Hisense (emerson) LTDN-42v68US no picture, yes sound

[Jim1590]

Just got this TV from a guy for $30, known issue. Hisense (emerson) LTDN-42v68US

This thing looks mint. Man date of 8/11 and it still has the clear sticky around its edges and the promo stickers in upper corner. The new TV on the guys wall has the same still on.

TV power on, 3 red blink, screen lights up black.

Hook up my old xbox to it and get volume (can control and mute with remote) with same blink code. No picture, screen lights up black.

So power board should be working, backlight board is working, IR board is working, can change inputs, adjust volume and mute so main board might be working

I can press my finger on the display and get that wavy lcd reaction so panel seems intact. You know, the thing we yell at our kids for doing.

Similar issues to this thread: https://www.badcaps.net/forum/showthread.php?t=20599

Thinking main board, LVDS wire itself (no obvious wire problems such as fraying broken connections) or does this thing even have a control board? Do not see any bulging caps on the main board, I can do simple tests with my multimeter, or should I just get a new board. I would love for this to be a bad cap or two because those are the cheapest fixes!

Main board is RSAG7.820.2278/ROH Rev B
Inverter Board is " " " ".2124 " "
Power Board is " " " ".2123 " "


Thanks all!

[Jim1590]

Re: Hisense (emerson) LTDN-42v68US no picture, yes sound

Apologies, here are pictures. Power board is 2 pics to give better view.

[Jim1590]

Re: Hisense (emerson) LTDN-42v68US no picture, yes sound

Higher res and zoomable I think

[johnboy1313]

Re: Hisense (emerson) LTDN-42v68US no picture, yes sound

Should have 12V (I think) on some of the wires on the LVDS. This set apparently doesn't have a typical T-con. Whatever the other end of the LVDS connects to may have a fuse on it. If it does, check if it's blown.

[Jim1590]

Re: Hisense (emerson) LTDN-42v68US no picture, yes sound

I took a look at it and I would have to fully disassemble the lcd protective framing and bezel to get close to it.

I have attached a pic, the space for the board is a half inch high at most.

Willing to do it, but not sure if I want to dive that much into it yet. I have taken lcds fully out before on 15" monitors to make lcd projectors, but this would be a tad bigger.

[ben7]

Re: Hisense (emerson) LTDN-42v68US no picture, yes sound

Whatever the other end of the LVDS connects to may have a fuse on it. If it does, check if it's blown.

Good idea! It seems some sets are known to blow fuses even when there is no short.

[Jim1590]

Re: Hisense (emerson) LTDN-42v68US no picture, yes sound

Success, had to remove a lot of sticky foam from the bezel and was just able to get the screw driver in. Here is the board running left to right. It goes the width of the TV on the top. Some overlap should be there so you can get an idea of whats where.

I looked at both ends of circuit boards but nothing is labeled 12v, should I just start sticking my multimeter in, grounding on frame and see what values are?

[ben7]

Re: Hisense (emerson) LTDN-42v68US no picture, yes sound

Success, had to remove a lot of sticky foam from the bezel and was just able to get the screw driver in. Here is the board running left to right. It goes the width of the TV on the top. Some overlap should be there so you can get an idea of whats where.

I looked at both ends of circuit boards but nothing is labeled 12v, should I just start sticking my multimeter in, grounding on frame and see what values are?

In your 4th picture, test the resistance of FP1

[Jim1590]

Re: Hisense (emerson) LTDN-42v68US no picture, yes sound

ok, I am sure I am probably doing it wrong, never tested one of those before.

multimeter set to diode under ohms placed with black at top of FP1 and climbed up to 1.710 before took it off, reversed leads and got .000

set to ohms 200 and got no reading.

this was with power to set off.

thanks

[ben7]

Re: Hisense (emerson) LTDN-42v68US no picture, yes sound

ok, I am sure I am probably doing it wrong, never tested one of those before.

multimeter set to diode under ohms placed with black at top of FP1 and climbed up to 1.710 before took it off, reversed leads and got .000

set to ohms 200 and got no reading.

this was with power to set off.

thanks

No resistance across that fuse? Sounds like it is bad.

