JBL PB-12 Mk3 Service manual

PowerBass™ Series

PB12 Subwoofer

SERVICE MANUAL

JBL, Incorporated

250 Crossways Park Drive

REV 3 5/02

Woodbury, New York 11797

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.

2

PB12

SAFETY INFORMATION

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.

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

3

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 ñ Low-Pass Frequency setting

Line Level (option: LFE); Speaker Level

Speaker level fixed frequency 150Hz

Variable from 50Hz ñ 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 registered trademark of JBL, Incorporated.

4

PB12

DETAILED SPECIFICATIONS PB12 Subwoofer

JBL PB12	250W Powered Sub Amp
LINE VOLTAGE		Yes/No	Hi/Lo Line	Nom.	Unit		Notes
US 120vac/60Hz		Yes	108-132	120	Vrms	Normal Operation
EU 230vac/50-60Hz		Yes	207-264	230	Vrms	Normal operation, MOMS required
Parameter		Specification	Unit	QA Test	Conditions		Notes
				Limits
Amp Section
Type (Class AB, D, other)		D	n/a	n/a
Load Impedance (speaker)		5.6	Ohms	n/a	Nominal
Rated Output Power (120VAC)		250	Watts	140		Domestic version only 120 VAC-60 Hz
Rated Output Power (230VAC)		250	Watts	130		EU Version only	230 VAC-50 Hz
THD @ Rated Power		0.3	%	1	22k filter	145 Watts
THD @ 1 Watt		0.1	%	0.5	22k filter
DC Offset		10	mV-DC	20	@ Speaker Outputs
Damping factor		>50	DF	35	Measured at amplifier board	At spkr cable. 150 Watts @ THD < 0.1 % @ 50 Hz
Input Sensitivity
Input Frequency		50	Hz	50	Nominal Freq.
L&R		240	mVrms	±2dB	To 150 Watts	Single input driven
LFE input		240	mVrms	±2dB	To 150 Watts	Single input driven, LFE switch ON
Speaker/Hi Level Input		2.4	Vrms	±2dB	To 150 Watts	Single input driven
Signal to Noise
SNR-A-Weighted		90	dBA	70	relative to rated power	A-Weighting filter
SNR-unweighted		85	dBr	70	relative to rated power	22k filter
SNR rel. 1W-unweighted		65	dBr	60	relative to 1W Output	22k filter
Residual Noise Floor		1	mVrms	3	Volume @max, using RMS reading	Line level inputs must be terminated using		1KOHM
					DMM/VOM (or A/P) BW=20 Khz.
Residual Noise Floor		1.5	mVrms(max)	3	Volume @max, w/ A/P Swept	Line level inputs must be terminated using		1KOHM
					Bandpass Measurement (Line freq.+
					harmonics) (BW=20 Khz)
Input Impedance
Line Input (L, R,LFE)		20K	ohms	n/a	Nominal
Speaker/Hi Level Input		4.7K	ohms	n/a	Nominal
Filters
LP filter 4th order fixed		60-180	Hz	± 10		2nd order variable + 2nd order fix-24 db/Octave
Subsonic filter (HPF) 3rd Order		Fixed
LFE Low pass 2nd order		200>LP<1K	Hz		LFE input driven only
HP speaker out connector		200	Hz	± 10	Speaker input driven - 4 Ohms
		100	Hz	± 10	Speaker input driven - 8 Ohms
Features		--
Volume pot Taper (lin/log)		LOG	--	functional		A Taper
HP Speaker out		YES		functional		Refer to Filter section
Phase switch		0-180	deg	functional
LP Filter defeat switch		YES		functional		Disables LP filter, intended for LFE
Input Configuration
Line In (L,R) & LFE		YES	--	functional		Dual RCA jack
Spkr/Hi Level In		YES	--	functional		Binding post connector L&R
Signal Sensing (ATO)
Auto-Turn-On (yes/no)		YES		functional
ATO Input test frequency		50	Hz	functional	"
ATO Level LFE Input		4	mV	functional	"	Maximum acceptable level.
ATO Level Speaker in		50	mV	functional	"	Maximum acceptable level.
ATO Turn-on time		5	ms	functional	Amp connected and AC on, then input
					signal applied
Auto Mute/ Turn-OFF Time		15	minutes	15	T before muting, after signal is	Auto turn of time (T)	must be 5 > T < 15 Minutes
					removed
Power on Delay time		3	sec.	4	AC Power Applied
Transients/Pops
ATO Transient		5	mV-peak	n/a	@ Speaker Outputs
Turn-on Transient		50	mV-peak	2v-pp	@ Speaker Outputs	AC Line cycled from OFF to ON
Turn-off Transient		50	mV-peak	2v-pp	@ Speaker Outputs	AC Line cycled from ON to OFF
Efficiency		65	%	64		Nominal Line voltage 120 VAC
Stand-by Input Power		24	Watts	26	@ nom. line voltage	Maximum allowable input power under nominal
						Input voltage and frequency, HOT or COLD
						operation.
Power Cons. @ rated power		234	Watts	240	@ nom. line voltage	150 Watts @ 5.6 Ohms nominal line voltage
Protection
Short Circuit Protection		YES		functional	Direct short at output	Amplifier should resume operation after short circuit
						condition removal
Thermal Protection		YES		functional	@1/8 max unclipped Power at 1.06
					times the input voltage
DC Offset Protection		YES		-	DC present at Speaker Out leads
Line Fuse Rating
USA-Domestic		2	Amps		Type-T or Slo Blo-250 V
EU		1.25	Amps		Type-T or Slo Blo-250 V	External fuse with UL/SEMKO rated holder

