Vizio va22lfhdtv10t no backlight.

[erickeri1234]

Picked up this vizio TV. It powers on flashes the screen but backlight isn't staying on. Checked with a flash light and was able to see the no signal image... Found one bad cap on the main board. Still no backlight. Changed the 2x 16v 470uf by the inverters but still nothing. I'm getting the correct voltage to the main board.. (12v and 5v) power and inverters are on the same board.
Thanks

[newtothis]

Re: Vizio va22lfhdtv10t no backlight.

What is happening to the BL_ON signal when the backlights cut off?

[budm]

Re: Vizio va22lfhdtv10t no backlight.

Any good clear pictures of the boards and how they are all connected together?

[erickeri1234]

Re: Vizio va22lfhdtv10t no backlight.

What is happening to the BL_ON signal when the backlights cut off?

I will check the bl_on.

[erickeri1234]

Re: Vizio va22lfhdtv10t no backlight.

Any good clear pictures of the boards and how they are all connected together?

The inverters are on with the power board. Will get pictures up soon

[erickeri1234]

Re: Vizio va22lfhdtv10t no backlight.

OK sorry for the late reply. I'm getting 4.9v on the bl_on signal wire.

[newtothis]

Re: Vizio va22lfhdtv10t no backlight.

Ok we need pictures now as budm asked

Can you list the voltages from the PSU - Main cable like this :

Pin 1 - PS_ON - 5v
Pin 2 - 5v STBY - 5v
Pin 3 - BL_ON - 4.9v

etc etc

Obviously the order of pin names will be marked on the board

[erickeri1234]

Re: Vizio va22lfhdtv10t no backlight.

Ok finally was able to get some pictures.

PIN 1 - PID - 5.0v
PIN 2 - Bl_on - 4.9v
PIN 3 - Bright - 4.6v
PIN 4 - 5v - 5.1v
PIN 5 - 5v - 5.1v
PIN 6 - Ground - Ground
PIN 7 - Ground - Ground
PIN 8 - Ground - Ground
PIN 9 - 12v - 13.3v
PIN 10 - 12v - 13.3v
PIN 11 EMPTY
PIN 12 - STandby - 0.0v

[jetadm123]

Re: Vizio va22lfhdtv10t no backlight.

Can you please post a good focused straight down photo of the bottom of the power supply board? There are some switching mosfets that should be checked.

[newtothis]

Re: Vizio va22lfhdtv10t no backlight.

Standby pin has no voltage yet the set is switched on?

[erickeri1234]

Re: Vizio va22lfhdtv10t no backlight.

Updated with more pictures

[erickeri1234]

Re: Vizio va22lfhdtv10t no backlight.

I just doubled checked the Standby volts and Still get 0.0v

[newtothis]

Re: Vizio va22lfhdtv10t no backlight.

Ok this makes no sense, Without the standby voltage the set would be completely dead.

Confirm you are testing using VDC and using the chassis as ground?

[erickeri1234]

Re: Vizio va22lfhdtv10t no backlight.

Ok this makes no sense, Without the standby voltage the set would be completely dead.

Confirm you are testing using VDC and using the chassis as ground?

Agree, I'm useing a fluke 115 on DC. I have to put ground on a heatsink. Power comes on front light is amber then lights up white when I hit the power button. I'm going to probe at it a little more in 10 minutes.

[jetadm123]

Re: Vizio va22lfhdtv10t no backlight.

When I said photos of the bottom of the board, I meant turning the board over. We need to see what's underneath. Your photos need to be in better focus.

[newtothis]

Re: Vizio va22lfhdtv10t no backlight.

Also use the chassis for grounding (Screw etc)

[budm]

Re: Vizio va22lfhdtv10t no backlight.

"PIN 12 - STandby - 0.0v" STBY on this board is the same as PS-ON pin, it is not being used on this board because this is an always on power supply.
There are two 8-PIN SMD power MOSFETs on the bottom side of the board that need testing as mention by the other.
Pictures are provided by SHOPJIMMY.

[erickeri1234]

Re: Vizio va22lfhdtv10t no backlight.

Can you please post a good focused straight down photo of the bottom of the power supply board? There are some switching mosfets that should be checked.

Sorry jetadm you did say bottom. I read it to fast.

[newtothis]

Re: Vizio va22lfhdtv10t no backlight.

"PIN 12 - STandby - 0.0v" STBY on this board is the same as PS-ON pin, it is not being used on this board because this is an always on power supply.

Cheers for clearing that up

[erickeri1234]

Re: Vizio va22lfhdtv10t no backlight.

"PIN 12 - STandby - 0.0v" STBY on this board is the same as PS-ON pin, it is not being used on this board because this is an always on power supply.
There are two 8-PIN SMD power MOSFETs on the bottom side of the board that need testing as mention by the other.
Pictures are provided by SHOPJIMMY.

OK I tested the two SMD power MOSFETS.
There are three of them The two I tested are close under the inverters. On both of them pins 1 throu 4 have 0.0 v , pins 5 throu 8 have 13.3v .