Vizio SV472XVT no video, but have sound

[mjastuart]

Hi,

thanks in advance for your help/advice.

We can power up/force power up the PC and can get sound, but no picture so we are assuming a problem with the backlight. we cannot get to bluescreen or see the menu and when we hook it up to cable the screen is dark gray.
in looking at the other postings and a number of videos on this topic, we started checking out the fuses and the voltage regulators on the main circuit board.

Fuse F4 was 11.90 and 11.88
Fuse F10 was 5.143 and 5.128
Fuse F13 was 5.145 and 5.141

we then moved on to the 3 voltage regulators we could spot on the main circuit board

U5
L501 G1117
pin 1 .270
pin 2 .433
pin 3 .004

U7
L501 G1117
pin 1 .000
pin 2 .000
pin 3 .004

U71
L501 G1117
pin 1 .000
pin 2 .000
pin 3 .067

this may be asking the obvious, but i am assuming i need to replace U7 and perhaps U71. I am a novice, so wanted to see if there was anything else i should check prior to proceeding with this replacement.

also, i contacted digikey to find out what i should order, and they could not find reference to L501 G1117. so if that is indeed what i need to replace, would appreciate any help on what to order.

many thanks again -- i have found the reference postings on here outstanding, and they gave me the confidence to try to fix this LCD TV.

Janis

adding link to service manual

[budm]

Re: Vizio SV472XVT no video, but have sound

Those regulators are not getting input voltage to them, you will need to find out where the b+ that feed the input pin of the regulator is coming from.

[mjastuart]

Re: Vizio SV472XVT no video, but have sound

Bud,

many thanks.

and any suggestions on what I should check next? should i test the output from the power supply board?

[budm]

Re: Vizio SV472XVT no video, but have sound

There are many fuses on that board, how is that black fuse F6? Can we get good focus shot pictures of the whole board both side and also in 1/4 section or less so we can easily see the components?

[mjastuart]

Re: Vizio SV472XVT no video, but have sound

Bud.

many thanks for the patience and advice. we went through and re-tested all fuses and voltage regulators on the main board, as we suspected we may have had only standby power on yesterday during some of our tests. The following readings are with the TV fully powered on, and we did see the blue glow of the backlight in the back of the TV, though the screen is still black in front when fully powered up.

Our validated results are as follows:

U5 L501 G1117
pin 1 2.069 (adj)
pin 2 3.309 (out)
pin 3 5.124 (in)

U7 L501 G1117
pin 1 1.251
pin 2 2.495
pin 3 5.125

U71 L501 G1117
Pin 1 2.062
pin 2 3.303
pin 3 5.084

U89 L501 G1117
pin 1 2.062
pin 2 3.305
pin 3 4.935

Fuses
F4 11.90
F6 5.130 (marked K)
F10 5.143
F11 3.340 (marked G)
F12 5.131 (marked K)
F13 5.145

So, with these readings, does it indicate anything we need to replace on this board? We noted that fuse U7 has lower readings, even though there is a 1.25+diff between adj and out -- should this be similar to the other voltage regulators as they are the same model, though adjustable?

Also any thing look unusual on the fuses? noted that one was a 3.3 v so don't know if that is ok.

Is there anything else you'd suggest we check on the main board, or does it look ok and we should move on to check something else.

many thanks for your continued help -- we are trying to save this TV from a rubbish heap and give it to our son for his 1st apartment.

thanks again!

janis

[budm]

Re: Vizio SV472XVT no video, but have sound

Regulators are fine, they are within 3%. At this point it points to the T-CON board may not be getting the voltage to it, it will be the board under the metal shield.
http://www.shopjimmy.com/lg-philips-...-con-board.htm
http://s807.photobucket.com/user/bud...?sort=3&page=1

[mjastuart]

Re: Vizio SV472XVT no video, but have sound

Bud,

many thx. i'll try ordering a board.

[budm]

Re: Vizio SV472XVT no video, but have sound

I would check the voltage on both ends of the fuse, it can be just blown fuse.

[mjastuart]

Re: Vizio SV472XVT no video, but have sound

ok will do and will let you know,
thanks!

[mjastuart]

Re: Vizio SV472XVT no video, but have sound

Bud,
fuse on the t-con board tested ok at 11.8 on both ends of the fuse.
should we also test the voltage regulator on the t-con board or do something else to see if it needs to be replaced

tx, Janis

[mjastuart]

Re: Vizio SV472XVT no video, but have sound

Bud,

Many, many thanks for the help in diagnosing the problem to the tcon board. installed the replacement board today, and the tv works perfectly.

many thanks for all the help.

Janis

[budm]

Re: Vizio SV472XVT no video, but have sound

Great news.

[zblad]

Re: Vizio SV472XVT no video, but have sound

I know this is an old thread but did you ever check the voltage on the regulator on the t con board? I am having the same issue and everything is identical to your unfortunately I don't know what the voltage on that regulator is supposed to be.

Thank You

[mjastuart]

Re: Vizio SV472XVT no video, but have sound

Hi,

Sorry, I never checked the voltage. Just replaced the tcon board with one I bought off eBay. Still working great.

[zblad]

Re: Vizio SV472XVT no video, but have sound

Alright so I got the same tv as you from a friend not sure if it has sound or not but when I plug it in it cycles orange and white vizio logo then after a minute its orange. I hit power it goes white and you can see the back lights working and if I hit the menu I cant see the menu but you can see that areas get brighter does this sound like the same issue to you? I checked all fuses and there good.

[newtothis]

Re: Vizio SV472XVT no video, but have sound

If backlights are on and tv stays on its probably the T-CON.

Plug in an input playing sound and cycle the Inputs until you can hear it... have sound?... Then replace T-CON