ViewSonic VG181 - Page 44

Service Manual
VG181
TROUBLE SHOOTING
TROUBLE WITH THE DC-DC CONVERTER
No The voltage is about +12V
1. Check power adaptor
2. Check power cable connection
Val
Yes
The voltage is about +12V while
No power switch on
1. JP4 to keypad connection good
2. Check U21 & U20
U20 pin 8
The voltage is about +3.48V
No 1. Check £21, U25 & L23
2. Check ZD3, U26 & U29
3. Adjust VAT
ind
Yes
No The voltage is about +3.48V
1. Chack U27 & U26
Yes
No 1. Cheek C157, C158 & L23
2. Check input of U26
3. Check output frequence of U26
V33 large ripple ?
Page 42
Confidential - Do Not Copy
ViewSonic
July 2000 - Version 1.0