LG 42LV5400-UB Touch panel buttons not working

[TubeJunkie]

Hello. I have a LG TV model 42LV5400-UB. The touch buttons on the front panel does not work. Didn't get the factory remote with it either. The picture and sound work great. But I can't change inputs, volume, channels, power button, or access the menu. When AC power cord is plugged into AC outlet, the TV starts up. And is on HDMI 1.

I'm pretty handy with soldering and I've downloaded the service manual, if only someone could point me in the right direction. I can take some voltage readings. Any help will be greatly appreciated. If I fix it, I'll donate to BadCaps.net. Thanks

[freakaftr8]

Re: LG 42LV5400-UB Touch panel buttons not working

Sometimes these touch button s can get "touchy". Have a look first at the connector that goes to the button control pad from the mainboard.

Make sure the button control is receiving 3.5v to 5v. Also make sure that nothing like liquid has been spilled there. People like to wash screens with Windex. A big killer of electronics and circuit boards.

[mmartell]

Re: LG 42LV5400-UB Touch panel buttons not working

If you've already opened it then you will have verified if the board has peeled itself off it's mount or not. The glue is very tacky but who knows... the buttons won't work if they're not mated to the plastic bezel.

[TubeJunkie]

Re: LG 42LV5400-UB Touch panel buttons not working

The button board doesn't look like anything has been spilled on it, but you can't tell if Windex has been used on it. And that board is firmly attached. I tried prying it out, but it didn't budge at all. I took some voltage readings from the input/output board that the button board is connected to. Pic included. I get 3.4 vdc on all pins except the following colored wires .From top of pic. No voltage on: Black, blue, white, gray, purple, & green.

I also got the same readings at the cable end that connects onto the button board.

[freakaftr8]

Re: LG 42LV5400-UB Touch panel buttons not working

What you can do is probe any colored wire while you press on the buttons. If you are a feedback voltage (which I believe this is how it works) it may be a mainboard issue.
Any LG or vizio remote will turn the set on and off. Wondering if IR works.

[vinceroger69]

Re: LG 42LV5400-UB Touch panel buttons not working

could this set possibly of come from a hotel etc as maybe in hotel mode if thats the case sometimes the touch buttons etc are disabled
https://www.youtube.com/watch?v=lNW_0D7cykw this video at about 42 seconds in shows what can be disabled

[TubeJunkie]

Re: LG 42LV5400-UB Touch panel buttons not working

Hey guys, Thanks for chiming in. I got a Vizio remote, and it does nothing. I tried probing the colored wires with my meter, while hold the power button on the front panel. Nothing there either. I unplugged the connector from the button board while it was powered up, and plugged it back in, and now its stuck on component 1 input, instead of HDMI 1. Now I cant really use it. Dang it. Just my luck. lol... I'm most certain the IR doesn't work. Since the Vizio remote done nothing. Any more ideas fella's? Thanks Again

[vinceroger69]

Re: LG 42LV5400-UB Touch panel buttons not working

if you have a android device you could try this lg remote app here are what you need, it is very easy, just audio or IR with android

[R_J]

Re: LG 42LV5400-UB Touch panel buttons not working

The vizio remote won't work, you would need an LG remote (different remote codes) turn off the tv, connect the source hdmi device, then power on the tv then the source device and see if the tv finds it.

[TubeJunkie]

Re: LG 42LV5400-UB Touch panel buttons not working

I downloaded the LG Remote app to my Motorola Xoom tablet. The app can’t find the tv. I tried to rescan, but to no avail. My son has an LG tv Remote, that I’ll borrow ASAP. Any other ideas ? Thanks

[TubeJunkie]

Re: LG 42LV5400-UB Touch panel buttons not working

Should there be 3.4 volts on all pins that connect to the button board? There are six pins with no voltage, as I previously stated. I've tried looking at the service manual, but I can't tell if all pins should voltage. I know there's two ground pins that shouldn't have voltage. But, I'm just stumped right now. Someone please guide me in the right direction. Thanks

[freakaftr8]

Re: LG 42LV5400-UB Touch panel buttons not working

The 6 pins should be outputs and such. What happened with the LG remote? Any luck?

3.4v is about right.

[TubeJunkie]

Re: LG 42LV5400-UB Touch panel buttons not working

That’s what I was thinking about the pins with zero voltage. My son can’t find his LG Remote. I’ll have to buy one, I guess. But I seriously doubt any Remote will work. I got this tv from a recycle center. When I opened it up, I noticed someone had cut the speaker wires. Probably because they couldn’t control the volume. I repaired the speaker wires. I’ll definitely try an LG Remote when I get one. I’ve read this is a known problem with this model / series of LG tv’s. I’m not a fan of the Soft Touch button deal! Now, more than ever! Lol