Osd Circuit - LG DC593W Manual

(3) KEY doesn't working
KEY doesn't working.
Is 5V applied to the IC501
Pin 15?
YES
Does LED or FLD change
when a function button is
pressed?

4. OSD CIRCUIT

(1) No OSD display.
No OSD display.
Is 5.3V applied to the
IC501 Pin42?
YES
Does oscillation occur at
the IC501 Pins52, 53?
YES
Does oscillation occur at
the IC501 Pins50, 51?
YES
Replace the IC501.
(2) No F.OSD display.
No F.OSD display.
Refer to "(1) No OSD
display".
YES
Does the C.SYNC signal
appear at the IC501 Pin87?
YES
Replace the IC501.
NO
Refer to "SMPS 5.3VA
Trouble Shooting".
NO
Replace the defective
switches.
NO
Refer to "SMPS 5.3VA
Trouble Shooting".
NO
Is the oscillation input to
Q501 base?
Check or Replace the
NO
Peripheral Circuitry. (L506,
R517, C519, C518, R518)
(3) I 2 C BUS CHECK
The I 2 C waves don't
come out.
Does Power appear at the
Pull up impedence
(R508, R510)?
YES
NO
Replace the IC501.
Refer to "AVCP. C. Sync.
Trouble shooting".
3-9
Check whether X301
oscillates
NO
YES
Check or Replace the
Peripheral Circuitry. (L506,
R517, C519, C518, R518)
NO Refer to "SMPS 5.3VA
Trouble Shooting".