MCU
No
Crystal no
OSC
(1)MCU not put well
(2)Crystal bad
(3)Cap of crystal
too big/small
No
MCU 5V
=4.75~5.25V
No
Check DC 5V CKT
Check Reset
waveform when
power on
Check Reset CKT
No
Yes
Check 4 corner are shorted
or not
Change socket
Be carefully when using
probe to measure
No
MCU bad
If input over
MCU 5+0.25V
Yes
No
Not allowed
No
Check if socket
pin bend
Check if MCU
pin short or bend
Yes
Reflow
A pulse to > 4.75V
Check if O/P
short to GND
No pulse
Yes
Yes
Yes
Re-programming
MCU not
programmed
B
Yes
11
ViewSonic
Corporation
Co
nfidential
-
Do
Not
Copy
VG511s
VG512s