JBL PB-12 Mk3 Service manual

JBL, Incorporated

250 Crossways Park Drive

Woodbury, New York 11797

REV 3 5/02

PowerBass

™

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 2001-04 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

Service Bulletin JBL 2001-05 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

Service Bulletin JBL 2001-07 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

Exploded and Packaging Views . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

Amplifier Exploded View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

Amplifier Faceplate/Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

Integrated Circuit Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

Testing Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

Block Diagram Revision 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

Electrical Parts List (PCB version 6.3 – 7.0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30

Electrical Parts List (PCB version 7.2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

Electrical Parts List Revision 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38

Printed Circuit Boards (PCB version 6.3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41

Printed Circuit Boards (PCB version 6.4) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44

Printed Circuit Boards (PCB version 7.2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45

Preamp Schematics (PCB version 6.3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48

Power Amp Schematics (PCB version 6.0 – 6.3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49

Power Amp Schematics (PCB version 7.0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50

Preamp Schematics (PCB version 7.2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51

Power Amp Schematics (PCB version 7.2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52

Preamp Schematics (Revision 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53

Power Amp Schematics (Revision 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54

PB12 – DIFFERENCES IN REVISION 1 AND REVISION 2

REVISION 1 REVISION 2

Amplifier faceplate says “Made in Canada” Amplifier serial number starts with “AM” Amplifier serial number starts with “HA” Black (or silver) potted, non-serviceable output module Output transistors in the open, on a large black heatsink

Large plastic cup enclosing the rear of the amp assembly Main PCB, bottom, solder-side contains all SMD devices “Made in Mexico” label on outer part of cabinet

BOTH VERSIONS OF THESE AMPLIFIERS ARE NOT CONSIDERED INTERCHANGEABLE; THEY ARE NOT A DROP-IN REPLACEMENT IN THE CABINET OF THE OTHER VERSION.

PB12

Warning

Any person performing service of this unit will be exposed to hazardous voltages and the risk of electric shock. It is assumed that any person who removes the amplifier from this cabinet has been properly trained in protecting against avoidable injury and shock. Therefore, any service procedures are to be performed by qualified service personal ONLY!

Caution

Before the amplifier is plugged in, be sure its rated voltage corresponds to the voltage of the AC power source to be used. Incorrect voltage could cause damage to the amplifier when the AC power cord is plugged in. Do not exceed rated voltage by more than 10%: operation below 90% of rated voltage will cause poor performance or may shut the unit off.

Leakage/Resistance Check

Before returning the unit to the customer, perform a leakage or resistance test as follows:

Leakage Current. Connect the unit to its rated power source. Using an ammeter, measure the current between the neutral side of the AC supply and chassis ground of the unit under test. If leakage current exceeds 0.5mA, the unit is defective. Reverse the polarity of the AC supply and repeat.

Resistance. Measure the resistance from either side of the line cord to chassis ground, If it is less than 500k ohms, the unit is defective.

WARNING! DO NOT return the unit to the customer if it fails one of these tests until the problem is located and corrected.

Critical Components

All components identified with the IEC symbol in the parts list and schematic diagram designate components in which safety can be of special significance when

replacing a component identified with. Use only the replacement parts designated in the parts list or parts with the same rating of resistance, wattage or voltage.

SAFETY INFORMATION

List of Safety Components Requiring Exact Replacements

Revision 1 Revision 2 Description

F1 - 80117 093-105202-300 Line Fuse Slo Blo 2.0A PWRCORD 083-041802-009 250V UL approved

80105 SPT-2 or better with

polarized plug, UL approved wired with the hot side to fused side. Use with factory replacement panel strain relief (70305) only.

TRX 042-010053-003 Power Transformer. Use 80116 only factory replacement.

BR RECT BR1 Bridge diode. Use only 50100 052-400080-000 factory replacement.

C1,2 C6,8 Large electrolytic filter (2200uF 100V) (3300uf 80v) caps. Be sure 30710 034-470745-200 replacement part is at

least the same working voltage and capacitance rating. Also the lead spacing is important. Incorrect spacing may cause premature failure due to internal cabinet pressure and vibration.

