ViewSonic VLCDS27955-1W Service Manual page 16

FB4/FB7/D33
No
+12V->5V
regulator CKT no
work
ViewSonic Corporation
Use multi-meter to measure
& turn on system
No
Remove
Yes
5V ok ?
+5V short to
GND or 3.3V
NO POWER
D
12V ok ?
Yes
5V ok ?
Yes
3.3V/2.5V
Yes
ok ?
No
MCU 3.3V bad
3.3V/2.5V short
to GND
PC 5V/DC 3.3V
CKT not correct
13
Remove adapter
Measure adapter only
Adapter ok
No
Change adapter
Measure +12V to
GND
Confidential - Do Not Copy
Yes
VG510b/s