodbury, New York 11797
Service Bulletin
Service Bulletin JBL2001-07 - November 2001 This is considered a Minor repair
To: All JBL Service Centers
Model: PB12
Subject: Possible Missing Diode D4
In the event you receive a PB12 subwoofer for any servicing reason, check for the presence
of diode D4 on the Main PCB close to the Power Amp Module (see illustration). If D4 is missing
or has been “cut out” of the circuit, it should be replaced; add JBL part# 50115. Observe
polarity.
Note: The presence or absence of D4, in itself, does not contribute to, or solve, an amplifer failure.
Purpose of D4 is to reduce the possibility of an occasional Turn-OFF pop noise.
Reference for general location only; all parts or designators may not conform exactly to this drawing.