NEC MultiSync 2A Service Manual page 23

2. ABNORMAL VIDEO ON CRT SCREEN
CHECK
R,G,B
VIDEO OUTPUT
MEASURE THE VOL TAG ES POINTS TP701 , TP702, TP703 ON THE CRT PWB
PWE-243B
OK
CHECK G1 VOLTAGE
NG
OK BLANKING CIRCUITRY
CONNECTOR D2-C5
CRT SOCKET
BRIGHTNESS CIRCUITRY
FAILURE
TURN THE SCREEN VA
CLOCKWISE
TOO LOW
SOCKET FAILURE
TOO BRIGHT
TOO DARK
NG
1 00V LINE
OK
1 2V LINE
OK
CHECK IC701
OUTPUT
OK
VIDEO OUTPUT CIRCUITRY FAILURE
-21 -
MEASURE THE VOLTAGE
BETWEEN C5-1 AND C5-8
NG
1 00V REG CIRCUITRY
CONNECTOR D2-C5
FAILURE
MEASURE THE VOLTAGE
BETWEEN C5-3 AND C5-8
NG
CONNECTOR D2-C5
FAILURE
MEASURE THE VOLTAGES
21 , 25 AND 29 PIN O F
IC701
NG
CIRCUITRY CONTRAST
CONTROL CIRCUITRY
FAILURE