Detailed Troubleshooting; Power Amp Section; Power Up Led Red; D.c. Operation - JBL Northridge E-Series E150P Service Manual

E150P/P10SW subwoofers

DETAILED TROUBLESHOOTING

A. Power Amp Section
Resistance
Check

2. Power Up LED RED

With a 5mV signal to Low level input, LED should change to GREEN
-Voltage measurements (DVM)
LED
RED
GREEN

3. D.C. Operation

-Voltage measurements (DVM) on CLASS D POWER AMP
Between V+
And This
GND
Point
Get this
45.9V
Reading
4. Check Switching Frequency
•
Oscilloscope - USE THE PROBE TIP TO U6(7) TO GND
•
Reading 100kHz +/-10%,22Vp-p
B. Pre Amp Section
Line Level Input Sensitivity
-Set up
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 should 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
OP AMP
P-U4(1)
0Vrms
6.3Vrms
Q10(C)
Q4(E) Q1(C)
V- GND GND
0V -45.9V
Turn level, X'OVER FREQ POT Fully CW and LFE switch off
Generator Set at 100mV@50Hz
Signal to Line level input
P-U4(7)
8VDC
-10.7VDC
U7(1) U7(2)
GND GND
0V -45.9V -45.7V
17
U7(4) U7(6) U7(7)
GND GND GND
-45.5V 0V 0V
U7(8)
GND
4.7V