Vizio VL470M, White Logo, No Backlights, Sound, or Picture.

[johnboy1313]

The logo comes up white as soon as the set is plugged in. The PSU shows all expected voltages as if it's working as it should. Both fuses have correct voltages at both ends. All 1117 voltage regulators appear to be correct. The large regulators don't appear out of sorts. There is a 1122 regulator that I'm not familiar with.

ADJ = 1mV
OUT = 1mV
IN = 89mV

Right now, I'm suspecting EEPROM issues. Any thoughts? Is there any more testing I can perform?

[tom66]

Re: Vizio VL470M, White Logo, No Backlights, Sound, or Picture.

Is BL ON/OFF (INV_ON) going HIGH or not?

[johnboy1313]

Re: Vizio VL470M, White Logo, No Backlights, Sound, or Picture.

No, but I can force the lights on with resistors.

[tom66]

Re: Vizio VL470M, White Logo, No Backlights, Sound, or Picture.

On the bottom of the board can you trace the track going out of "IN" on the suspect regulator?

[johnboy1313]

Re: Vizio VL470M, White Logo, No Backlights, Sound, or Picture.

Here's a pic. The IN leg of the regulator comes through at the tip of my lead in the picture. I've tried to make a video. I'll post a link if YouTube lets me.

[johnboy1313]

Re: Vizio VL470M, White Logo, No Backlights, Sound, or Picture.

Here's the video.

https://www.youtube.com/watch?v=P_rPWHuGIZw

[johnboy1313]

Re: Vizio VL470M, White Logo, No Backlights, Sound, or Picture.

Any ideas?

[tom66]

Re: Vizio VL470M, White Logo, No Backlights, Sound, or Picture.

It looks to me like the trace is buried in the board, so that is difficult to trace without schematic. All main board fuses OK?

[johnboy1313]

Re: Vizio VL470M, White Logo, No Backlights, Sound, or Picture.

They appear to be. I'll have another look.

[johnboy1313]

Re: Vizio VL470M, White Logo, No Backlights, Sound, or Picture.

All main fuses that I see check good. I rechecked the 1122 regulator and I'm seeing about .65V at the IN pin now. I would guess that really doesn'r make much difference.

[tom66]

Re: Vizio VL470M, White Logo, No Backlights, Sound, or Picture.

Try seeing if (with set powered off) if there's an obvious short between IN and ground using an ohmmeter.

[johnboy1313]

Re: Vizio VL470M, White Logo, No Backlights, Sound, or Picture.

There doesn't appear to be. It starts at 0.000 but slowly climbs to .562k ohms

[tom66]

Re: Vizio VL470M, White Logo, No Backlights, Sound, or Picture.

Hard without a schematic to see where that's going to, the best you could do is try ohming it out but there's hundreds of possibilities...

[johnboy1313]

Re: Vizio VL470M, White Logo, No Backlights, Sound, or Picture.

When comparing my main board

http://www.shopjimmy.com/vizio-3647-...for-vl470m.htm

to one from a different 47" Vizio with the same PCB number

http://www.shopjimmy.com/vizio-3647-...for-sv470m.htm

It looks like the section of the board that I'm focusing on is T-con related. If I can't figure out what's wrong with this board, this set may have to sit until I can find parts.

[johnboy1313]

Re: Vizio VL470M, White Logo, No Backlights, Sound, or Picture.

I bought a used board from a seller on eBay. it showed up with the co-ax connector on the tuner broken off. I emailed the seller for an exchange. They offered a $30 discount if I wanted to try to fix that board with the tuner from my board. I removed the tuner from my board and was kinda surprised to see burn marks at the back side of the co-ax input. I thought maybe the tuner was shorted and keeping the set from powering on. Unfortunately, that wasn't the case. With the tuner removed, my board still doesn't work. I didn't think a $30 discount was enough to risk damaging the new board and considering the old tuner looks to be damaged, it looks like the old tuner wouldn't work anyhow. I'm guessing a lightning strike through the cable input took this one out. Pics attached.

[tom66]

Re: Vizio VL470M, White Logo, No Backlights, Sound, or Picture.

You could have found the source of damage to the original board - power surge through tuner can. I would not use that tuner can either.