LG 47LW6500 LED intermittent

[maxvalutech]

This set starts normally and displays a very good evenly lit picture for 8/10 minutes then LEDs turn off. Turn off set to standby then immediate restart and picture displays again for 3/4 minutes. Watching very closely there is a blink every now and then, very quick, as if LEDs turning off but don't. All voltages on main connector read as per legend when set is going right but also when LEDs go off. The 16 circular test points read 12.5 to 14.3v when set on with no signal, but with a DVD playing they can measure down to half of that - strange? When LEDs off their readings are nominal. The 2 feeds to LEDs show each end pin 57.7v when on with middle pins 13/14v range as for test points. When LEDs are off the end pins drop to around 36v and others are nominal. Because all LEDs are either on or off I'm hoping the problem lies with the power board. TV is edge lit and my experience with LEDs is minimal. Help appreciated.

[Andrew F. Ali]

Re: LG 47LW6500 LED intermittent

This appears like a typical LG Backlights issue.

[budm]

Re: LG 47LW6500 LED intermittent

Try turning down the backlights as low as possible on ALL inputs to see if the backlights will stay on longer.

[maxvalutech]

Re: LG 47LW6500 LED intermittent

Spot on budm. Have only had one of these LGs before and that had a tuner problem - what a disaster of a menu for settings, the "kiss" model completely overlooked. I don't have a remote with this set so using the touch lights makes for some difficulty but found the picture mode in settings and selected standard for all inputs - this resulted in a much more dimmed picture with backlights at 70℅ but they then stayed on until I turned the set off an hour later. Seems the people who had it were running picture all the way up in brightness etc. It'll be a cheap set for the $10 that I got it for if this simple adjustment works. I do have an LG remote at our main home but forgot to bring it with me (old age!) and we're now 900km away in western NSW.

[maxvalutech]

Re: LG 47LW6500 LED intermittent

Still mucking around with this set but only input I have available in work shed is a DVD via AV. Decided to do a factory reset to see what the settings were then. However started the DVD and let it run for two hours all OK. When I went to get into menu I must have activated input as I saw HDMI 3 on screen just as backlights went off. I also note the temperature has some effect on backlights as in the colder early morning air I could have the screen on for 7/10 mins before it went off - plenty of time for adjustments but this afternoon at 32°C the lights go off almost immediately. Have a remote control coming so that should help make adjustments quicker and easier. Main set in house does have satellite TV with HDMI so will be able to try that input at a setting of 70 for the lights in due course.

[maxvalutech]

Re: LG 47LW6500 LED intermittent

Well I'm back in our main house and able to check this set out properly with dtv signal etc. The led problem was definitely affected by temperature in my opinion and as luck would have it I found in my board stash the same power board which only needed a main fuse replaced. This board has no darkening in the led power output area. Fitted it and set has been running OK for a couple of hours - do have led setting at a low 35 . Now for further testing but I'm hopeful it was a board ic problem rather than LEDs themselves.

[maxvalutech]

Re: LG 47LW6500 LED intermittent

With the set seemingly going OK I turned the backlight setting up to 50 and then noticed a few gray areas around the screen edges. These are shown in pic below. So either some LEDs low in output or not working - don't know the circuit setup for these.

[Andrew F. Ali]

Re: LG 47LW6500 LED intermittent

I think this is an Edge-Lit backlight set up. Since turning down the Backlight setting produces this effect I think you may have some dimly lit LEDs. Only long term solution is to crack open the Panel and replace the LED strip.

[maxvalutech]

Re: LG 47LW6500 LED intermittent

Thanks Andrew F. Getting too old and cantankerous to go far with this set but something a bit strange as well. Turned set on this morning and no sign of side lights problem although top edge definitely dull and moreso top right side. It occurs to me that I hadn't noticed the unevenness before but then I had only ran the set for shortish times and at low backlight settings. When I first noticed the problem the set had been going for around 4/5 hours at 50 setting. Today been going now for 1 hour at 60 setting when attached pic taken. I'm starting to wonder about mura now as well as other reasons.

[maxvalutech]

Re: LG 47LW6500 LED intermittent

Just adding that power board I put in although same eax number did come from a 42" set. For both boards have found with set going OK but with backlights turned up to around 60 when activating menu that causes backlights to immediately turn off ! Why ??

[maxvalutech]

Re: LG 47LW6500 LED intermittent

Very evident now that with lowish LED setting (45 in pic) the display is acceptable and unblemished at switch on, however shortly afterwards the greyish cloud shows across top of screen and slowly extends down about 4/5 inches. The darkening from the sides happens much later. To me as the edge lighting is from the sides it seems a combination of mura effect and some LEDs later dimming possibly due temperature may be at play. Monitoring holes on rear of set though I cannot see any dimming of brightness in them??. Anyone care to comment??

[nomoresonys]

Re: LG 47LW6500 LED intermittent

Seems like if you have same problem with either power board installed, looks like weak or faulty leds, if the voltage going to the leds is correct and steady that is.

[Andrew F. Ali]

Re: LG 47LW6500 LED intermittent

No getting away from it. You have to replace the bad backlights if you really want to get this dolly going again.

[budm]

Re: LG 47LW6500 LED intermittent

no getting away from it. You have to replace the bad backlights if you really want to get this dolly going again.

+1