JBL LS Series, Service Manual

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- CONTENTS -
BASIC SPECIFICATIONS …………….……..…………..1
DETAILED SPECIFICATIONS ……….……..…………..2
PACKING……..……………………………….….….….....4
CONTROLS/CONNECTIONS………………..…...…..…5
OPERATION ……..………………….……...…….….…...7
EXPLODED VIEW/PARTS LIST…….….….…………....8
TEST SET-UP AND PROCEDURE….….……………....9
AMPLIFIER BLOCK DIAGRAM…….………….……..…10
DETAILED TROUBLESHOOTING..……………… ……12
P.C.B. DRAWINGS….…………………………………….13
ELECTRICAL PARTS LIST ..……….……….……….…18
IC/TRANSISTOR PINOUTS..……..….…….….….….….22
SCHEMATICS…………………………………………….23
LS120P SPECIFICATIONS
Amplifier Power (RMS): 400 Watts
Peak Dynamic Power *: 700 Watts
Driver: 12" (305mm) PolyPlas™
Inputs: Line Level (switchable to LFE)
Low-Pass Frequency: Variable from 50Hz to 150Hz
(24dB/octave, continuously variable)
Frequency Response: 25Hz – 150Hz (or Low-pass crossover setting)
Dimensions (H x W x D): 20-1/16" x 14-3/4" x 17-1/4" (510mm x 375mm x 438mm)
(with feet, controls, grille, etc.)
Weight: 57 lb/25.8kg
JBL continually strives to update and improve existing products, as well as create new ones. The specifications and
details in this and related JBL publications are therefore subject to change without notice.
* The Peak Dynamic Power is measured by recording the highest center-to-peak voltage measured across the
output of a resistive load equal to minimum impedance of the transducer, using a 50Hz sine wave burst, 3 cycles
on, 17 cycles off.
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LS120P