JBL Detailed Troubleshooting, E250P/P12SW subwoofers, A. Power Amp Section, Power Up LED RED

E250P/P12SW subwoofers

DETAILED TROUBLESHOOTING

A. Power Amp Section

Resistance	Resistance from S+ (SPK O/P) to GND should be >1M Ω (NO LOAD)
Check
	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

2. Power Up LED RED

With a 5mV signal to Low level input, LED should change to GREEN

-Voltage measurements (DVM)

OP AMP

LED

P-U4(1)

P-U4(7)

RED

0Vrms

11.84VDC

GREEN

7.13Vrms

-12.93VDC

3. D.C. Operation

-Voltage measurements (DVM) on CLASS D POWER AMP

Between

V+

Q4(E)

Q1(C)

Q10(C)

U7(1)

U7(2)

U7(4)

U7(6)

U7(7)

U7(8)

And This

GND

V-

GND

GND

GND

GND

GND

GND

GND

GND

Point

Get this

71.7V

0V

-71.7V

0V

-71.7V

-71.5V

-71.2V

0V

0V

4.65V

Reading

4. Check Switching Frequency

•Oscilloscope - USE THE PROBE TIP TO U6(7) TO GND

•Reading 100kHz +/-10%,24Vp-p

B. Pre Amp Section

Line Level Input Sensitivity

-Set up	Turn level, X’OVER FREQ POT Fully CW and LFE switch off
	Generator Set at 200mV@50Hz
	Signal to Line level input

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