Checking The Back Light Unit - NEC NMV 1700V Service Manual

3. Checking the back light unit

Is +19V supplied to F301 pin 1.
NG
OK
Is +19V supplied to P308 pin 3, 4 to inverter
NG
OK
Check the BKLT_EN signal of the rectangle input I327 pin 3 at TTL high level
NG
OK
Check the PWM signal of the input from I315 pin M4 (R374 pin 2) is a PWM signal.
OK
Failure point
1) Inverter cable disconnection.
2) Inverter of LCD module failure.
Trouble Shooting
Are connected AC adapters normal goods?
PWB?
Failure point
Inverter cable disconnection.
Is a "H" level being output in the TTL level from I306 pin 14
Or, is BKLT_EN signal of the rectangle being output?
NG
Failure point
Printed wire broke between
I306 pin 14 and I327 pin 3.
Failure point
NG
1) Printed wire broke between
I315 pin M4 and R374 pin 2.
2) I315 failure.
NG
An AC adapter is changed to the normal goods.
OK
Failure point
Printed wire broke between
P312 pin 1.
NMV 1700V
Failure point
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