vizio sv320vxt no video

[nosaj]

I have a vizio sv320vxt no video, whne you turn it on the vizio logo shows then disappears. Checking voltages the power supply caps c3 and c4 are getting 335 vdc. J1 pins 10 and 11 5 volts pin 12 3 volts should be 5. This is possibly where I think problem is but not sure what to replace.

J1 pins 2 3 4 12 volts.
U1 pins 5 6 7 8 is 5vdc
U2 pin 2 3.3vdc
U9 pin2 1.9VDC
U4 pin2 1.25 VDC
FB75 8+vdc
CE82 1.08VDC

Can anyone help me? I hooked up a hdmi connection and I get audio no picture.

Thanks,
Jason

[leggot]

Re: vizio sv320vxt no video

Check to see if its a backlight inverter issue, the easiest way is to turn the set on and shine a flashlight into the screen to see if the picture is still there, if it is it is an issue with the inverter or backlight.

[nosaj]

Re: vizio sv320vxt no video

I can see the picture using a flashlight. On the invertor board I have 24.2 volts at the test points VB22
and VBL1.
Status test point is 5.4 YBR- b is 2.0 on/off is 1.6.

Should I see if voltages change when unpluggling CFL connections?

Thanks,
Jason

[leggot]

Re: vizio sv320vxt no video

I would first visually inspect the inverter boards to ensure that there is no visual damage, there is information on this forum called 2 seconds to black: https://www.badcaps.net/forum/showthread.php?t=10419

In these cases the main board senses something wrong with the inverter circuitry and chooses to shut down the circuit, thats why the backlight is only on for a couple seconds.

This should give you a good idea of how to test the inverter boards. Typical things to check are open fuses on the inverter board, bad transformers (tests described in link) and bad solder joints. If this is not your issue, it may be a connection issue to the actual CCFL.

[nosaj]

Re: vizio sv320vxt no video

I think that is a bad link. I did search for the 2 seconds to black and don't seem to be finding what your referencing.

The invertor board looks ok.

Jason

[leggot]

Re: vizio sv320vxt no video

The link got cut off, its fixed now. If you have detailed pictures of the inverter board, please post them. Check the fuses, if they are bad the resistance should be OL or 1

[nosaj]

Re: vizio sv320vxt no video

Here are the pics.
Fuse on Invertor board is good.

Thanks,
Jason

I'll go through the doc when i get a chance...

Merry Christmas

[budm]

Re: vizio sv320vxt no video

https://www.badcaps.net/forum/attach...1&d=1419464668
Please take the DCV readings of all those test points copper pads and make sure to list each name of the pad with the readings.
Take the reading when TV is OFF and when power switch is activated.

[nosaj]

Re: vizio sv320vxt no video

Ok here goes, I did no list pads with no reading. the transformer look to not be passing any voltages.

Thanks,
Jason
and Merry Christmas

no voltages in Off position
in ON position

PD 2.7
VREF 5.5
QV 4.5
AD 2.2
CT 1.2
UVL 2.8
H1 2.1
H2 2.8
STATUS 5.39
VBR-B 2.81
ON/OFF 3.23
VBR-A 1.62
VBL2 24.3
VBL1 24.3
VPS 3.0
VPC 3.0

[budm]

Re: vizio sv320vxt no video

OK, the inverter is getting the 24Vdc for power and also BL_ON (ON/OFF) to turn on the inverter circuits but it is still not working, so it can be bad inverter board (bad MOSFETs, transformers, capacitors) or bad lamp assemblies.

[nosaj]

Re: vizio sv320vxt no video

Checking resistances on Q1-through Q4

Q1 .663 1.08
Q2 .670 1.30
Q3 .663 1.08
Q4 .670 1.30

So to me it seems replacing the Invertor board is the way to go but that I might still have bad lamp assemblies? This can't be tested without a working invertor correct?

Thanks,
Jason

[budm]

Re: vizio sv320vxt no video

You will have to take the panel apart (very delicate job) to see the lamps and lamp's connections to see if it has any sign of worn lamps, bad lamp's socket, etc.

[nosaj]

Re: vizio sv320vxt no video

Is there a link somewhere that gives a general teardown and what I might be looking for( example of what a worn lamp looks like) , as well as what to be careful of?

Thanks,
Jason

[budm]

Re: vizio sv320vxt no video

http://www.shopjimmy.com/catalogsear.../?q=6632L-0568
It usually means that this is common failure board so SJ does not have them in stock.

[nosaj]

Re: vizio sv320vxt no video

i found this one if its a reputable company http://www.tvpartscentral.com/lg-663...ight-inverter/

But before throwning money out there on something that may not be the entire problem I'd like to check the panels and cfl tubes if you know of a resource.

Thanks,
jason

[budm]

Re: vizio sv320vxt no video

I cannot really tell you how to take the panel apart, I never write the instructions since each panel is not the same as how they are put together.