C10 Does not apply 4.7uF, 100 volt NPE low 30718 df radial.

(On Power amp PCB)

S64AMI Does not apply Power output module. 60302 Use only factory

replacement

Faceplate n/a Use only factory 70325 replacement

Rear Amp Cover 063-531808-000 Use only factory Does not apply replacement

Inductor Does not apply CMC - Use only factory 80100 replacement

Inductor Does not apply L1 - Use only factory 80121 replacement

Does not apply Inductor L2 - Use only factory

043-300101-000 replacement

Does not apply Inductor L3 - Use only factory

043-700101-000 replacement

PB12

BASIC SPECIFICATIONS PB12 Subwoofer

Output Power

Driver

Frequency Response

Inputs

Outputs

Low-Pass Frequency

High-Pass Frequency

Dimensions (H x W x D)

Weight

250 watts RMS

12" Woofer

25Hz – Low-Pass Frequency setting

Line Level (option: LFE); Speaker Level

Speaker level fixed frequency 150Hz

Variable from 50Hz – 150Hz

150Hz when using Speaker Level Output

15 1/2" x 15" x 16" 394mm x 381mm x 406mm (with feet) 17 1/2" x 15" x 16" 445mm x 381mm x 406mm

40 lb/18.2kg

00261-1

Refinements may be made on occasion to existing products without notice but will always meet or exceed original specifications unless otherwise stated. PowerBass is a re

istered trademark of JBL, Incorporated.

PB12

mits

@ Sp

signal applied

emoved

@ Sp

condition remova

times the input voltage

DETAILED SPECIFICATIONS PB12 Subwoofer

JBL PB12 250W Powered Sub Amp

LINE VOLTAGE Yes/No Hi/Lo Line Nom. Unit Notes

Parameter Specification Unit

Amp Section

Type (Class AB, D, other) D n/a

Load Impedance (speaker) 5.6 Ohms

Rated Output Power (120VAC) 250 Watts

Rated Output Power (230VAC) 250 Watts

THD @ Rated Power 0.3 %

THD @ 1 Watt 0.1 %

DC Offset 10 mV-DC

Damping factor >50 DF

Input Sensitivity

Input Frequency 50 Hz

L&R 240 mVrms

LFE input 240 mVrms

Speaker/Hi Level Input 2.4 Vrms

Signal to Noise

SNR-A-Weighted 90 dBA

SNR-unweighted 85 dBr

SNR rel. 1W-unweighted 65 dBr

Residual Noise Floor 1 mVrms

Residual Noise Floor 1.5 mVrms(max)

Input Impedance

Filters

LP filter 4th order fixed 60-180 Hz

Subsonic filter (HPF) 3rd Order Fixed

LFE Low pass 2nd order 200>LP<1K Hz

HP speaker out connector 200 Hz

Features --

Volume pot Taper (lin/log) LOG --

HP Speaker out YES

Phase switch 0-180 deg

LP Filter defeat switch YES

Input Configuration

Line In (L,R) & LFE

Spkr/Hi Level In YES --

Signal Sensing (ATO)

Auto-Turn-On (yes/no) YES

ATO Input test frequency 50 Hz

ATO Level LFE Input 4 mV

ATO Level Speaker in 50 mV

ATO Turn-on time 5 ms

Auto Mute/ Turn-OFF Time 15 minutes

Power on Delay time 3 sec.

Transients/Pops

ATO Transient 5 mV-peak

Turn-on Transient 50 mV-peak

Turn-off Transient 50 mV-peak

Efficiency 65 %

Stand-by Input Power 24 Watts

Power Cons. @ rated power 234 Watts

Protection

Short Circuit Protection YES

Thermal Protection YES

DC Offset Protection YES

Line Fuse Rating

USA-Domestic 2 Amps Type-T or Slo Blo-250 V

EU 1.25 Am

US 120vac/60Hz Yes 108-132 120 Vrms Normal Operation

EU 230vac/50-60Hz Yes 207-264 230 Vrms Normal operation, MOMS required

Conditions Notes

120 VAC-60 Hz

230 VAC-50 Hz

eaker Outputs

ower A-Weighting filter

ower 22k filter

ut 22k filter

ut driven onl

" Maximum acce

lied

eaker Outputs

e-T or Slo Blo-250 V External fuse with UL/SEMKO rated holder

At spkr cable. 150 Watts @ THD < 0.1 % @ 50 Hz

le input driven

le input driven, LFE switch ON

le input driven

Line level inputs must be terminated using 1KOHM

A Ta

Binding post connector L&R

table level.

