Need help with Vizio E3D470VX

[joeshannallie]

Picked up a Vizio E3D470VX and the guy said he heard a pop and that was it. Well when I push the power button the Vizio logo will come up and go right back off. Can still turn it off and on with power button. Took the back off and this is what I found. The mosfet is popped open and apart. Could this be the problem? The number on the mosfet is NDF05N50ZG. I looked the part number up and this is what I found that it is a MOSFET NFET T0220FP 500V 5A 1.5R. Can someone search on radioshack.com for mosfet 500v and see if what they have will work. Please reply soon.

[MagicSmoke]

Re: Need help with Vizio E3D470VX

Digikey has the exact part you need. http://www.digikey.com/product-searc...GOS-ND&stock=1

.94$ for one.

[budm]

Re: Need help with Vizio E3D470VX

You need to find out if the Gate drive circuit is direct drive to those two MOSFETs, if it is, then you will need to replace the driver IC and the Gate drive components.
You need to check them out real well otherwise you will blow up your new parts.

[joeshannallie]

Re: Need help with Vizio E3D470VX

Would you care to give some advice on how to do what you are saying? It would be much appreciated.

[CapLeaker]

Re: Need help with Vizio E3D470VX

post a pic of the back side of your board.

[budm]

Re: Need help with Vizio E3D470VX

Good clear straight shot pictures of the whole board, both sides.

[joeshannallie]

Re: Need help with Vizio E3D470VX

Here is the pic, best I could do. No burnt marks or anything on the back side of the board.

[joeshannallie]

Re: Need help with Vizio E3D470VX

Lets try again.

[budm]

Re: Need help with Vizio E3D470VX

My post #6 "Good clear straight shot pictures of the whole board, both sides."
I need to be able to see the traces so I can trace the connections from point A to point B,
I do not have the board in front of me to see.

What can be done when good clear pictures are provided:
https://www.badcaps.net/forum/showpo...5&postcount=35
https://www.badcaps.net/forum/showpo...9&postcount=12

[joeshannallie]

Re: Need help with Vizio E3D470VX

I will upload some better ones in a few minutes.

[joeshannallie]

Re: Need help with Vizio E3D470VX

This the best I can get, I really appreciate you Bud

[budm]

Re: Need help with Vizio E3D470VX

OK, it is transformer coupling for driving the MOSFETs, on the GATE pin, there are 3 components (2 resistors, 1 diode)connected to it, check them out.
Look up the spec of the MOSFET to get the pinout.
BTW, there are FOUR MOSFETs,
Too bad they install a jumper wire in place of the fuse F400 which feeds B+ to that inverter circuit.

[joeshannallie]

Re: Need help with Vizio E3D470VX

Replaced the mosfet and it still has the same problem. When you first turn it on the Vizio logo will appear and then it is gone. But the screen seems to not light all the way up. Then a few seconds later the screen will light back up and then go right back off. You can turn it off and on with the remote. Does anyone have any ideas. Could it be the main board or a tab bond issue. If it was a tab issue would the screen stay lit and on?

[CapLeaker]

Re: Need help with Vizio E3D470VX

the LCD and the backlight are 2 different circuits. Hook up your meter to the brown big 450V cap, turn the TV on and see what it does. It should have 170V then ramp up to 380V. That indicates the PFC is working.

[budm]

Re: Need help with Vizio E3D470VX

OK, it is transformer coupling for driving the MOSFETs, on the GATE pin, there are 3 components (2 resistors, 1 diode)connected to it, check them out.
Look up the spec of the MOSFET to get the pinout.
BTW, there are FOUR MOSFETs,
Too bad they install a jumper wire in place of the fuse F400 which feeds B+ to that inverter circuit.

Replaced the mosfet and it still has the same problem. When you first turn it on the Vizio logo will appear and then it is gone. But the screen seems to not light all the way up. Then a few seconds later the screen will light back up and then go right back off. You can turn it off and on with the remote. Does anyone have any ideas. Could it be the main board or a tab bond issue. If it was a tab issue would the screen stay lit and on?

So what happen to the MOSFETs and the Gate components testing?

[joeshannallie]

Re: Need help with Vizio E3D470VX

Sorry Bud but I dont really understand how to test what you are telling me to test.

[CapLeaker]

Re: Need help with Vizio E3D470VX

That mosfet you changed out, download the data sheet and see on which pin the "gate" is. Look that up on your board. There are components inline. Resistors, diode etc that go back the driver IC. If a gate circuit component is bad, the mosfet simply won't work. Verify the resistor values, what's printed on it, to what it actually measures. So usually resistors either go open or get higher resistor value, that's bad. Diode usually shorts or gets leaky, that's bad too.
Budm told you already what to check, read post #12 again. You may have to "lift" one leg to get good measurement out of circuit.