JBL PowerBass PB12 User manual

JBL Incorporated
250 Crossways Park Dr.
Woodbury, New York 797
REV210/2001
PowerBassTM Series
PB12Subwoofer
SERVICE MANUAL

PB12
TABLE OF CONTENTS
Safety Information ……………………………………………………….3
Basic Specifications ………………………………….………………….4
Detailed Specifications ………………………………………………….5
Controls and their Function …………….……………………………….6
Speaker Connection …………………….……………………………….7
Operation ………………………………….….………………………….10
Troubleshooting………………………………………………………….11
Test Setup and Procedure ……………………………….…………….12
Service Bulletin JBL 2001-03 ………………………………………….13
Service Bulletin JBL 2001-05 ………………………………………….14
Service Bulletin JBL 2001-07 ………………………………………….15
Exploded and Packaging ………………………………...…………….16
Amplifier Exploded View ……………………………………………….17
Amplifier Faceplate …………………………………..…………………18
Integrated Circuit Diagrams…………………………………………….19
Testing Procedure…………………………………….…………………20
Electrical Parts List (PCB version 6.3 – 7.0)………………………….23
Electrical Parts List (PCB version 7.2) …………………………..……28
Printed Circuit Boards (PCB version 6.3 – 7.0)…… ……...…..…….32
Printed Circuit Boards (PCB version 6.4)………..… ……...…..…….35
Printed Circuit Boards (PCB version 7.2)…… ……...……………….36
Schematics
Preamp (PCB version 6.3 – 7.0)…………………… ………….39
Power Amp (PCB version 6.0 – 6.3)…………..……………….40
Power Amp (PCB version 7.0)………………………………….41
Preamp (PCB version 7.2)…………………………….. ……….42
Power Amp (PCB version 7.2)………………………………….43

PB12
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SAFETY INFORMATION

PB12
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BASIC SPECIFICATIONS PB12 Subwoofer

PB12
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DETAILED SPECIFICATIONS PB12 Subwoofer

PB12
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PB12 Subwoofer Controls an their Function
1. Power - These lights will be red when the unit is
plugged in and not receiving a signal; when the PB 2
receives a signal, the lights will cycle to GREEN. If no
signal is received after 0- 5 minutes the lights will
cycle back to RED (standby) until a signal is present
again.
2. Level Control - The subwoofer Level Control, PB 2,
(located on the rear panel) adjusts the volume of the
subwoofer relative to the rest of the system.
3. LFE/Normal Switch - Ordinarily placed in the Normal
position - but switch to LFE when playing Dolby
DigitaL, DTS or other digital surround modes - see
page 9.
4. Phase Switch - Changes the subwoofer’s output to
be in phase or 80 degrees out of phase with the
program material.
5. Crossover Freq ency - Sets the highest frequency
the subwoofer will reproduce.
6. Line Inp t - Main Input connection to subwoofer
(preferred).
7. Speaker In Jacks - Main Input connection to
subwoofer when line level, subwoofer, or pre-amp
output connectors are not available, or when a high
pass filter (set at 50Hz) to main loudspeakers is
desired through the Speaker Output Jacks.
8. Speaker O t Jacks - Connected to main
loudspeakers when the Speaker Input Jacks are used.
9. Power Switch - Turns the PB 2 on or off.
Rear Panel
Front Panel

PB12
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Speaker Connection
When we designed the PB 0
and PB 2 powered
subwoofers, our goal was to
offer the user the best possible
performance combined with
the most flexible and complete
installation options. Please
look over the following three
examples to determine which
description best matches your
system and follow the
corresponding hookup
instructions.
To use the binding-post
speaker terminals with bare
wire, unscrew the collar until
the hole through the
centerpost is visible under the
collar.
Insert the bare end of the wire
through the hole in the post,
then screw the collar back
down until the connection is
tight. The holes in the center
of the collars are intended for
banana-type connectors.
Dolby Pro Logic (Non-Digital)-Speaker Level
Use this installation method for
Dolby Pro Logic applications
(not Dolby Digital, DTS or
other digital processing),
where the receiver/processor
does not have a subwoofer
output or a volume-controlled
preamp (line-) level output:
Connect your receiver or
amplifier’s front left and right
speaker terminals to the left
and right terminals on the
subwoofer that are marked
“High Level In.” Connect the
left and right terminals on the
subwoofer that are marked
“High Level Out” to the
corresponding terminals on the
back of your front left and right
speakers.
Connect your receiver or
amplifier’s center, left and right
surround-speaker terminals to
the corresponding terminals on
the back of your center, left
and right surround speakers.