Auto turn of time (T) must be 5 > T < 15 Minutes

Nominal Line volta

Maximum allowable input power under nominal

Input voltage and frequency, HOT or COLD

Amplifier should resume operation after short circuit

e 120 VAC

Line Input (L, R,LFE) 20K ohms

Speaker/Hi Level Input 4.7K ohms

100 Hz

YES -- functional Dual RCA jack

QA Test

n/a

Nominal

n/a

140 Domestic version onl

130 EU Version onl

22k filter 145 Watts

22k filter

0.5

Measured at amplifier board

Nominal Fre

To 150 Watts Sin

±2dB

To 150 Watts Sin

±2dB

To 150 Watts Sin

±2dB

relative to rated

relative to 1W Out

3 Volume @max, using RMS reading

DMM/VOM (or A/P) BW=20 Khz.

3 Volume @max, w/ A/P Swept

Bandpass Measurement (Line freq.+

Nominal

n/a

Nominal

n/a

± 10 2nd order variable + 2nd order fix-24 db/Octave

LFE in

± 10 S

functional

functional Refer to Filter section

functional

functional Disables LP filter, intended for LFE

functional

functional Amp connected and AC on, then input

15 T before muting, after signal is

n/a

2v-

240

functional

functional @1/8 max unclipped Power at 1.06

eaker input driven - 4 Ohms

eaker input driven - 8 Ohms

AC Power A

Speaker Outputs AC Line cycled from OFF to ON

Speaker Outputs AC Line cycled from ON to OFF

@ nom. line voltage

nom. line voltage 150 Watts @ 5.6 Ohms nominal line voltage

Direct short at output

DC present at Speaker Out leads

PB12

PB12 Subwoofer Controls and Their Function

1. Power - These lights will be red when the unit is

plugged in and not receiving a signal; when the PB12 receives a signal, the lights will cycle to GREEN. If no signal is received after 10-15 minutes the lights will cycle back to RED (standby) until a signal is present again.

2. Level Control - The subwoofer Level Control, PB12,

(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 180 degrees out of phase with the program material.

5. Crossover Frequency - Sets the highest frequency

the subwoofer will reproduce.

6. Line Input - 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 150Hz) to main loudspeakers is desired through the Speaker Output Jacks.

8. Speaker Out Jacks - Connected to main

loudspeakers when the Speaker Input Jacks are used.

9. Power Switch - Tu rns the PB12 on or off.

Rear Panel

Front Panel

PB12

Speaker Connection

When we designed the PB12 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 center-

post 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

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 linelevel 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 Logiconly 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 cor

rectly: Make sure that the

sub

woofer 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

Dolby Digital or DTS (or Other Digital Surround Mode) 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 LowFrequency Effects channel. Connect these jacks to the LFE output or subwoofer output on your receiver or amplifier.

Connect each speaker to the corresponding speaker terminals on your receiver or amplifier.

Make sure that you have configured your surroundsound 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

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 when the subwoofer is not receiving a signal.

The subwoofer Level Control adjusts the volume of the subwoofer relative to the rest of the system. Proper level adjustments depend on several variables such as 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.

Level Control

Crossover Adjustments

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 – 100Hz. 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 120Hz – 150Hz. This control is not used when the LFE switch is in the “LFE” position.

