ViewSonic G90fB-4 - Troubleshooting Flow Chart; Raster and DDC Issues

6. Trouble Shooting Flow Chart
6-1. No raster,CRT relative circuit problems
NG
OK
NG
NG
OK
NG
OK
NG
OK
NG
OK
OK
6-2. Abnormal DDC (Plug & Play)
O
K
N
G
CHECK IC101 PIN 16 VOLTAGE ABOUT 5V
CHECK SIGNAL CABLE
CHECK IC902 GOOD OR FAIL
OR H802 PIN 2
,
4 DATA OUTPUT
CHECK MAIN BOARD POWE
R
SUPPLY: 12V, 180V, 83V, -12V, 6.3V
PLEASE CHECK HIGH VOLTAGE OF
CRT ABOUT 25.5~26.5KV
PLEASE CHECK POWER SAVING
CIRCUIT OR POWER SUPPL
Y
CIRCUIT.
ENTER POWER OR POWER CIRCUIT
FAIL.
CHECK THE HEATER VOLTAGE AT
CRT SOCKET ABOUT 6.3V
CHECK THE 6.3V SUPPLY CIRCUIT:
Q906,ZD902
CHECK THE CIRCUIT OF PIN 18/20 OF
IC101
CHECK G2 VOLTAGE ABOUT 550~650V CHECK FBT
CHECK THE G1 VOLTAGE ABOUT –16
V
AT BRIGHTNESS MAX
CHECK THE G1 CONTROL CIRCUIT:
Q705 RELATIVE CIRCUIT
CHECK THE CATHODE VOLTAGE
ABOUT 60V
CRT FAIL
ViewSonic Corporation Confidential - Do Not Copy G90fB-4
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