Envision EN7220 Service Manual page 30

4.U4-DATA OUTPUT
Measured DCLK(pin 29 from U401)
DVS, DHS (pin 37,38 from U401 )
Is the waveform ok?
DCLK around 48 MHZ , DVS=60.09Hz , DHS around 80
KHz ?(refer to input signal=640x480@60 Hz 31k, and
LED is Green)
Check MST8111 (U401)
Signal output
(PIN102-103,106-113,118-125,128,1)
Is the waveform ok ?
8.2.2 KEYPAD BOARD
OK
OK
OK
OSD is unstable or not working
Is Key Pad Board connecting normally ?
Y
Is Button Switch normally ?
Y
Is Key Pad Board normally ?
Y
Check Main Board
NG , no transition
Replace MST8111 (U401) or
replace Main board.
If Main Board being replace , please
do the DDC – content reprogrammed
N
Connect Key Pad Board
N
N
Replace Key Pad Board
30
EN7220 Service Manual
Replace Button Switch