Power Supply Trouble Shooting Chart - ViewSonic P774B-2NT Series Service Manual

6-9 POWER SUPPLY TROUBLE SHOOTING CHART

BEFORE CHECK SW.REG. PLEASE REFER TO THE POWER SUPPLY BLOCK DIAGRAM
POWER SUPPLY OUTPUT: (A)
BEAD SET
CHECK AC LINE
VOLT 120V OR 220V
NG
OK
CHECK LINE RECTIFIED
& SMOOTHED VOLT
NG
OK
CHECK START C.K.T
R939, D912, D911, R930
OK
CHECK T901 O/P
NG
OK
CHECK IC901
VARIABLE OUTPUT : 58V - 145V
(DEPENDING EPENDING UPON H.SYNC FREQUENCY)
(B) CONSTANT OUTPUT : 6.3V, 14V, -12V, 78V
CHECK F901, SW901
CHECK BRIDGE
RECTIFIED CIRCUIT
CHECK 55.5V, 12.3V, 6.3V
CIRCUIT OUTPUT
NG
19
ABNORMAL VARIABLE OUTPUT
MAKE SURE THAT
THE VARIABLE
OUTPUT IS NOT SHORTED
NO
YES
CHECK THE 55.5V
NG
OK
CHECK Q911
NG
OK
IC401 29(ABOUT 11.5V)
OK
CHECK IC401
PIN 14, 15, 16, 28, B+
DRIVER
CHECK D919
Q911 FAILURE