Power No Work Troubleshooting; Dc/Dc Converter - BenQ G2420HD Product Service Manual

5.6.4 Power no work troubleshooting

5.6.4.1 DC/DC converter

DC/DC
converter
Check L852, Q852, FD852, FD853, Q855,
(L851, Q851, FD851, Q853, Q854)
Panel or I/F
BD or Audio
no function
+5V(+5.4V) valid?
No
Q856
OK?
IC
Check IC851
Vcc valid?
No
Check F851
OK?
Yes
AC/DC converter
- 55 -
Check wire and I/F
Yes
BD
No Replace components
Check IC851 pin1
frequency, DTC,
Yes feedback
OK?
No Replace F851
Replace IC851
No
components