5

PB12

PB12 Subwoofer Controls and Their Function

1.	Power - These lights will be red when the unit is	Front Panel
	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	Rear Panel
	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 - Turns the PB12 on or off.

6

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.

7

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 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.

8

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.

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 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.

9

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.

Level Control

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.

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

Min	Max
LFE	NORMAL
PHASE 0º	180º

CROSSOVER

FREQUENCY

50Hz 150Hz

PowerBass PB12

L R

LINE LEVEL IN

For LFE use L or R

L

HIGH

LEVEL

IN

	+	–	R
			L
			HIGH
			LEVEL
			OUT
			R
	ON	OFF	120V
	POWER
			60Hz

PowerBass PB12

CAUTION

RISK OF ELECTRIC SHOCK

DO NOT OPEN

10

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.

11

PB12

PB12 TEST SETUP AND PROCEDURE

AC VOLT

METER (6V)

			LEVEL
	LINE LEVEL	FROM	Min		Max
CD PLAYER		LINE-LEVEL		LFE	NORMAL
		SOURCE	PHASE	0	180
			CROSSOVER
			FREQUENCY
			50 Hz		150 Hz
PRE AMP			PowerBass PB12
	PB12		L	R
	UNDER TEST		LINE LEVEL IN
			FOR LFE USE		L or R
AMPLIFIER					L
					HIGH
					LIVEL
					IN
					R
					L
SPEAKER		SPEAKER			HIGH
					LIVEL
LEVEL		OUTPUT			OUT

FROM	R
AMPLIFIER

00229

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. Turn 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.

12

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.

	Model	Serial number	Status	Action
				Swap locations:
	PB10 *	All serial numbers	Unit may not switch to Standby mode	Zener Diode D10,
	PB12 *	affected		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

13

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	Serial Number (120v)	STATUS	ACTION
		Serial numbers are located on the cabinet directly
		below the amplifier faceplate.
	PB10	See serial numbers on Page 3 for factory	Hum, Buzz or “Thumping”	Replace Power Amp Module S53AMI
		modified units		for symptoms described in #C only
	PB12		Hum, Buzz or “Thumping”	Replace Power Amp Module S64AMI
				for symptoms described in #C only

* 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

14

PB12

PB10/12 Revision 1 Only

S53AMI/S64AMI - Power Amp Module SAFETY PART

+6V

15

1

+6V

NOTE: THE FOLLOWING PROCEDURES MUST BE

FOLLOWED WHEN INSTALLING NEW S53AMI/S64AMI

16

2

AMP MODULES:

FAILURE TO FOLLOW ONE OR MORE OF THESE STEPS

MAY RESULT IN THE INSTANT DESTRUCTION OF THE

V+

17

3

V+

MODULE WHEN POWERED UP.

18

4

1. Align white indent marker on Amp Module with indent

O/P

19

5

O/P

marker on main PCB; alternately observe position of label

on top of the Module; incorrectly replacing the Module

20

6

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

V-

21

7

V-

an isolation transformer.

22

8

3. Align and position the Amp Module before soldering.

+15V

23

9

+15V

4. Attach the Amp Module with the mounting screws before

SD

24

10

SD

soldering or powering up.

5. Use only rosin-core or non-acid core solder; thoroughly

FR

25

11

FR

de-flux the surfaces after soldering.

I/P

26

12

I/P

If the new S53AMI/S64AMI Amp Module has larger mounting

hole(s) in the case, and the stock screws no longer will fit,

GND

27

13

GND

and screws of the proper type cannot be obtained locally

order:

-15V

28

14

-15V

00228

(2) part# 60301S (screws)

(2) part# 60301N (nuts)

15

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	Replace L1
			if experiencing above symptoms	with JBL part# 80121
	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.

16

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.

17