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JBL E150 Service Manual

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Page 11

E150P               
 
TEST SET-UP AND PROCEDURE 
 
 
General Function 
UUT = Unit Under Test 
 
1)  Connect one line level input cable (RCA) from signal generator to either Right or Left Lev el input on UUT. LEVEL 
control should be full counterclockwise (MIN).  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  top panel may be either Red or Green. Turn LEVEL control 
full clockwise...

Page 12

E150P              
 
11

Page 13

 
 
 
 
         TECH TIPS 
 
Troubleshooting tips and solutions to common service problems 
 
For models: E150P,E250P and PB10,PB12 (Revision 2) *    TIP# JBLTT2003-04 Rev1 
  
Subject:  Replacing MOSFETS Q18, Q22  
In the event you need to replace MOSFET transistors Q18 or Q22 as part of a repair, it is important to use 
ONLY the JBL part# FE106401110  or only the brands: International Rectifier, or Fairchild.  
Replace both Q18 and Q22 MOSFET’s in the circuit, even if only one seems to be damaged....

Page 14

$Page 14 A. Power Amp Section Resistance Check Resistance from S+ (SPK O/P) to GND should be >1M Ω (NO LOAD) Resistance from V+ (C6 P+) to V- (C8 P-) gradually Fully CHARGED sho\ uld read >10k Ω Resistance from V+ (C6 P+) to S+ (SPK O/P) should read >1MΩ Resistance from V- (C8 P-) to S+ (SPK O/P) should read >1M Ω 2. Power Up LED RED With a 5mV signal to Low level input, LED should change to GREEN -Voltage measurements (DVM) OP AMP LEDP-U4(1) P-U4(7) RED 0Vrms 8VDC GREEN 6.3Vrms -10.7VDC 3. D.C....$

A.  Power Amp Section
Resistance
Check
Resistance from S+ (SPK O/P) to GND should be >1M Ω (NO LOAD)
Resistance from V+ (C6 P+) to V- (C8 P-) gradually Fully CHARGED sho\
uld read >10k  Ω
Resistance from V+ (C6 P+) to S+ (SPK O/P) should read >1MΩ
Resistance from V- (C8 P-) to S+ (SPK O/P) should read >1M Ω
2. Power Up LED RED
      With a 5mV signal to Low level input, LED should change to GREEN
     -Voltage measurements (DVM)
OP AMP
LEDP-U4(1) P-U4(7)
RED 0Vrms 8VDC
GREEN 6.3Vrms -10.7VDC
3. D.C....

Page 15

 - Voltage measurementsOP AMP
U2(1) U2(14) U2(8) U3(7) U3(1) U3(14) U3(8) U5(7) U5(1) SPEAKER
O/P
133.6mV 200.2mV 245.9mV 314.8mV 314.9mV 350mV 1.67V 1.452V 2.098V 15.3V
2. High Level Input Sensitivity
     -Set up Turn level, X’OVER FREQ POT Fully CW and LFE switch off
                              Set Generator at 1.15V@50Hz Signal to High level input
     -Voltage measurements 15.3V at speaker output
3. Low-Pass
    -Set up Set Generator at 100 mV@100Hz Signal to 
Line level input
Measure voltage at...

Page 16

$Page 16 CAUTION : SPEAKER OUTPUT IS FLOATING AND IS NOT PROTECTED AGAINST A SHORT TO GROUND. ALL TEST INSTRUMENTS CONNECTED T\ O THE OUTPUT MUST BE FLOATING. ATTACH THE SCOPE PROBE TIP \ TO S - and REFERENCE LEAD TO S+. (A 10mV signal may n\ eed from the input to trigger the Switch turn on) \...$

CAUTION : SPEAKER OUTPUT IS FLOATING AND IS  NOT  PROTECTED AGAINST A SHORT
                           TO  GROUND.  ALL TEST INSTRUMENTS CONNECTED T\
O THE OUTPUT  MUST
                           BE  FLOATING.  ATTACH  THE  SCOPE  PROBE TIP \
TO S - and  REFERENCE
                           LEAD TO S+.
                                                   (A 10mV signal may n\
eed from the input to trigger the  Switch turn on)
                                                                        \...

Page 17