5-7.Poor Focus - NEC MultiSync FP1370 Service Manual

5-7. Poor Focus
Adjust Focus VR on FBT. (F1 and F2)
Focus is poor all over the screen.
Focus performance is different at center and other parts of the screen.
Check the dynamic focus voltage at TP-DF.
H. Dynamic focus voltage is approx. 580Vp-p.
V. Dynamic focus voltage is approx. 170Vp-p.
H is NG.
Check the waveform at CN-DSB pin 1.
.
NG
Check the waveform at IC513 pin 5.
OK
IC513 or its ambient circuit failure.
NG
･IC501,R501 or C501 failure.
･Digital control circuit failure. (See item 12)
OK
Check the waveform at CN-DF pin 3.
NG
Q951 or its ambient circuit failure.
OK
Q981~Q985, T981 or their ambient
circuit failure.
FBT, focus lead, CRT socket or CRT failure.
V is NG.
Check the waveform at CN-DSB pin 2.
NG
Check the waveform at IC510 pin 10.
NG
･IC501,R527 or C520 failure.
･Digital control circuit failure. (See item 12)
OK
Check the waveform at CN-DF pin 4.
NG
DEF PWB pattern failure.
OK
Check the Q5X1 Emitter voltage and
confirm the voltage approx. -80V.
NG
OK
Q987, T981 or their ambient circuit failure.
7-16
OK
IC510 or its ambient circuit failure.
Q5X1, Q5X2 or their ambient
circuit failure.