H Osc / Def / Hv Circuit Failure - NEC MultiSync FP1350 Service Manual

6. H OSC / DEF / HV CIRCUIT FAILURE

Check the horizontal drive pulse.
OK
Check the waveform of IC592 pin 3.
OK
Check the waveform of gate at Q5G1.
OK
Check the voltage for horizontal drive circuit.
OK
Check the AFC pulse at R5E1.
OK
Check high voltage.
CONTINUE1 CONTINUE2
Check the drive pulse at CN-DSB pin 10 on the DEF PWB (PWE-
568) outputs a rectangle waveform which amplitude is 4.3Vp-p.
NG
IC592 or its ambient circuit failure.
NG
Q5G1, ZD5G1, D5G2 or their ambient circuit failure.
Note: Q561, Q5G1 and Q5A1 will short out at the same time.
NG
R557 failure
NG
Q555, Q561, T551, T561 or their ambient circuit failure.
Measure the CRT anode voltage.
Normally, high voltage is approx. 27kV.
NG
Check 80V line.
CONTINUE3
Normally, it is sawtooth wave which amplitude is
approx. 5Vp-p.
Be sure to get the L5G2 off the DEF PWB, and
output as following.
Horizontal period
Measure the voltage at Q553 collector.
Normally, it is approx. 15V.
Normally, its amplitude is approx. 50Vp-p~60Vp-p.
Measure the voltage at CN-P pin 3 on the SW/HV PWB
(PWE-571).
7-20
approx. 220V