Kdl46ex723bu sound but no picture

[wreksta]

hi all me again lol my parents just rang their expensive set has went down

its a KDL46EX723BU

APPERENTLY IT HAS SOUND BUT THIS CRACKLES ON SOME SOURCE INPUTS

AND PERFECT ON OTHERS

BUT NO PICTURE AT ALL

ANY POINTERS BEFORE I TAKE A DRIVE OVER AND LOOK

[truep]

Re: Kdl46ex723bu sound but no picture

Ask if there is a faint glow on the screen (backlight). that's a start. If so, it may be a TCON, or a main board fault.
If not see if you can see a picture with a flashlight.

[tom66]

Re: Kdl46ex723bu sound but no picture

Check backlight: no backlight, if so, check inverter power (maybe HV design, don't use your meter!); if backlight, t-con or main. Check t-con fuse, power rail. Check LVDS seated. Investigate if crackling affects both HDMI and analog or only one or the other.

[wreksta]

Re: Kdl46ex723bu sound but no picture

Tom how to tel hv design and then what to do im on my way over there soon

[wreksta]

Re: Kdl46ex723bu sound but no picture

tom its got worse there now a flashing light no power

[tom66]

Re: Kdl46ex723bu sound but no picture

Count blinks between each pause - probably backlight error.
HV design: no 24V for inverters, big high voltage cables.

[wreksta]

Re: Kdl46ex723bu sound but no picture

Hi tom when I checked the set out there was 4 blinking led so removed back and set about fault finding tcon making s constant ticking noise no backlight and red blink 4 times disconneced all boards and jumped ps on and 3.3 volt standby then measured the set I got most voltages as per label but was getting 0v on two tcon 12v vcc and 0v on tcon
Tcon vcc tob I have all my readings wrote down do will update shortly my question should there be 12v on the 12v vcc at all timed PSU fires up and would this cause ticking on tcon board and no back light

[tom66]

Re: Kdl46ex723bu sound but no picture

If you jumpered PS ON that SHOULD bring up 12V for t-con. However check if there is also a POWER LCD or POWER TCON signal or similar, which may be used to control T-con power separately.
If the TV goes to a blink error, because there is a missing voltage, then you won't get any backlight as the main processor is shutting it off.

[wreksta]

Re: Kdl46ex723bu sound but no picture

Well we had lightning when set went dodgy they had no powercut though I suspect bad power board but what causes tcon to tick tick tick tick constantly I had 12v on both sides of both tcon fuses with all boards attatched but with power board running jumped tcon vcc 0v,s

[tom66]

Re: Kdl46ex723bu sound but no picture

You have 12V to t-con normally, no jumper in place?
Disconnect panel ribbons (top of t-con, not LVDS cable) then check if ticking still occurs. If it goes, panel or driver is shorted somewhere which may mean bad LCD panel.

[wreksta]

Re: Kdl46ex723bu sound but no picture

Tom I should have mentioned that I done this also clicking remains without ribbons to panel boards I'm thinking bad PSU or inverter board I also tried with backlight disconnected from inverter board will post some pics and more details when I get home

[wreksta]

Re: Kdl46ex723bu sound but no picture

Tom I should have mentioned that I done this also clicking remains without ribbons to panel boards I'm thinking bad PSU or inverter board I also tried with backlight disconnected from inverter board will post some pics and more details when I get home