LG 42LV5500 TV, Backlights on, No picture

[henryvrensburg]

Good day guys

I picked this TV up from a friend.

When you switch the TV on, the backlights switch on, and stays on. However there is no picture. Sometimes a small band on the top of the TV can be observed, about 1cm thick, and when the Home button is pressed, you can see the band changing, suggesting a change in the item displayed.

My first thought were T-CON. I removed one of the bands going to the panel, and half of the screen lights up slightly, same result with other band removed. The voltage going to the T-CON however is only 10.02V. The T-CON fuse is functional. Voltages on both sides are 10.02V. Voltage at Mainboard LVDS connector is 10.02V (Ground probe on chassis)

I could confirm the voltages as per P201 exactly as in the legend on the PSU. 12V on PSU going to Mainboard reads 12.01V

Can someone please confirm my suspicion of a bad Mainboard, or can you suggest further tests I can do.

Thanking you in advance

[neilc6]

Re: LG 42LV5500 TV, Backlights on, No picture

LV and LS series suffer from bga failures on the mainboard. Lots of repair services on ebay if you search.

[henryvrensburg]

Re: LG 42LV5500 TV, Backlights on, No picture

Thank you Neilc6. Will try that.

[yokoono]

Re: LG 42LV5500 TV, Backlights on, No picture

It is very possible that the US1 integrated on the t-con may be defective.

[henryvrensburg]

Re: LG 42LV5500 TV, Backlights on, No picture

Hi guys

With reference to above posts, I unhook the LVDS cable from the T-CON. The Voltage reading on the Mainboard side of the LVDS cable is 11.63V.
Does this still suggest a bad Mainboard(these boards are very expensive)or can it be a faulty T-CON. The reading on the T_CON fuse is 10,02V.

Is 11.63V good enough to power the T-CON

[nomoresonys]

Re: LG 42LV5500 TV, Backlights on, No picture

Seems like if it's coming out of mainboard at 11.63 which is ok and ending up 10.02 at tcon, makes me think it's a tcon issue, maybe try unhook tcon from panel and see if it's still 10.02.

[henryvrensburg]

Re: LG 42LV5500 TV, Backlights on, No picture

Hi nomoresonys

I took voltages on the T-CON fuse with LVDS removed from panel. Still reads 10.02V. I'm going to replace the T-CON and see what happens.

Thank you for the help

[nomoresonys]

Re: LG 42LV5500 TV, Backlights on, No picture

Ok, hope it works.

[Moreno83]

Re: LG 42LV5500 TV, Backlights on, No picture

https://3.bp.blogspot.com/-Ex-aKMD06...2lv4500-03.jpg


check the cold solder joint. Problem on all these sets...

[henryvrensburg]

Re: LG 42LV5500 TV, Backlights on, No picture

Hi guys

As per previous posts, I replaced the T-CON but with no change. The backlights does come on, and stays on, but no display. Am I looking at a bad Mainboard?

[vinceroger69]

Re: LG 42LV5500 TV, Backlights on, No picture

maybe another faulty t con board on the top of the tcon you have two ribbon cables if you disconnect on side and turn tv on whats shown on the screen? try the same thing on the other top ribbon cable