42" Vizio No Picture has Backlight

[MisterD]

This is a newer LED/LCD TV, has LED for Backlighting and an LCD Display Panel.
It does power on but has no display, has only a blank grayish screen with no video, I tried hooking up a dvd player as a source but since I can not see any images on the tv screen I can't tell what input mode is selected. with this set is was easier to measure voltages on the small fuses on both the Mainboard and T-Con Board. instead of measuring at the power supply connectors and taking a chance on the meter probe slipping and shorting out.
It has all dc voltages present, 5 volts, 12 volts and 18 volts. I measured these on both sides of the fuses to ensure the fuses are good as well as voltages being present. I noticed that the processor under the metal shield on the mainboard is generating some heat so hopefully it is working, but the heat sink on the T-Con stays cool even after leaving the set on for over 1 hour. I removed and reinstalled the T-Con board therefore re-seated attached ribbon cables and visually inspected the board. At this point I think the T-Con board has failed and is causing the problem, I do have another posting on this set but could not edit the heading or delete the post and I felt like the heading was misleading. Model Vizio XVT3D424SV. please reply back, your help is appreciated. Thanks!

[XmouseX]

Re: 42" Vizio No Picture has Backlight

Pictures of the main board? Also have you checked the Voltage regulators on the main board?

[MisterD]

Re: 42" Vizio No Picture has Backlight

Pictures of the main board? Also have you checked the Voltage regulators on the main board?

Being a newer set this main board does not have the typical AMC1117 Voltage regulators, here's some pictures I found on the net of the same exact boards this set uses. I have only checked the voltages on the fuses.

[MisterD]

Re: 42" Vizio No Picture has Backlight

Being a newer set this main board does not have the typical AMC1117 Voltage regulators, here's some pictures I found on the net of the same exact boards this set uses. I have only checked the voltages on the fuses.

More Main Board Pictures

[XmouseX]

Re: 42" Vizio No Picture has Backlight

Sorry to ask, but can I get a close up picture of the area where the back light cable plugs in. Like a 2 inches perimeter around the connector. Also are all your surface mounted fuses good?

[MisterD]

Re: 42" Vizio No Picture has Backlight

Sorry to ask, but can I get a close up picture of the area where the back light cable plugs in. Like a 2 inches perimeter around the connector. Also are all your surface mounted fuses good?

The backlights are working and they are LED, they are powered directly from the power supply board therefore there's no need for inverter boards. Do you still want a close up picture of where the back light cables plugs in?
Thanks!

[MisterD]

Re: 42" Vizio No Picture has Backlight

Okay, I seem to be at a Stand Still with this one, being a newer LED TV, I'm not getting much help. I went ahead and ordered a replacement T-Con Board in hopes that it will fix my problem. Thanks.

[MisterD]

Re: 42" Vizio No Picture has Backlight

Question: If the backlights are working and the LCD Panel is not doing anything, does it still let the backlight shine through to form a white or grayish screen? in other words does the LCD Sceen have to be working in order to see anything such as a white display with no picture? or is that just the backlight you see on the screen?

[budm]

Re: 42" Vizio No Picture has Backlight

You can easily verify that by disconnecting the cable to the LVDS cable from the T-CON.
http://s807.photobucket.com/albums/y...t=DSCF1912.jpg
But the high contrast screen, you may not easily see the glow.

[MisterD]

Re: 42" Vizio No Picture has Backlight

bud, can you tell me which cable or cables to disconnect from the T-Con ? here are more pictures from my actual tv I'm working on. Thanks.

[budm]

Re: 42" Vizio No Picture has Backlight

Not sure if the backlights will still come on if you remove the LVDS cable and the power cables.

[MisterD]

Re: 42" Vizio No Picture has Backlight

I also tried to get sound by hooking up a dvd player to the RCA Composite and audio input jacks and pushing the input button on the remote control but no results, but I did notice the brightness change while pushing the remote input button several times.

[budm]

Re: 42" Vizio No Picture has Backlight

If you have backlights which its job is for the light source only so you can see pictures on the screen, the it sounds like the T-CON may be bad or video processing may be bad, but since you are not getting the sound (not 100% sure) then the main board may have problem, it can be FIRMWARE is corrupted or bad EEPROM. I wish I have the answer.

[MisterD]

Re: 42" Vizio No Picture has Backlight

If you look at the bottom of the mainboard just above the RGB Connector there are small black plastic squares the one on the left is labeled "audio" it's a small audio jack the one on the right has a gray cover over it and it is labeled "optical" when I push the input selector on the remote there is a red light behind the gray cover on the optical jack, if I leave the input so the red light stays on the tv will shut itself off in 1 minute or less, I'm not sure why and was also wondering what the small audio jack is for? Thanks

[MisterD]

Re: 42" Vizio No Picture has Backlight

If you have backlights which its job is for the light source only so you can see pictures on the screen, the it sounds like the T-CON may be bad or video processing may be bad, but since you are not getting the sound (not 100% sure) then the main board may have problem, it can be FIRMWARE is corrupted or bad EEPROM. I wish I have the answer.

The T-CON board I ordered is on the way, I should get it soon, I hope that will fix it, I will keep you posted. Thanks.

[budm]

Re: 42" Vizio No Picture has Backlight

That is what is called TOSLINK using Optical (light source such as red LED you are seeing) for digital audio. The small 3.5mm AUDIO may be for the PC Audio input which is close to tghe PC VGA connector.
http://en.wikipedia.org/wiki/TOSLINK

[MisterD]

Re: 42" Vizio No Picture has Backlight

That is what is called TOSLINK using Optical (light source such as red LED you are seeing) for digital audio. The small 3.5mm AUDIO may be for the PC Audio input which is close to tghe PC VGA connector.
http://en.wikipedia.org/wiki/TOSLINK

Okay, Thanks!

[MisterD]

Re: 42" Vizio No Picture has Backlight

If you have backlights which its job is for the light source only so you can see pictures on the screen, the it sounds like the T-CON may be bad or video processing may be bad, but since you are not getting the sound (not 100% sure) then the main board may have problem, it can be FIRMWARE is corrupted or bad EEPROM. I wish I have the answer.

Hi Budm, After trying different input sources again I did get sound, I'm using a dvd player with composite video/rca jacks/audio in, since there is no video and you can't see what input you select I figured out each time you push the input button on the remote it takes at least 7 seconds to take affect so I actually would do this, push input on the remote wait 10 seconds, push input again and wait 10 seconds, I kept doing this and eventually got the right one and Bingo we have sound. Now I'll be real glad to get my new/used T-Con Board. Thanks again.

[budm]

Re: 42" Vizio No Picture has Backlight

How expensive is the T-CON?

[MisterD]

Re: 42" Vizio No Picture has Backlight

$54.99 Free Shipping from E-Bay.