JBL Detailed Troubleshooting Contd, E250P/P12SW subwoofers, High Level Input Sensitivity, Lfe

E250P/P12SW subwoofers

DETAILED TROUBLESHOOTING (CONT'D)

- Voltage measurements

OP AMP

SPEAKER

U2(1)

U2(14)

U2(8)

U3(7)

U3(1)

U3(14)

U3(8)

U5(7)

U5(1)

O/P

306.9mV

461mV

460mV

658mV

628mV

598mV

2.326V

2.02V

3.57V

23.33V

2. High Level Input Sensitivity

-Set up

Turn level, X’OVER FREQ POT Fully CW and LFE switch off

Set Generator at 1.3V@50Hz

Signal to High level input

-Voltage measurements 15.3V at speaker output

3. Low-Pass

-Set up

Set Generator at 200 mV@100Hz

Signal to Line level input

Measure voltage at S+ speaker output

-Voltage measurement

X’OVER FREQ. Setting

Output

CW

14.03V

CCW

4.8V

4. LFE

-Set up

Set Generator at 200mV@200Hz

Signal to Line level input

Measure voltage at S+ speaker output

LFE

switch Setting

Output

Normal

6V

LFE

18.32V

See flow chart next page for diagnostics.

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