LEVEL

CROSSOVER FREQUENCY

PowerBass PB12

LINE LEVEL IN

+ –

ON OFF

POWER

PowerBass PB12

CAUTION

RISK OF ELECTRIC SHOCK

DO NOT OPEN

Min

LFE NORMAL

0º 180º

PHASE

50Hz

L R

For LFE use L or R

HIGH

LEVEL

HIGH

LEVEL

OUT

150Hz

120V 60Hz

Max

PB12

Phase Control

The Phase Control determines whether the subwoofer’s piston-like action moves in and out in phase with the main speakers or opposite the main speakers. There is no correct or incorrect setting. Proper phase adjustment depends on several variables such as subwoofer placement and listener position. Adjust the

phase switch to maximize bass output at the listening position.

Remember, every system, room and listener is different. There are no right or wrong settings; this switch offers the added flexibility to adjust your subwoofer for optimum performance for your specific listening conditions without having to move your speakers.

If at some time in the future you happen to rearrange your listening room and move your speakers, you should experiment with the phase switch in both positions, and leave it in the position that maximizes bass performance.

TROUBLESHOOTING

If you used the high-level (speaker) inputs and there is no sound from any of the speakers:

•

Check that receiver/amplifier is on and a source is playing.

• Check that powered

subwoofer is plugged into an active electrical outlet and is switched on.

• Check all wires and

connections between receiver/amplifier and speakers. Make sure all wires are connected. Make sure none of the speaker wires are frayed, cut or punctured.

• Review proper operation

of your receiver/amplifier.

If there is low (or no) bass output:

• Make sure the connections to the left and right “Speaker Inputs” have the correct polarity (+ and –).

• Make sure that the subwoofer is plugged into an active electrical outlet and switched on.

• Adjust the crossover point.

• Flip the Phase Control switch to the opposite position.

• If you are using a Dolby Digital/DTS receiver or processor, make sure that the subwoofer adjustments on the receiver/processor are set up correctly.

• Slowly turn the Level Control clockwise until you begin to hear the desired amount of bass.

If you used the line-level inputs and there is no sound from the subwoofer:

•

Check that receiver/amplifier is on and a source is playing.

• Check that powered subwoofer is plugged into an active electrical outlet and is switched on.

• Check all wires and connections between receiver/ amplifier and subwoofer. Make sure all wires are connected. Make sure none of the wires are frayed, cut or punctured.

• Review proper operation of your receiver/amplifier.

• Slowly turn the Level Control clockwise until you begin to hear the desired amount of bass.

• Make sure that you have configured your receiver/ processor so that the subwoofer/LFE output is on.

PB12

PB12 TEST SETUP AND PROCEDURE

General Function UUT = Unit Under Test

1. Connect one line level input cable (RCA) from signal generator to either Right or Left Level input on UUT. VOLUME control should be full conterclockwise. Make sure the LFE/Normal switch is in the NORMAL position.

2. Turn on generator, adjust to 100mV, 50Hz.

3. Plug in UUT; Turn Main Power switch ON. LED’s on the front panel may be either Red or Green. Turn VOLUME control full clockwise. Low Pass control should be set fully clockwise (150Hz).

4. LED should turn Green; immediately bass response should be heard and felt from port tube opening.

5. Turn off generator, turn VOLUME control fully counterclockwise, disconnect RCA cables.

6. Connect one pair of speaker cables to either high level input terminal on UUT. Cables should be connected to an integrated amplifier fed by the signal generator.

7. Turn on generator and adjust so that speaker level output is 1.0V, 50Hz. Tu rn VOLUME control full clockwise.

8. Green LED should light, immediate bass response should be heard and felt from the port tube opening.

Sweep Function

1. Follow steps 1-4 above, using a sweep generator as a signal source.

2. Sweep generator from 20Hz to 300Hz. Listen to the cabinet and drivers for any rattles, clicks, buzzes or any other noises. If any unusual noises are heard, remove driver and test.

Driver Function

1. Remove driver from cabinet; detach + and – wire clips.

2. Check DC resistance of driver; it should be 4.8 ohms.

3. Connect a pair of speaker cables to driver terminals. Cables should be connected to an integrated amplifier fed by a signal generator and adjust so that speaker level output is 5.0V.