Try probing the resistance from each end of the fuse to ground. What do you get?

[Jim1590]

Re: Hisense (emerson) LTDN-42v68US no picture, yes sound

On ohm 200 black on wall mount bracket metal red on top part of FP1 no power to tv get 00.4, red on bottom of FP1 1.blank

top and bottom are obviously the same as in the picture

I will assume that I picked a good source of ground. please educate me if my assumption is faulty!

thanks

[ben7]

Re: Hisense (emerson) LTDN-42v68US no picture, yes sound

On ohm 200 black on wall mount bracket metal red on top part of FP1 no power to tv get 00.4, red on bottom of FP1 1.blank

top and bottom are obviously the same as in the picture

I will assume that I picked a good source of ground. please educate me if my assumption is faulty!

thanks

I think your source of ground is good.

00.4 is just about half an ohm - short circuit!

You will be needing a new t-con. Too bad it is soldered to the panel!

I'm not sure, it might be that there is a voltage regulator that is bad, which would be good - easily fixable. Otherwise, that big chip could be bad, and it takes special equipment to replace that...

[truep]

Re: Hisense (emerson) LTDN-42v68US no picture, yes sound

Before you give up, solder a wire to the first left hand pin of the connector, re-assemble and check the voltage. It should be either 5 or 12V black on the frame.. I had an LVDS cable failure I found that way.

[Jim1590]

Re: Hisense (emerson) LTDN-42v68US no picture, yes sound

I actually did find a tcon board in china for 66 shipped. just have to see if the brown flexible cables are clipped into the display or not.

truep, can you elaborate some? the pin lineup at either end is different. Here is a picture of the cable: http://www.ebay.com/itm/Emerson-Hise...item20d4431bb5

Seems the cable is a problem child with this tv after some searching around. Should I order the cable, hope for the best? Or is the tcon without a doubt shot?

Thanks

[ben7]

Re: Hisense (emerson) LTDN-42v68US no picture, yes sound

I actually did find a tcon board in china for 66 shipped. just have to see if the brown flexible cables are clipped into the display or not.

truep, can you elaborate some? the pin lineup at either end is different. Here is a picture of the cable: http://www.ebay.com/itm/Emerson-Hise...item20d4431bb5

Seems the cable is a problem child with this tv after some searching around. Should I order the cable, hope for the best? Or is the tcon without a doubt shot?

Thanks

By the looks of your pictures, the flat cables going to the display are soldered to the t-con board! What a cheap POS. It only costs an extra dollar to add connectors in there ... but the designers now-a-days don't care careabout fixability one bit!

I think the tcon is shot. The fuse is blown open circuit.

[Jim1590]

Re: Hisense (emerson) LTDN-42v68US no picture, yes sound

yeah I am afraid of that. I will find the link to that tcon when I get home and post it up. Maybe something is workable.

But I also only got into this for $30 so it is not like I am attached to it. I can always pull parts and sell cheap as-is on ebay. Done it before to recoup $ and not make profit since I can't fully say yes it works.

[Jim1590]

Re: Hisense (emerson) LTDN-42v68US no picture, yes sound

Can I do anything to further diagnose and replace a component of the board? I do not have anything beyond a small soldering iron and a multimeter, but can spend a little to get what I need such as a small tip iron or something.

[Jim1590]

Re: Hisense (emerson) LTDN-42v68US no picture, yes sound

Here is the one I found:
http://www.aliexpress.com/item/Konka...812570697.html

[ben7]

Re: Hisense (emerson) LTDN-42v68US no picture, yes sound

Here is the one I found:
http://www.aliexpress.com/item/Konka...812570697.html

Looks good to me, but, are there connectors on the panel? Why does it come with the little flat cables? That is the only reason I can think of.

[Jim1590]

Re: Hisense (emerson) LTDN-42v68US no picture, yes sound

Yeah, don't think that is doable at my knowledge level.

On the other hand, I tested the FP1 with power ON screen lit up. With ohms set to 200, black on frame red at top of FP1 got 3.3.

I also volt checked the LVDS cable and the far right cable going into this screwed up tcon reads 11.89v with volts set to 20, black on frame and red on pin.

So maybe some hope?