JBL ESC 550 Source Service Manual / Technical Bulletin ▷ View online
Service Bulletin
Service bulletin JBL9706 - June 1997
Warranty labor rate: MINOR repair
To:
All JBL Service Centers
Models: ESC550 Subwoofer (Bass 550)
Subject: Unit stays in protect mode
In the event you receive a Bass 550 subwoofer (part of the ESC 550 system) with the complaint “unit
stays in protect mode” (demonstrated by a constantly lit red LED):
stays in protect mode” (demonstrated by a constantly lit red LED):
Procedure:
1) Remove the amplifier assembly from the subwoofer enclosure.
2) Locate power supply board PC1163; then locate C18 (10uf, 16v). See drawing.
3) Replace C18 with 10uf, 50v electrolytic radial cap (H/K# 3479210071). IMPORTANT NOTE:
2) Locate power supply board PC1163; then locate C18 (10uf, 16v). See drawing.
3) Replace C18 with 10uf, 50v electrolytic radial cap (H/K# 3479210071). IMPORTANT NOTE:
POLARITY SILKSCREEN ON PCB 1163 VERSION 00 IS INCORRECT. Make sure to inset the minus
lead of C18 into the hole closest to large electrolytic cap C3. The polarity printed on the PCB of units
with serial numbers xxx or less was reversed.
lead of C18 into the hole closest to large electrolytic cap C3. The polarity printed on the PCB of units
with serial numbers xxx or less was reversed.
4) Test diodes D5 and D6 in circuit with “diode check” function on DMM. Replace if defective. D5 is
H/K#2258100135; D6 is H/K#2058322101.
5) Re-assemble subwoofer and test.
.
.
Model
Serial number
Action
Correction
Bass550
Below 04618
Unit stays in Protect mode
Replace C18,
Check D5 & D6.
Bass550
04618 and above
Modified by factory
NONE REQUIRED
JBL Incorporated 80 Crossways Park West, Woodbury, New York 11797 (516) 496-3400
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