JBL Northridge E150P Service Manual page 15

E150P
DETAILED TROUBLESHOOTING (CONT'D)
- Voltage measurements
U2(1) U2(14)
133.6mV 200.2mV
2. High Level Input Sensitivity
-Set up
-Voltage measurements 15.3V at speaker output
3. Low-Pass
-Set up
-Voltage measurement
X'OVER FREQ. Setting
CW
CCW
4. LFE
-Set up
LFE switch Setting
Normal
LFE
See flow chart next page for diagnostics.
OP AMP
U2(8) U3(7)
245.9mV 314.8mV
Turn level, X'OVER FREQ POT Fully CW and LFE switch off
Set Generator at 1.15V@50Hz
Signal to High level input
Set Generator at 100 mV@100Hz
Line
Signal to level input
Measure voltage at S+ speaker output
Output
10.72V
2.165V
Set Generator at 100mV@200Hz
Line
Signal to level input
Measure voltage at S+ speaker output
Output
7.62V
U3(1) U3(14) U3(8)
314.9mV 350mV 1.67V
2.9V
14
SPEAKER
U5(7) U5(1)
1.452V 2.098V
O/P
15.3V