Electronics > Repair

LCD TV repair

(1/3) > >>

HinesNetwork:
I'm hoping someone can point me in the right direction for repairing my Sony LCD TV. The TV has horizontal lines on it for all of the inputs, however if the coax (antenna) input is using the over the air inputs it doesn't have the lines. If for example I hook up a direct tv box using coax to the input I get the lines again. But, if I connect the direct tv box to the TV by just connecting the center pin of the coax (although the image isn't complete) the lines on the LCD go away. This leads me to believe the issues has something to do with the external components being coupled to ground. Does anyone have any ideas what I might check on the tv to figure out why this is happening?

Side note: I just got my digital oscilloscope and can test things, I'm just not sure where to start.

Thanks for an help you can give.

Jason

Psi:
Yeah, it does sound like a grounding issue is involved.

If it was me, the first thing i'd do is try a coax TV signal isolator and see if it fixes the problem. If it does i'd probably just leave it on and forget about the problem.

But if you want to fix it then i'd probably look at the components around the RF input section. It's possible that a capacitor in there has become shorted and something is getting earthed that shouldnt be.

(Side thought. I have seen lines on a TV when someone had a powerful RF distribution amps feeding their TV directly and the signal was way to powerful for the TV to handle.)

zaoka:
Can you post a picture?

HinesNetwork:
I guess I should have said this in my first post, oops, but the issue is really that I'm getting lines on all the inputs (HDMI, AV, etc.). I don't usually use the coax input, I just found while troubleshooting that the coax input doesn't have the problem if it has an antenna or nothing hooked up to it. But as soon as I hookup my direct tv box via the coax the lines show up. My goal is really to repair it so the lines don't show up on the HDMI inputs.

Here's an image of the coax input, without anything connected, with a menu up: http://note.io/13uVj25

This is an image of the HDMI input: http://note.io/Sytftm

Thanks,

Jason

tom66:
I would advise re-seating the LVDS cable. This is the cable which runs from the main board (AV inputs) to the T-con board (usually under a shield, connects to the LCD panel.)

Navigation

[0] Message Index

[#] Next page