Vizio V047L-FHDTV30A - No Backlight, sound, or picture

[beuford318]

Hello,

I am a long time lurker, first time poster and I have a Vizio V047L-FHDTV30A that has no backlight, sound, or picture. The Vizio logo at the bottom turns from orange to white and then nothing. It will stay like that for as long as you let it sit. There are no bulging caps or obvious defects. It will power on/off from the side button but the remote does not work.

I have searched and searched and it is hard to find information on this exact model. I found a few people that had similar issues with the FHDTV20A and FHDTV10A's but it seems those models are a little different on the inside.

I have a multimeter and know how to use it but without a manual I am just measuring stuff with no progress.

Any ideas?

I have attached a picture of the board layout. The T-con is above the power board under the metal plate. I can take more high-res pics if needed.

Thanks in advance.

[budm]

Re: Vizio V047L-FHDTV30A - No Backlight, sound, or picture

You have power supply/backlights inverter combo board. On the bottom right of that board, there are two connectors, we need good clear pictures of those connectors so we can see what the pins are labeled with some kind of voltage/name of the pins. Right now the standby power supply is working.

[beuford318]

Re: Vizio V047L-FHDTV30A - No Backlight, sound, or picture

budm,

Thanks for the quick reply. Here is the picture you requested.

I had to take it on my work iPhone as it seems to take better pictures than my personal Android. I AM NOT a fan of Apple products though. That is a rant for another day.

I can take some 12mp pics with a real camera if need be ;-)

Regards,
beuford318

[budm]

Re: Vizio V047L-FHDTV30A - No Backlight, sound, or picture

OK, Pin 3 of CN201 is the signal receiving pin that turn the backlights inverter circuits ON/OFF, the signal is generated by the Main board, it should be >3VDC or more for ON, .5VDC or less for OFF. Don't know what the VBRA is, see if it changes state when TV is OFF and when TV is ON. I do not see PS_ON signal pin, it is used to turn on the Main 12/24VDC power supply ON.
And also check the Voltage regulator IC on the main board as suggested by retiredcaps.

[retiredcaps]

Re: Vizio V047L-FHDTV30A - No Backlight, sound, or picture

Some Vizios are notorious for having bad voltage regulators. See my sig on how to test them. List all your results following the format in my guide.

There are also tons of threads regarding this issue.

[beuford318]

Re: Vizio V047L-FHDTV30A - No Backlight, sound, or picture

I got .09v at pin 3 on standby and 2.91 - 3v at power on. vbra does not have a wire from the mainboard.

Thanks,
Beuford318

[budm]

Re: Vizio V047L-FHDTV30A - No Backlight, sound, or picture

3V should be enough to turn on the Inverter. Do you get 24VDC on the small connector next to the large connector?

[beuford318]

Re: Vizio V047L-FHDTV30A - No Backlight, sound, or picture

Retiredcaps,

I will look down circuit for a bad reg and post back.

Thanks,
Beuford318

[beuford318]

Re: Vizio V047L-FHDTV30A - No Backlight, sound, or picture

Budm,

No, I can't get any voltage at all on that set.

[budm]

Re: Vizio V047L-FHDTV30A - No Backlight, sound, or picture

There is a large cap laying side way between the heatsink, it is in the primary side which is DEADLY, you need to get DC meter and read the voltage on its two legs when the TV is plugged in but NOT TURN ON, the reading should be about 165~170VDC, when the power switch is activated, the voltage should go up to around 390~400VDC. You will have to find the way to measure that voltage safely, I would highly suggest you to plug the TV into GFI outlet to protect yourself, do not touch any heatsink or any parts in the Primary side with your hands or any part of your body.

[beuford318]

Re: Vizio V047L-FHDTV30A - No Backlight, sound, or picture

Budm,

That cap is pushing 169VDC on standby. No change when powered on.

Thanks,
Beuford318

[beuford318]

Re: Vizio V047L-FHDTV30A - No Backlight, sound, or picture

retiredcaps,

Here is the breakdown on the regs from the mainboard taken at standby. All measurements in VDC except where noted.

U21
K393
G1117
pin1 = 0
pin2 = 1.25
pin3 = 3.31

U20
1084
0810FL
pin1 = .55
pin2 = 1.8
pin3 = 3.31

U15
1084
0810FL
pin1 = 2.08
pin2 = 3.33
pin3 = 4.99

U19
1084
0810FL
pin1 = 1.25
pin2 = 2.5
pin3 = 5

Q19
C5886
85?
pin1 = 1.5mv
pin2 = 1.5mv
pin3 = 1.3mv

I also attached some better pictures taken with a real (consumer grade) camera.

Thanks

[budm]

Re: Vizio V047L-FHDTV30A - No Backlight, sound, or picture

If you do not have the 400VDC on that cap and the board does get the INVERTER on signal OK, that means the power supply board is not working, the Inverter circuits need the 400VDC to run, same for the 24VDC output.

[retiredcaps]

Re: Vizio V047L-FHDTV30A - No Backlight, sound, or picture

Q19
C5886
85?
pin1 = 1.5mv
pin2 = 1.5mv
pin3 = 1.3mv

All the voltage regulators look good.

Q19 is a NPN transistor. See

http://pdf1.alldatasheet.com/datashe...SC5886_06.html

Carry on with budm's suggestion on the PFC side.

[beuford318]

Re: Vizio V047L-FHDTV30A - No Backlight, sound, or picture

All,

I ordered a replacement board for $65 shipping included. That is a steep discount from the $120 vizparts wanted and completely within my comfort level.

I will post back the results when the board comes in.


Thank you,
Beuford318

[beuford318]

Re: Vizio V047L-FHDTV30A - No Backlight, sound, or picture

Tested "Good" Board came in today. I swapped them and no change. I still have 3vdc on the inverter turn on and no 24vdc on the other side. I still get 170VDC on the big cap at standby and no change when powered on. No backlight... Vizio Logo still turns white and powers off from side button.

Could this board also be bad? I suppose it is possible. There is an audible high pitched whine at standby that the old board did not have. Is there something we missed or another route to test? I double checked all the connections and they are solid.


Thanks in advance,
Beuford318

[budm]

Re: Vizio V047L-FHDTV30A - No Backlight, sound, or picture

"There is an audible high pitched whine at standby that the old board did not have" Well, that does not sound normal.

[jdunn5]

Re: Vizio V047L-FHDTV30A - No Backlight, sound, or picture

beuford318, did you ever get a resolution or any farther on this issue. I have the same model and issue. I have replaced that main board and tried 3 different tcon boards. I get the same high pitch squeal from the tcon board after pressing the power button. I can make the squeal stop by disconnecting the connector from the main board to the tcon board. I have not had much luck in finding what is causing the issue.

budm,
Have you heard of that before?

Thanks
Jason.