4. Sweep generator from 20Hz to 1kHz. Listen to driver for any rubbing, buzzing, or other unusual noises.

CD PLAYER

PRE AMP

AMPLIFIER

AC VOLT

SPEAKER

LEVEL

METER (6V)

LINE LEVEL

UNDER TEST

FROM

LINE-LEVEL

SOURCE

PB12

SPEAKER

OUTPUT

FROM

AMPLIFIER

LEVEL

Min Max

PHASE

CROSSOVER FREQUENCY

50 Hz 150 Hz

PowerBass PB12

LINE LEVEL IN

FOR LFE USE L or R

LFE

NORMAL

180

HIGH LIVEL

IN R

HIGH LIVEL OUT

00229

PB12

Service Bulletin

Service Bulletin JBL2001-03 Rev1 – January 2002 This is considered a Minor repair

To: All JBL Service Centers

Models: PB10, PB12 (Revision 1 only)*

Subject: Unit Will Not Switch to Standby Mode

When the power cord of the PB series subwoofer is plugged into a wall outlet (and for the PB12 only, the power

switch is on), and an audio signal is present, the LED’s on the cabinet face will turn green, indicating the

subwoofer is in the ON mode. With the audio signal removed, it will take 10 - 15 minutes for the LEDs to turn

from green to red, indicating the subwoofer is now in the STANDBY mode. Power consumption is minimal in this

mode.

In the event you receive a PB10 or PB12 subwoofer with the complaint: “The unit will not switch to

standby mode, even when the audio signal is removed” (indicated by the subwoofer’s green LED’s

remaining on), perform the following modification:

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 turned and supported correctly, no other

connectors need to be unplugged.

4) Locate Zener Diode D10 and Resistor R42 (22kΩ). See illustration. These parts must be “swapped”, i.e.,

R42 soldered into the D10 location, and D10 soldered into the R42 location. VERY IMPORTANT: Observe

polarity on D10 in new location.

5) Replace amplifier; test subwoofer to assure the unit goes into the standby mode 10 - 15 minutes after

removing the Audio input signal.

Mode l S e r i al num be r S ta tus Ac ti on

PB10 *

PB12 *

Al l ser i al number s

af f ect ed

Unit may not switch to Standby mode

Swap locations:

Zener Diode D10,

Resistor R42 (22kΩ).

Observe D10 polarity.

* Revision 1 of the PB10/12: Amplifier faceplate says “Made in Canada”; Amplifier serial number starts with “AM”

Black (or silver) potted, non-serviceable S53/64AMI output module. PB10 only – No Power switch

PB12

Service Bulletin

Service Bulletin JBL2001-04 Rev1 – January 2002 This is considered a Minor repair

To: All JBL Service Centers

Models: PB10, PB12 (Revision 1 only)*

Subject: Hum, Buzz or “Thumping”

In the event you receive a PB10 or PB12 subwoofer complaint: “There is an audible hum or buzz”, or the subwoofer

“thumps” or “pops” every 10 seconds, then review the conditions below to determine the most effective solution:

A) Audible Hum with unit on, Green LED is ON, hum disappears completely when the connecting input cables (RCA or

Speaker-Level) are disconnected:

Very long runs of line-level input cables, particularly in parallel with AC power cords, may induce hum in the audio

cables. Check audio cables for defects, broken ground connections, or replace low quality cables. Try plugging the

AC power cord from the subwoofer into a different AC service outlet other than the outlet the rest of the audio

equipment is plugged into.

B) Mild Audible Hum under all circumstances when power cord is plugged in outlet. Hum level does not change whether the

LED’s are Red or Green, or input cables are connected or disconnected. Level control adjustments do not change the

hum level.

This is a mechanical hum caused by the power transformer. Note that a slight hum, within design limits, may be

noticeable in a very quiet room, when you are close to the unit. This is acceptable within the PB10’s product and

price category to most customers, but not to others. If the mechanical hum is unacceptable to the customer, then

replace Power Transformer. PB10: JBL part# 80135. PB12: JBL part# 80116

C) Loud Hum, under all circumstances. It may be louder when LED’s are Green vs. Red ; it may be affected by the position

of the Level control. The subwoofer may “thump” or “pop” approximately every 10 seconds.

Reset the digital subwoofer amplifier by unplugging the AC power cord. Wait 30 seconds, then plug the cord back in.

