Emerson ltdn42v68us, 42" LCD, picture goes out, has sound

[noiseguy]

Emerson ltdn42v68us, 42" LCD, picture goes out, has sound. Set's about a year old.

Press on, power light goes from red (standby) to blue (on). Picture and sound come on. After a short time (now about 10 seconds, and getting shorter) the picture flashes a couple times and goes black. Sound stays on, blue light stays on. Indifferent to channels of input (AV, HDMI, etc) and no menu... the screen's just black.

The whole thing reminds me of an old computer with a CPU in thermal runaway... I'm guessing something's getting hot and shutting down.

I'm planning to open it up this weekend to see what's going on. What are the usual suspects here? Any help appreciated.

[budm]

Re: Emerson ltdn42v68us, 42" LCD, picture goes out, has sound

Please take good pictures and use attachment to upload the pictures, then we will see what we can do.

[noiseguy]

Re: Emerson ltdn42v68us, 42" LCD, picture goes out, has sound

OK, I'll tear into it over the weekend and post back with pictures.

[noiseguy]

Re: Emerson ltdn42v68us, 42" LCD, picture goes out, has sound

OK, now for the pics of the boards... only for posterity at this point. The problem is obvious... my 7 y/o daughter pointed it out for me after looking at it for 30 seconds while I was busy checking the other discrete components. The last strand of copper from the far left brown wire broke at my touch.

So... where can I get one of these cables? And how can I keep it from failing like this again? I can't tell, from this, whether it smoked out from high connector resistance, or heat from the nearby transformer (which is immediately below)... seems more likely the former.

[noiseguy]

Re: Emerson ltdn42v68us, 42" LCD, picture goes out, has sound

With the TV busted, I had more time to... fix the TV

Closer pic of the power supply end... this cable is totally smoked. Most brown wires are burned, you can see one red wire has heated at a length from the power supply connection (which looks like it will need to be replaced as well.)

Electrolytic caps are Peace and TLC, mostly.

[noiseguy]

Re: Emerson ltdn42v68us, 42" LCD, picture goes out, has sound

Any help with identifying what these connectors are called so I can run them down and create a new cable would be appreciated... PHR-14 or whatever. Seems like they are a common design between the inverter and power supply, though I note that the ends are different.

If I can't source them, I may just hard-solder the wires to the power supply. Would rather make a new cable... something with slightly higher gauge wires on the TA and TB channels.

[noiseguy]

Re: Emerson ltdn42v68us, 42" LCD, picture goes out, has sound

Heck with the PHR-14 connectors and their crummy little wires. It's a 12 bulb set; I don't know why they run 5 - 24ga wires when they could have just run a single 16ga instead and handled more current... the lines all come together at a single point on the opposite board. As it's set up, it's just an invitation for a cascading failure (one wire fails, which makes the next fail, etc).

So, pulled out the roasted jumpers, cut the leads and soldered doubled-up 18ga wire left over from rewiring my truck. Fixed. One more Wal-Mart X-mas special back up and running.

[drscott]

Re: Emerson ltdn42v68us, 42" LCD, picture goes out, has sound

I had the same problem but red wires and plug burned completly off of inverter board. Hard soldered in three 14 gage wires replacing brown,red and yellow wires. TV works great and no wires getting warm.

[yaketyblah]

Re: Emerson ltdn42v68us, 42" LCD, picture goes out, has sound

I have the same problem, can you tell me what wires got soldered where? There are 5 red 5 yellow and 4 brown respectively but the pins have 5 space 2 space 5. I know how to solder but don't understand the circuitry. Thanks

[madchemist24]

Re: Emerson ltdn42v68us, 42" LCD, picture goes out, has sound

I found this site and specifically, this thread while looking up info on our tv.
In my searching, it seems this model was only available at Wal-Mart and was sold on Black Friday 2010. Also, it appeared that between 90 days and 15 months of use it was prone to the screen going black with audio working only.
Like the others listed on multiple sites, we got our as a Black Friday special in 2010. We got the tv to be used as a video monitor for my son's xbox. Up until a few days ago, it ran flawlessly about 4 hours a day.

While running some Black Ops, it started sparking from the upper right corner, then the screen went out.
All my searches were showing similar problems, but none covered the cause until I found this thread.
The photographs posted above may as well be from my tv. The very same wires were affected. All four brown wires and one yellow were toasted. The connectors were melted and the wires were brittle about 4 inches up the harness.

I am contemplating soldering new leads directly to the board, but what concerns me is what actually caused the sparking. I am not so sure I agree with the OP about the transformer. It does not have any marks on it to indicate it got hot enough to melt the connectors or the insulators on the wire ends. There is, however, evidence of arching and burning. It is possible that the wires are under-sized and a heavier gauge will be the correct solution. But I cannot be sure.

So, my question is this: Did we all buy a fire hazard and are we asking for trouble by rewiring them and placing them back in service.

[rpridenh]

Re: Emerson ltdn42v68us, 42" LCD, picture goes out, has sound

I just picked up one of the sets from the recycling center in my town. I bet when I open it up I'll find the same exact failure. Wonder how many of these have been tossed from the two Wal-Marts in my area. This just kind of confirms my wife's theory that Wal-Mart tends to sale off sub-standard electronics.

[noiseguy]

Re: Emerson ltdn42v68us, 42" LCD, picture goes out, has sound

I guess I shouldn't be surprised at the number of failures on this I'm seeing. I bet there's a bunch of these ending up in landfills.

