Westinghouse EW50T5KW - Backlight but no image

[AFajitas]

When I turn it on, the backlight fires but I get no image. I tried to fix this TV last year by shotgunning parts at it when I didn't know any better. I replaced everything, in this order: Mainboard, TCON, PSU. When I replaced the PSU I had noticed that the old PSU was letting off a faint squealing sound. Wondering if I fried the new mainboard. How can I test it? I am getting all the proper voltages on the power supply header that goes to the mainboard.

Pics attached.

[AFajitas]

Re: Westinghouse EW50T5KW - Backlight but no image

Bump. Need some guidance on how to isolate this issue.

[selldoor]

Re: Westinghouse EW50T5KW - Backlight but no image

There is a small fuse on the Tcon at F102 what is the voltage on each side with respect
to ground. Also how many ohms across it.
As this is F102 can you find F101????

[CapLeaker]

Re: Westinghouse EW50T5KW - Backlight but no image

First make sure the power supply works. I think you know how to force jumper it on.
If the main board fires up, you should be able to detect some LVDS activity on the oscilloscope. Just press the menu button all the time, so that the screen would have to display it. Turn the menu on and off, there should be a change in the LVDS signal. The LVDS signal is quite low btw. Also make sure the T-con is getting power from the main board.

[selldoor]

Re: Westinghouse EW50T5KW - Backlight but no image

First make sure the power supply works. .

POST1 " I am getting all the proper voltages on the power supply header that goes to the mainboard"

[CapLeaker]

Re: Westinghouse EW50T5KW - Backlight but no image

POST1 " I am getting all the proper voltages on the power supply header that goes to the mainboard"

Help! My brain is leaking!

[AFajitas]

Re: Westinghouse EW50T5KW - Backlight but no image

12.58 volts on both sides of the fuse, 3ohm. Still trying to find f101 but it might take me a bit as I have the kids today.

[AFajitas]

Re: Westinghouse EW50T5KW - Backlight but no image

Just scanned the tcon multiple times with my super myopic vision and I can't find F101, there are even some components underneath, but no fuses.

[AFajitas]

Re: Westinghouse EW50T5KW - Backlight but no image

Tested the ohms again and I am getting 35.5, maybe I didnt have good contact before?

[selldoor]

Re: Westinghouse EW50T5KW - Backlight but no image

Fuse should be 0.0 ohms - the same as holding the probes together.
If you have same voltage both sides it should be good

[AFajitas]

Re: Westinghouse EW50T5KW - Backlight but no image

I am measuring the ohms without power, am I doing it wrong?

[CapLeaker]

Re: Westinghouse EW50T5KW - Backlight but no image

you cant do anything wrong by holding one probe on one end and the other probe on the other end of the fuse. Resistance should be very low. I say your first measurement is correct, the later not.

[AFajitas]

Re: Westinghouse EW50T5KW - Backlight but no image

Thanks. Is there a quick and dirty way to determine if the TCON is functional? I was thinking about unplugging the LVDS cable from the tcon while it's running to see if I get a flash or anything.

[selldoor]

Re: Westinghouse EW50T5KW - Backlight but no image

Not a good idea - are you saying the back light comes on and stays on?
Does the set remain responsive - you can switch on and off with remote?
Have you tried other inputs - dvd /PC etc

[AFajitas]

Re: Westinghouse EW50T5KW - Backlight but no image

Yes, responsive with the power button, backlight stays on the whole time TV is on. It really seems like it's working fine aside from the image being relayed to the panel. Today Im going to try something via hdmi and see if I can get sound. I ordered another tcon last night; for only 8 bucks it's worth it.

I'm also getting an oscilloscope, is this one good enough for troubleshooting LCD's? http://www.ebay.com/itm/Sencore-SC61.../221653635346?

[AFajitas]

Re: Westinghouse EW50T5KW - Backlight but no image

I replaced the TCON and got an image for a few seconds, but it seemed like it was only displaying every other row of pixels. After that, faint squealing sound and the smell of burning electronics, tcon no longer works. How can I begin to troubleshoot this? Checked my PSU voltages again and they are in spec.

[budm]

Re: Westinghouse EW50T5KW - Backlight but no image

It sounds like it has shorted IC line driver ICs (they are on the flexible PCB between the PCB and the LCD glass panel)

[AFajitas]

Re: Westinghouse EW50T5KW - Backlight but no image

Repairable? How can I check them. I'll post pictures of the driver boards.

[AFajitas]

Re: Westinghouse EW50T5KW - Backlight but no image

What can I test on this TCON board or the drivers to give me a clue as to what's going on?

[AFajitas]

Re: Westinghouse EW50T5KW - Backlight but no image

I noticed that the TCON mounts right to the metal case and just has a thin rubber/plastic square under the TCON where a few components reside. Is it possible I am shorting the TCON out on the case? I am half tempted to throw another 10 bucks down for a tcon board.