Repeat this 2-3 times if necessary.

For #C only - If the unit still does not function correctly, then replace Power Amp Module S53/64AMI as per

instructions below: PB10: JBL part# 60301 PB12: JBL part# 60302

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 the Power Amp Module S53/64AMI, see location on the following page. It is the large black or gray component

with a metal case. On the solder side of the circuit board are 28 soldered connections. NOTE: See special handling

instructions for S53/64AMI on the following page.

5) Replace the amplifier assembly back into the cabinet; replace the screws.

6) Test the unit and confirm the original problem has been corrected. NOTE: THE PB10/12 REVISION 1 AMPLIFIER

MUST ALWAYS BE TESTED WITH A WOOFER OR 4 OHM RESISTIVE LOAD.

MODEL Ser i al Number (120v)

Serial numbers are located on the cabinet directly

PB10 See ser i al number s on Page 3 for fac t o r y

PB12 Hum, Buzz or “Thumping” Repl ac e Power Amp Modul e S64AMI

* Revision 1 of the PB10/12: Amplifier faceplate says “Made in Canada”; Amplifier serial number starts with “AM”

below the amplifier faceplate.

Hum, Buzz or “Thumping” Repl ac e Power Amp Modul e S53AMI

modi fi ed uni t s

STATUS ACTI ON

for symptoms described in #C only

Black (or silver) potted, non-serviceable S53/64AMI output module. PB10 only – No Power switch

PB12

+6V 15

V+

1 +6V

V+3

O/P

19 5

O/P

V- V-

21 7

SD 24

+15V 23 9 +15V

10 SD

FR 25 11 FR

I/P 26 12 I/P

GND 27 13 GND

-15V 28 14 -15V

00228

NOTE: THE FOLLOWING PROCEDURES MUST BE FOLLOWED WHEN INSTALLING NEW S53AMI/S64AMI AMP MODULES:

FAILURE TO FOLLOW ONE OR MORE OF THESE STEPS MAY RESULT IN THE INSTANT DESTRUCTION OF THE MODULE WHEN POWERED UP.

1. Align white indent marker on Amp Module with indent marker on main PCB; alternately observe position of label on top of the Module; incorrectly replacing the Module 180° in the PCB slot will result in its destruction.

2. All AC powered test instruments (meters, oscilloscopes, etc.) must have a floating ground, i.e., be connected to an isolation transformer.

3. Align and position the Amp Module before soldering.

4. Attach the Amp Module with the mounting screws before soldering or powering up.

5. Use only rosin-core or non-acid core solder; thoroughly de-flux the surfaces after soldering.

If the new S53AMI/S64AMI Amp Module has larger mounting hole(s) in the case, and the stock screws no longer will fit, and screws of the proper type cannot be obtained locally order:

(2) part# 60301S (screws)

(2) part# 60301N (nuts)

S53AMI/S64AMI - Power Amp Module SAFETY PART

PB10/12 Revision 1 Only

PB12

Service Bulletin

Service Bulletin JBL2001-05 Rev2 - February 2002 This is considered a Minor repair

To: All JBL Service Centers

Models: PB12 (Revision 1 only)*

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.

Model Serial number (120V) Status Action

PB12 * AM0035-24318 and below L1 may be damaged

if experiencing above symptoms

PB12 * AM0035-24319 and above Modified by factory None required

* Revision 1 of the PB12: Amplifier faceplate says “Made in Canada”; Amplifier serial number starts with “AM”

Black (or silver) potted, non-serviceable S64AMI output module.

Replace L1

with JBL part# 80121

PB12

Service Bulletin

Service Bulletin JBL2001-07 Rev1 - February 2002 This is considered a Minor repair

To: All JBL Service Centers

Model: PB12 (Revision 1 only)*

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.

* Revision 1 of the PB12:

Amplifier faceplate says “Made in Canada”; Amplifier serial number starts with “AM”

Black (or silver) potted, non-serviceable S64AMI output module.

+ 37 hidden pages

JBL PB-12 Mk3 Service manual

Specifications and Main Features

Frequently Asked Questions

User Manual