PB12
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Dolby Pro Logic (Non-Digital)-Line Level
Use this installation method for
Dolby Pro Logic applications
(not Dolby Digital, DTS or
other digital processing),
where the receiver/processor is
equipped with a subwoofer
output or a volume-controlled
preamp (line-) level output:
Use RCA-type patch cords to
connect the line-level
subwoofer outputs on your
receiver or amplifier to the line-
level inputs on the subwoofer.
IMPORTANT: Make sure that
the LFE toggle switch on the
subwoofer is in the “Normal”
position. Do not use the “LFE”
position with Dolby Pro Logic-
only processors.
Note: If your receiver or
amplifier only has one
subwoofer output jack, then
you may connect the
subwoofer output on your
receiver/preamplifier to either
the left or right line-level input
on the subwoofer. It makes no
difference which jack you
choose.
Connect each speaker to the
corresponding speaker
terminals on your receiver or
amplifier.
Make sure your receiver or
processor is configured
correctly; Make sure that the
subwoofer is configured as
“On.”
Note for advanced users: If
your receiver/processor has a
built-in low-pass crossover
filter for the subwoofer output,
then the LFE switch should be
set to the “LFE” position to
bypass the subwoofer’s
internal crossover.

PB12
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Dolby Digital or DTS (or Other Digital Surroun Mo e) Connection
Use this installation method for
Dolby Digital, DTS or other
digital surround processors:
IMPORTANT: Make sure that
the LFE toggle switch on the
subwoofer is in the “LFE”
position. Use the line-level
input jacks for the low-
Frequency Effects channel.
Connect these jacks to the LFE
output or subwoofer output on
your receiver or amplifier.
Note: If your receiver or
amplifier only has one
subwoofer output jack, then
you may connect the
subwoofer output on your
receiver/preamplifier to either
the left or right line-level input
on the subwoofer. It makes no
difference which jack you
choose.
Connect each speaker to the
corresponding speaker
terminals on your receiver or
amplifier.
Make sure that you have
configured your surround-
sound processor for
“Subwoofer On”or “LFE On.”
The front left, front right, center
and rear speakers should be
set to “Small” or “Large”
depending on their size and
frequency response. Consult
your receiver’s or processor’s
owner’s manual.

PB12
0
OPERATION
Power
When the unit is plugged in
and the power switch is on
and no signal is received, the
LEDs on the front of the unit
will turn red. When a signal is
present, the LEDs will turn
green.
Note: It will take several
minutes for the LEDs to turn
from green to red after the
input signal to the subwoofer is
removed. Due to JBL’s
unique, high-output, high-
efficiency amplifier design,
power consumption is minimal
The subwoofer Level Control
adjusts the volume of the
subwoofer relative to the rest
of the system. Proper level
adjustments depends on
several variables such as
Level Control
room size, subwoofer
placement, type of main
speakers and listener position.
Adjust the subwoofer level so
that the volume of the bass
information is pleasing to you.
Crossover A justments
The Crossover Frequency
Control determines the highest
frequency at which the
subwoofer reproduces sounds.
If your main speakers can
comfortably reproduce some
low-frequency sounds, set this
control to a lower frequency
setting, between 50Hz- 00Hz.
This will concentrate the
subwoofer’s efforts on the
ultradeep bass sounds required
by today’s films and music. If
you are using smaller bookshelf
speakers that do not extend to
the lower bass frequencies, set
the low-pass crossover control
to a higher setting, between
20Hz- 50Hz. This control is
not used when the LFE switch
is in the “LFE” position.
when the subwoofer is not
receiving a signal.