Emerson LC401EM3F Backlight and Audio Work, No Video

[arod]

Hello all! I have just started picking up broken televisions and trying to repair them as a hobby. I picked up a 40" Emerson LC401EM3F on Craigslist and have started troubleshooting it, but I am not sure what my next steps should be.

I was having power supply issues when I first started looking at it. The television would power on for about 2 seconds (with backlight) and then go immediately back to standby mode. For some strange reason, yesterday this problem disappeared and I was able to get the backlight to stay lit. Additionally, I plugged in a source into the HDMI port and the sound was working! However, there is still no video available. When I first picked up the television, I purchased a used but functional digital main board (TCON - A17PHUH). I attempted to swap out the digital main board and there was no effect on the video. The same problem exists (backlight on - sound works, but no video).

I have the service manual and have been looking through it, but I am lost as to how to troubleshoot at this point. Are there specific points on the TCON board that I can check to ensure it is getting power?

The service manual can be found at this link .

Thanks in advance.

[capkid]

Re: Emerson LC401EM3F Backlight and Audio Work, No Video

The link you posted brought up a Philips LCD TV's service manual. If the Emerson is identical, check the fuse on the t-con for continuity. If the fuse is bad, you can either replace it or solder another one on top of the old fuse (the latter is easier).

Edit: I had the same issue a couple years ago with the Philips 40PFL3705D/F7 TV. You can very temporarily install a jumper wire between both ends of the fuse for grins to check the picture. Here's the fuse I installed: http://www.digikey.com/product-detai...5TR-ND/1206513

[arod]

Re: Emerson LC401EM3F Backlight and Audio Work, No Video

The link you posted brought up a Philips LCD TV's service manual. If the Emerson is identical, check the fuse on the t-con for continuity. If the fuse is bad, you can either replace it or solder another one on top of the old fuse (the latter is easier).

Edit: I had the same issue a couple years ago with the Philips 40PFL3705D/F7 TV. Here's the fuse I installed: http://www.digikey.com/product-detai...5TR-ND/1206513

As far as I can tell, the two televisions are identical and the parts interchangeable. I apologize in advance, but I cannot find any fuses on the TCON board. I even searched the schematics and did not find reference to them on the digital main board. See attached photo. I was expecting to see something near the two black connectors that are inputs to the board.

[capkid]

Re: Emerson LC401EM3F Backlight and Audio Work, No Video

The picture you posted is a bit fuzzy. I would expect the fuse to be near the LVDS connector on the right-hand side of your pic, but it's cut off in your picture.

[selldoor]

Re: Emerson LC401EM3F Backlight and Audio Work, No Video

If you cant find a fuse or strategically placed 0 rated resistor start by testing the voltage
accross the capacitors

[arod]

Re: Emerson LC401EM3F Backlight and Audio Work, No Video

I verified 12VDC on the pins (1-4) that go from the digital main to the LCD module. I presume the fuse you are referring to would be inline with this input. However, I may be looking in the wrong place.

I have never heard of a 0 ohm resistor. Is this a resistor that has essentially no resistance?

The schematic for the digital main can be seen on pages 53-58 of the referenced PDF in my first post. A top-level overview of inputs and outputs can be viewed on page 66-68. Any additional guidance is appreciated.

Thanks

[budm]

Re: Emerson LC401EM3F Backlight and Audio Work, No Video

Can we see the whole back side of the TV?
That is the main board, not T-CON board.
http://www.shopjimmy.com/emerson-a17...l-main-cba.htm
Is the LCD panel this number? LTA400HM09-F05
T-CON board is under the metal shield top center of the screen, you need to find out if you do have 12V at the SMD fuse on the T-CON board.

[arod]

Re: Emerson LC401EM3F Backlight and Audio Work, No Video

Can we see the whole back side of the TV?
That is the main board, not T-CON board.
http://www.shopjimmy.com/emerson-a17...l-main-cba.htm
Is the LCD panel this number? LTA400HM09-F05
T-CON board is under the metal shield top center of the screen, you need to find out if you do have 12V at the SMD fuse on the T-CON board.

Sure, see attached photos. The LCD panel is LTA400HM09-F05. I figured that was the LCD display driver board. I will check accordingly. Thanks.

Edit: Found the fuse and it appears to be blown. I will try jumping a wire temporarily and see what the results are.

[budm]

Re: Emerson LC401EM3F Backlight and Audio Work, No Video

Ooo, it is one of those LCD panel with integrated T-CON.
You will have to take the panel apart to get to that long PCB where the LVDS connector is attached to to see where the SMD fuse is.

[arod]

Re: Emerson LC401EM3F Backlight and Audio Work, No Video

Well... After jumping the wire, I believe there was a picture. Unfortunately, I was not in a position to see it when I powered the unit on since I smelled burning and saw a puff of smoke and quickly disconnected the power. There is a reason fuses are integrated in the board...

[budm]

Re: Emerson LC401EM3F Backlight and Audio Work, No Video

I think you are out of luck on this cheaply made screen not to be repaired.

[aaronwt6]

Re: Emerson LC401EM3F Backlight and Audio Work, No Video

I'll give you one small piece of good news arod. The power supply you have there is worth around $70-$90 on Ebay. I've sold several recently. Just a heads up before you pitch anything.

[ImHereForThePics]

Re: Emerson LC401EM3F Backlight and Audio Work, No Video

I have the same model tv with a similar problem. It has a blue screen and audio but no picture. What could be the problem?

[ImHereForThePics]

Re: Emerson LC401EM3F Backlight and Audio Work, No Video

Anybody got any thoughts on this subject?

[CapLeaker]

Re: Emerson LC401EM3F Backlight and Audio Work, No Video

Check the LVDS with an oscilloscope and turn on and off the Menu all the time.