Zenith XBV 443, Service Manual

Page: 19 / 108

3-10
4. OSD CIRCUIT
(1) No OSD display.
(2) I
2
C BUS CHECK
KEY doesn’t working.
Is 5V applied to the IC501
Pin99?
Does LED or FLD change
when a function button is
pressed?
No OSD or F.OSD display.
Is 5.3V applied to the
IC501 Pin53?
Does oscillation occur at
the IC501 Pins44, 45?
Replace the IC501.
The I
2
C waves don’t
come out.
Does Power appear at the
Pull up impedence
(R569, R507)?
Replace the IC501.
Refer to “SMPS 5.3VA
Trouble Shooting”.
Replace the defective
switches.
Refer to “SMPS 5.3VA
Trouble Shooting”.
Check or Replace the phe-
ripheral Circurity.(L511,
R518, C596, C595)
Refer to “SMPS 5.3VA
Trouble Shooting”.
YES
YES
YES
YES
NO
NO
NO
NO
NO
2. SERVO CIRCUIT
(4) KEY doesn’t working