Vizio SV470M Standby, no power on, troubleshooting trouble

[budm]

Re: Vizio SV470M Standby, no power on, troubleshooting trouble

That sounds like the same problem I am having with the Vizio VO370, the processor is running hot even in standby, I cannot put my finger on the heatsink for more than 10 seconds. Right now we already know that the Main board is not sending the Inverter on tothe power supply-inverter board, so the main board is having problem and we are trying to find out if the power supply-inverter is OK or not since you will not want to get new main board and then find out that the power supply-inverter board is also bad.

[Srimps]

Re: Vizio SV470M Standby, no power on, troubleshooting trouble

This is the exact problem I am having right now with the SV470M. Orange light is on but won't power on. I checked my voltages on the power supply board and got pretty close to what you are reading. Mine started to flicker on and off at a low frequency then all of a sudden cut out and wouldn't turn back on.

I updated your original post below with what I got for readings:

On the powerboard:
I have standby 5v from the three "ST/+5V" tabs on the powerboard to the main.
I have 12v at the three tabs on the same plug labeled "12v".
I have 2.69 v at the tab on the same plug called "on/off."
All the grounds on this plug are clean to ground.

The plug next to it with Dim, Inv Com, VBR_A, Status, AC Det, are all dead.

Wish I could help out but I'm in it to see what you find out.

[redheaddiesel]

Re: Vizio SV470M Standby, no power on, troubleshooting trouble

Bud, I jumped 5v via ik resister to Inv_On as you instructed and the backlights came on.

Also, I tried the AC detect and it has no voltage no matter what. When I hit the power button there is nothing anywhere, no click, no nothing.

Hoping this paves the way to either the next step of troubleshooting or tells us which board and/or component is bad?

Thanks again,

Matt.

PS, why did we send 5v via a 1k resistor and not just straight wired?

[redheaddiesel]

Re: Vizio SV470M Standby, no power on, troubleshooting trouble

Thanks Srimps. Good to know I'm not alone. Hopefully we'll make some progress and figure out what we have.

[budm]

Re: Vizio SV470M Standby, no power on, troubleshooting trouble

Ok at least we now know that the backlights inverter is working OK and also the power supply, so right now the board is sending out the PS_ON to the power board OK but not sending the Inv_ON (BL_ON) to turn on the backlights. Since now you do have the backlights on the panel, do yo see any pictures on the screen, if not, that means the main board is not working.

[redheaddiesel]

Re: Vizio SV470M Standby, no power on, troubleshooting trouble

Thanks, Bud. Just to make sure I understand, I should put that jumper back on the Inv_on to power up the backlights, then look at the screen for a picture, or a menu screen or something? Now if the power is still off, should I expect to see anything?

If it is confirmed to be the main board, is there anyway to troubleshoot this to the component level, or should I just get another board.

If I go the board route, what do you think of getting a used board on ebay?

Thanks again,

Matt

[redheaddiesel]

Re: Vizio SV470M Standby, no power on, troubleshooting trouble

I can also confirm that there is nothing on the screen besides the backlight when I jump that power over. Again, though, there is no way to power on the TV, so it seems to me that I shouldn't expect to see anything, right?

[budm]

Re: Vizio SV470M Standby, no power on, troubleshooting trouble

OK, you need to keep that resistor in place for the BL_ON pin, then hit the power switch and see if the the PS_ON does go up when you hit the power switch, the TV may be automatically turn itself on when you plug the cord into the AC outlet. If you do see PS_ON >3V, then hit the power switch to turn off the TV, if the PS_ON stays at >3V, that means the main board is stuck and not functioning.

[redheaddiesel]

Re: Vizio SV470M Standby, no power on, troubleshooting trouble

Bud, Just to clarify, I'm going to use the jumper wire with resistor to send 5v to the BL_ON tab and then examine the PS_ON tab voltage as I plug in the TV. If I see >3v, then I'll hit the power button and see if it changes voltage. Am I reading you right?

[redheaddiesel]

Re: Vizio SV470M Standby, no power on, troubleshooting trouble

Bud, I'm just now examining the board, and not seeing a BL_On tab. Might it be called something else? See post #22 for the list of tabs.

mm

[budm]

Re: Vizio SV470M Standby, no power on, troubleshooting trouble

the 'INV_ON' one as you can see, not INV COM.

[redheaddiesel]

Re: Vizio SV470M Standby, no power on, troubleshooting trouble

Bud,

I jumped 5v to Inv_ON via 1k resistor. Plugged in the TV while taking a reading on the On/Off tab and it stayed 2.74v the entire time, even when hitting the power button. I'm thinking that maybe you wanted me to do something different, but I don't see a BL_ON or a PS_On. Am I missing something? Sorry.

Matt.

[redheaddiesel]

Re: Vizio SV470M Standby, no power on, troubleshooting trouble

I ordered a used board on eBay for $45. I hope it will confirm that the main board is the problem. I'd still like to troubleshoot the main board I have, though, so if anyone has any input or clarification based on my last couple of messages I'd sure appreciate it.

Thanks,

Matt.

[MisterD]

Re: Vizio SV470M Standby, no power on, troubleshooting trouble

I had a similar problem with a 37" Vizio, I tried to re-flow the processor on the main board with a heat gun but got it too hot and now it is damaged, so I ordered a replacement board on ebay and fixed the set that way..these processors use a BGA ( Ball Grid Array) method to connect them to the main board, each pin at the bottom of the processor sitting on a ball of solder to make the electrical connection, after many hours of operation and heat the connections can separate causing the processor to not operate correctly or not at all..By using lots of liquid flux and placing the board in an oven you could possibly re-flow the BGA to the Processor with the risk of damaging the board or causing the solder balls to short together, if it does short circuit without your knowledge and then you re-install it(the mainboard) you risk damaging the power supply board because of the short circuit, The processor on mine was also hot to the touch, I'm not sure if that is the problem with your main board but it's possible. I wouldn't even attempt to re-flow the processor without finding the exact instructions on how to do it properly, if you do a search on the internet you will see that it can be done with the proper and very expensive equipment.

Check out this link for more information..
http://www.etech-web.com/bga-reballing.htm

[redheaddiesel]

Re: Vizio SV470M Standby, no power on, troubleshooting trouble

The board that came is the wrong one. Grrrr. I'm tempted to try the reflow. This guy has done a lot of laptops using the foil/heat gun method. He's got some tricks that seem to minimize damage. What do you guys think of it?

http://hardforum.com/showthread.php?t=1531323

[tom66]

Re: Vizio SV470M Standby, no power on, troubleshooting trouble

For these Vizios it appears to mostly be firmware problems now... reflowing isn't going to fix anything.

[redheaddiesel]

Re: Vizio SV470M Standby, no power on, troubleshooting trouble

Thanks Tom. Is a firmware issue something that can be fixed?

[tom66]

Re: Vizio SV470M Standby, no power on, troubleshooting trouble

Only if Vizio publish the firmware, but you'd still need a flash programmer.