NEC MultiSync FP1350 - 5-4.Vertical Position; 5-5.Poor Linearity

7-14
5-4. Vertical Position
5-5. Poor Linearity
5-5-1. Horizontal
5-5-2. Vertical
Check whether the DC voltages level at CN-DSB pin 12 on the DEF
PWB (PWE-568) varies by OSD vertical position control or not?
• IC501 failure.
• Digital control circuit failure. (see item 12)
Check whether the DC voltages level at IC421 pin 8 on the DEF
PWB (PWE-568) varies by OSD vertical position control or not?
• IC401, VDY or their ambient circuit failure.
• IC421 or its ambient circuit failure.
Check if the vertical linearity on the screen varies by OSD "VERTICAL
LINEARITY" and "VERTICAL LINEARITY BALANCE".
• IC501 failure.
• Digital control circuit failure. (see item 12)
Check the D/A converter output. (IC532 pin 4,18,19)
• IC532 or its ambient circuit failure.
• Digital control circuit failure. (see item 12)
• Q421, Q422, Q423 or their ambient circuit failure.
• IC421 or its ambient circuit failure.
0V
V. saw wave
Position down Position up
NG
OK
NG
OK
NG
Check an item 5-1.
OK
T571, Q571, IC591、IC532(pin 17) or their ambient circuit failure.
NG
OK
OK
55 70
90 105
130
160
5V
0V
5V
0V
5V
0V
Vertical frequency (Hz)
pin 4
pin 18
pin 19
Check the voltage at IC532 pin 4,18 and 19.
The output voltages of each pin are as follows.