42LD75LGD: No sound and no input/output. Main board fried?
I have an LG 42LD75LGD TV that has recently stopped playing sound and the input/output no longer work (both video and audio). I couldn’t test everything for lack of cables/peripherals. My findings:
The only thing that seems to work is the image from the cable. The sound doesn’t come through.
the three hdmi ports do not get the picture across to the screen. However, in the input menu, I can see the TV detects which port has a source connected. When I select the connected hdmi port, I can hear a faint buzzing/whistling, but no image comes.
When using the VGA cable, I get some “snow” on the screen.
I have no sound and I cannot get the sound (of the TV programs) out through e.g. the headphone jack.
So my questions are the following:
- is it 100% sure that it is the main board that is the cause, or can this be related to something else too?
- I doubt they still make the main boards, so can it be fixed (I’ve read things about baking the main board in the oven)?
- Otherwise, is it possible to just use some other board? I actually really don’t care about any of the smart features. I just want to use this TV as a screen (input from HDMI).
Thanks in advance!
Hi oldturkey03, and thank you very much for your detailed answer!
The latest part (universal LCD driver board) actually got me really interested, so for the time being I’ll forget about fixing the main board. As I wrote, I’m planning on using that TV set as a monitor only (streaming through chromecast, computer, etc.). So if I can get rid of all the so-called smart functions that take forever to load and that I don’t need, all the better!
I will pop open the TV and look for the LCD panel and power board numbers. And then I’ll try to see where the T-con board is to get its ID too and get back to you.
Update 2 (10/07/2019)
I have re-opened the back panel of the TV, and since I am not sure where to look for the LCD panel number, I took a picture of the whole thing. I don’t suppose the panel number is one of those circled, or could it? I suppose I’ll have to detach the panel from that back metal plate in order to access the panel number…
Since it was quite late I decided to postpone this next stage, but while removing the main board, something drew my attention. One of the heat sinks does not seem to be in contact with the surface of the component it’s supposed to help cool down. Or at least I’ve never seen heat sinks placed like that, but then again, I have really no notion of electronics, so that’s why it’d be nice if someone could confirm (or infirm) this.
And just in case the conversion from TV to monitor is unsuccessful, should I try to re-attach this heatsink to its component before I bake the board in the oven as a last attempt at fixing the TV? If so, how should I go about doing it?
Update 3 (10/07/2019)
Don’t worry, it’s not your eyes, it was the picture :-D. I had taken it to have an overview of the whole thing, the idea wasn’t to be able to read those small prints on the labels. But anyway, here are close-ups of those two labels in the center, hopefully one of those is what we’re looking for! I would bet the one that reads LG Display?
And out of curiosity, I lifted the heat sink, and it was barely touching the component underneath. When I looked at the thermal glue (or double-sided tape or whatever it is), it seemed like it has been attached to the component only from the edge from the very beginning. There’s only a line imprinted in the glue that corresponds to the place where it was in contact with the component. The component itself did not present any apparent damage, but also no trace whatsoever of any thermal glue on it. See the pictures below:
And I was going to forget the main board number. Here are two pictures, one with all labels on the upper side, and if that doesn’t suffice, there was a number engraved in a piece of metal on the back, if that’s of any help.
So now, how do I match my display (provided one of those labels did have the display number) to an LCD driver board? And how do I get my hands on one? :-)
And oldturkey03, I cannot overstate how precious your help is! Thank you very, very much!