BTW, failure mode was smoke, smell, and some sparking. It was the wires frying up. Frankly, this repair is less likely to catch fire than the OEM design.

rpridenh: If you post up pics of the back of the main board and PM me, I'll show you where I soldered things up.

One thing that's a bit troubling is that yellow wires are used with red, other yellow, and brown wires. It's like they ran out of 24 ga in the right color at the plant. So you need to pay attention to where the wires are headed, rather than their colors.

[baileyb]

Re: Emerson ltdn42v68us, 42" LCD, picture goes out, has sound

I guess I shouldn't be surprised at the number of failures on this I'm seeing. I bet there's a bunch of these ending up in landfills.

BTW, failure mode was smoke, smell, and some sparking. It was the wires frying up. Frankly, this repair is less likely to catch fire than the OEM design.

rpridenh: If you post up pics of the back of the main board and PM me, I'll show you where I soldered things up.

One thing that's a bit troubling is that yellow wires are used with red, other yellow, and brown wires. It's like they ran out of 24 ga in the right color at the plant. So you need to pay attention to where the wires are headed, rather than their colors.

Same model, same 2010 Black Friday special, same wires burned...
I am trying to determine if I can repair this myself. I ordered a new inverter board and power supply, but cannot locate the 14-pin connector. If I can solder new wiring, and keep my TV, I would be thrilled.

But, I do need some instruction. Could you post the picture of where you soldered things? That would be incredibly helpful. I am attaching pictures of my boards and the wiring. Thanks so much!!

[tom66]

Re: Emerson ltdn42v68us, 42" LCD, picture goes out, has sound

You can just leave the end on the inverter connected, and cut the broken connector off. Solder some thick gauge wire connecting all the "TA" wires to one point, all the "TB" to the one point and all the GND to GND.

[Jim1590]

Re: Emerson ltdn42v68us, 42" LCD, picture goes out, has sound

Don't do anything yet. Depending on the answer to the question in my thread about the same model, mine may be parted out. I can throw this cable set in the mail for you. It is different colors (all white like set going to the main board) but it is the same wire. I think.... lol



nope, its done.

shoot me an address via pm and I can drop it in the mail if you would like

[Rasello]

Re: Emerson ltdn42v68us, 42" LCD, picture goes out, has sound

Hello everyone, I've been running across the exact same problem as everyone else here. TV was working fine one day ( I have an Emerson LTDN42V68US) and then the monitor went out. Audio was still good, power was still running and my circuit board was fried exactly the same way as everyone else's on here. I had a question specifically to Tom66 and Noiseguy. If either of you had some other photos showing exactly how you soldered the wires to the board and what cables they were connected to that'd be great.

I have little experience in Printed Circuit Boards and so was confused when Noiseguy had what looks like 4 Blue wires and one white wire attached to the lower board. I'm under the impression that since there's only three categories of of Acronyms with pins IE "TA" "GND" and "TB" that i'd only need three low gauge wires to solve the problem.
I'm also assuming that if I connected the thin and thick wires together I could leave the plastic pin housing on and attach the wire to all the pins in a row?
For example I have all the pins touching the thicker wire kind of like stops on a bus route?

Any and all help is GREATLY appreciated. I'm trying to get my friend's TV working because there's an AWESOME Borderlands sale on Xbox right now and the add-ons are 50% off.

Please excuse me if I have any improper thread etiquette. I don't mean to come off as asky begging or demanding. Thank you all again and I hope to hear from you soon.

[Rasello]

Re: Emerson ltdn42v68us, 42" LCD, picture goes out, has sound

You can just leave the end on the inverter connected, and cut the broken connector off. Solder some thick gauge wire connecting all the "TA" wires to one point, all the "TB" to the one point and all the GND to GND.

Heck with the PHR-14 connectors and their crummy little wires. It's a 12 bulb set; I don't know why they run 5 - 24ga wires when they could have just run a single 16ga instead and handled more current... the lines all come together at a single point on the opposite board. As it's set up, it's just an invitation for a cascading failure (one wire fails, which makes the next fail, etc).

So, pulled out the roasted jumpers, cut the leads and soldered doubled-up 18ga wire left over from rewiring my truck. Fixed. One more Wal-Mart X-mas special back up and running.
Attached Thumbnails

^^The two posts I understand but not completely^^

[tom66]

Re: Emerson ltdn42v68us, 42" LCD, picture goes out, has sound

Basically, take all the pins all the RED connect, and all the pins the YELLOW connect, and replace with one 16 gauge or so wire. Leave the other thin wires (if any) still connected.

[Rasello]

Re: Emerson ltdn42v68us, 42" LCD, picture goes out, has sound

Hmm, I appreciate your help but I think I may still be confused. If you could tell me where there's an error in my logic I can probably sort the rest out.

At the end of connecting all of these smaller wires to thicker 16 Gauge wire I should have three wires ending up attached to the white board right?

Also those wires don't have to be attached to all the TB GND and TA pins, just one will do?


Or is there a specific place on the board where I solder it instead? Thank you for your patience. I can post pictures if you need them.

[Rasello]

Re: Emerson ltdn42v68us, 42" LCD, picture goes out, has sound

*update*

So I went out on a limb and tried it.
Great news! It's working like a charm! I took the three groupings of wire 5,2,5 and connected them all to one coil of 14g wire each. I took the two spare cords and covered them in shrink wrap and then soldered the tips of the three 14g wires to a few contact points UNDER the board. I decided to leave the plastic housing on up top in case it didn't work and my soldering was a bit messy.