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Powered Subwoofer

BASS20

TEST PROCEDURE

Equipment Needed:

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Function generator/signal generator/sweep generator

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Integrated Amplifier

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Multimeter

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Cables - Line level (RCA) and Speaker cables

UUT = Unit Under Test

General Function

1. Connect both left and right line level inputs (RCA) to signal generator and UUT. Use Y-cable if necessary

from mono source.

2. Turn on generator and adjust to 100mV, 50 Hz.
3. Plug in UUT; red LED should be ON. Turn power switch to the ON or AUTO position and turn LEVEL control

full clockwise.

4. Green LED should light, immediate bass response should be heard and felt from port tube openings.
5. Turn off generator, turn unit to OFF, disconnect RCA cables.

6. Connect two pairs of speaker cables to high level input terminal on UUT. Cables should be connected to an

integrated amplifier fed by the signal generator. Observe polarity of speaker cables.

7. Turn on generator and adjust so that speaker level output is 2.5V, 50 Hz.

8. Turn power switch to the ON or AUTO position and turn LEVEL control full clockwise.

9. Green LED should light, immediate bass response should be heard and felt from 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 noises are heard, remove driver and test.

Driver Function

1. Remove one or both drivers from cabinet;  and - wire clips.
2. Check DC resistance of driver; it should be 4.2 ohms.
3. Connect a pair of speaker cables to driver terminals. Cables should be connected to an integrated amplifier fed

by a signal generator. Turn on 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.

SERVICE NOTE (120v Version only)

Even though the Bass20 seems to have an on/off power switch, in fact the switch does not

switch the main power off to the amp assembly, even in the OFF position. All AC and DC

voltages within the amplifier are still active, so for safety concerns the AC power cord should

be unplugged before any servicing begins.

All manuals and user guides at all-guides.com

Summary of Contents for JBL Bass 20

Page 1: ...ed Subwoofer JBL Consumer Products Inc 80 Crossways Park West Woodbury N Y 11797 1 800 336 4JBL in the USA A Harman International Company Part No 1112 JBLBASS20 BASS20 All manuals and user guides at all guides com a l l g u i d e s c o m ...

Page 2: ...peaker Level Outputs Full Range Speaker Crossover Frequency 120Hz Frequency Response 40Hz 120Hz 3dB External Dimensions Inches Height 17 3 4 Width 10 Depth 24 External Dimensions mms Height 451 Width 254 Depth 610 Weight 42lbs 19 1kg FEATURES n The Bass20 powered subwoofer is part of the SCS120 or MUSIC 20 System n 150 watt output n Variable level control n Line level or Speaker level inputs outpu...

Page 3: ...finements are introduced into existing models without notice as a routine expression of our design philosophy For this reason Bass Series loudspeakers may differ in some respect from their published specifications and descriptions but will always equal or exceed the original specifications unless otherwise stated All manuals and user guides at all guides com ...

Page 4: ...EVEL control full clockwise 9 Green LED should light immediate bass response should be heard and felt from 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 noises are heard remove driver and test Driver Function 1 Remove...

Page 5: ...s Circuit board does not have to be removed from heatsink 2 R36 See drawing cut trace connecting Q4 collector and main C1 pad 3 Create solderable surface on PCB on Q4 side of cut by scraping the green mask from board with Exacto knife or similar tool 4 Attach R36 470Ω 1W resistor JBL RS2180 to new surface and cathode side of CR1 Resistor should stand off from PCB secure with RTV or epoxy if desire...

Page 6: ...5 Powered Subwoofer BASS20 BASS 20 120v US 230v European Versions BLOCK DIAGRAM All manuals and user guides at all guides com a l l g u i d e s c o m ...

Page 7: ...6 Powered Subwoofer BASS20 BASS20 120V 230V versions AMPLIFIER EXPLODED VIEW All manuals and user guides at all guides com ...

Page 8: ...7 Powered Subwoofer BASS20 BASS20 CABINET ASSEMBLY EXPLODED VIEW All manuals and user guides at all guides com ...

Page 9: ...M EL 22uF 20 16V P 4 C11 CP1178 CAP POLY FILM 22nF 5 63V P 1 REF NO PART NO DESCRIPTION QTY C14 16 CP1426 SMD CAP 0 1uF 20 50V Z5U P 2 C15 CP1479 SMD CAP 3300pF 10 100V X PI 1 C19 28 CP1645 CAP AL EL 22uF 20 63V 85 PI 2 C21 CP1478 SMD CAP 330pF 5 100V NPO P 1 C22 CP1475 SMD CAP 33pF 5 50V NPO 12 P 1 C23 CP1411 CAP ALUM EL 100uF 20 16V P 1 C1P CP1426 SMD CAP 0 1uF 20 50V Z5U P 1 C2P C3P CP1480 SMD ...

Page 10: ...r Voltage To 140v 6 19 96 2 R11 changed from 27K to 51K R12 changed from 51K to 24K R9 changed from 20K to 200K R10 changed from 33K to 200K R29 changed from 11K to 33K R51 changed from 160K to 470K R39 changed from 47K to 10K R54 changed from 47K to 10K R22 changed from 15K to 4 7K R34 changed from 15K to 4 7K R20 changed from 220 to 160 R40 changed from 220 to 160 R33 changed from 4 3K to 4 7K C...

Page 11: ...1 0 Powered Subwoofer BASS20 BASS20 PACKAGING VIEW MUSIC20 SCS120 All manuals and user guides at all guides com a l l g u i d e s c o m ...

Page 12: ...1 1 Powered Subwoofer BASS20 PRINTED CIRCUIT BOARDS TOP VIEW All manuals and user guides at all guides com ...

Page 13: ...1 2 Powered Subwoofer BASS20 PRINTED CIRCUIT BOARDS BOTTOM VIEW All manuals and user guides at all guides com ...

Page 14: ...1 3 Powered Subwoofer BASS20 INTEGRATED CIRCUIT DIAGRAM All manuals and user guides at all guides com ...

Page 15: ...1 4 Powered Subwoofer BASS20 120V SCHEMATIC DIAGRAM All manuals and user guides at all guides com ...

Page 16: ...1 4 Powered Subwoofer BASS20 120V SCHEMATIC DIAGRAM All manuals and user guides at all guides com a l l g u i d e s c o m ...

Page 17: ...1 5 Powered Subwoofer BASS20 230V SCHEMATIC DIAGRAM All manuals and user guides at all guides com ...

Page 18: ...1 5 Powered Subwoofer BASS20 230V SCHEMATIC DIAGRAM All manuals and user guides at all guides com ...

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