JVC LT-37X688 Stange Vertical Lines Problem

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  • mcnaryxc
    Member
    • Nov 2009
    • 13

    #1

    JVC LT-37X688 Stange Vertical Lines Problem

    So, I get this JVC LT-37X688 for free on CL. The guy gives it to me and says the TV turns on, backlight comes on, but no picture. I get the TV home and when I turn it on, sure enough, that's what happens.

    I open the TV up to see any problems. This is one of those JVC with the pointless bobby-trap photosensor, so I covered it up with electrical tape. No bulged caps, nothing visibly burned. But then I look closer and the LVDS cable was unplugged. I'm thinking "Sweet! Easy fix!" so I plug the cable in and fire the TV on. The picture came on, but had these crazy vertical lines across the screen every time I turned the TV on. (See first picture.) The first thing that comes to mind is that it must be a panel tab problem, which erased all my happiness.

    I further take apart the TV down to the tabs. I pushed down on and wiggled all the tabs and the only one that really seems to make the TV show a notable change is the top right. The thing is that tab (or any of them) didn't get rid of the full screen of lines at all. With that, I couldn't quite figure out the right way to hold the tab to get the signal working, so I just did a "bumpers fix" that I've done on other Sony and Toshiba TVs, which squeezes that little IC in the ribbon cable on the tab with rolled up electrical tape. And this is where I get really confused on fixing the TV.

    I turned it on and the JVC splash screen pops up (See Picture 2), followed by the TV channel. It works! It never did that when I got lines. I have no idea how that happened, so the suspicious person that I am, I decide to put a little of the TV back together, and let it cool down. After it cooled for a while, I turned it back on and sure enough, the lines came back. Ugh. But then, I turned it off, then right back on, and the splash screen came back and the TV worked. lol I don't get it!

    But that's not all! One other weirdness that I discovered has to do with the HDMI inputs. With this TV, there's two "main" boards: analog and digital. The analog has the composite, s-video, component ports. Digital has HDMI, coax cable and toslink optical ports. Analog plugs into digital, digital plugs into T-con. When I'm on the TV channel input (cold start), I get lines. When I switch to HDMI inputs, I get NO lines but rather a no signal message (See Picture 3). When I then switch to other analog inputs, I get lines again. When I get the splash screen on start up, all the inputs show up normal. Confused yet?

    More notes: I tried to use the HDMI ports, but I can't get a signal to go through, which makes me think someone opened the TV up before and the photosensor screwed up the HDMI. I don't have the remote control to fix it, so it'll have to wait. The person I'm giving the TV to won't use the HDMI ports anyway, so it's a low priority.

    I can't seem to pinpoint the problem. Any advice?
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  • tom66
    EVs Rule
    • Apr 2011
    • 32560
    • UK

    #2
    Re: JVC LT-37X688 Stange Vertical Lines Problem

    I would doubt it is a tab bond issue; even if you had not said anything about the analog/digital boards, the symptoms do not fit.

    There is probably a processor on the analog board which converts all the analog inputs to a single digital input, and this may be going bad.

    How about pictures of each of the major boards?
    Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
    For service manual, schematic, boardview (board view), datasheet, cad - use our search.

    Comment

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