Vizio E400I-B2 powering on problem

[budm]

Re: Vizio E400I-B2 powering on problem

OK, that means the 32VDC is normal then,, those caps are the filter caps for the output of the Boost converter circuit that boosts the incoming 24VDC to higher level for running the LED string, and you are getting about 8VDC on the Cathode side of each LED strings so it sounds like the MOSFET for each of the LED current return lines are not being turned on.

[budm]

Re: Vizio E400I-B2 powering on problem

What is the LCD panel model number? There should be a sticker some where on the back of the panel.

[CapLeaker]

Re: Vizio E400I-B2 powering on problem

May not be just like the other one a while back with the missing BLon signal?

[budm]

Re: Vizio E400I-B2 powering on problem

I believe I saw another thread with similar board that I could find out which pin are for BL-ON, Dimming, etc. I think the BL-ON is present otherwise he will not have that boosted 32VDC.

[nwcs]

Re: Vizio E400I-B2 powering on problem

I have the exact same results with the exact same model tv. I do not think the led's are the problem. I believe the main board is the culprit. I Checked voltages on cn201 both while on and while powering on.
while on: 1 and 2 are 5v, 3 is 3.3v and all of the 12v are 0v.
While powering on the 12v all read 12v then go down.

[nwcs]

Re: Vizio E400I-B2 powering on problem

I forgot to mention pin 4 is 0v while on and 3v when turned on.

[budm]

Re: Vizio E400I-B2 powering on problem

So you do have PS-ON (3 VDC) on pin 4 when TV is turned on but you are not getting the switched 12 Vdc, you have problem with the power supply.

[nwcs]

Re: Vizio E400I-B2 powering on problem

Just tested all of the LED's and all lit up fine. I am leaning on a bad main board.

[nwcs]

Re: Vizio E400I-B2 powering on problem

I get 12v when turned on but then it goes to 0v.

[budm]

Re: Vizio E400I-B2 powering on problem

If pin 4 3V is present and stays at 3V or so but the switched 12V drops out then you need to check that 12V section to see if it being loaded down, or bad parts, etc.

[nwcs]

Re: Vizio E400I-B2 powering on problem

So you are saying power supply. I will check in the morning.

[budm]

Re: Vizio E400I-B2 powering on problem

We need good clear straight shot pictures of your power supply board top side and the bottom side.

[CapLeaker]

Re: Vizio E400I-B2 powering on problem

or something connected to the 12V rail on the PSU loading it down.

[TheCockroach]

Re: Vizio E400I-B2 powering on problem

I have the exact same results with the exact same model tv. I do not think the led's are the problem. I believe the main board is the culprit. I Checked voltages on cn201 both while on and while powering on.
while on: 1 and 2 are 5v, 3 is 3.3v and all of the 12v are 0v.
While powering on the 12v all read 12v then go down.

Kind of good to know that I'm not the only one with this problem, but it also kinda sucks. Means there's probably a lot of others as well, as it may just be an inherent flaw with this particular model.

We need good clear straight shot pictures of your power supply board top side and the bottom side.

Maybe I should leave the picture taking to nwcs, since it'd seem my camera produces really poor quality results. if he can't get back to us with some, then I'll borrow a friends phone to take pics with instead.

[budm]

Re: Vizio E400I-B2 powering on problem

So did you at least check the resistance of the 12V pin against GND to see if it shows really low resistance?

[TheCockroach]

Re: Vizio E400I-B2 powering on problem

So did you at least check the resistance of the 12V pin against GND to see if it shows really low resistance?

Which board is that on again btw, the main board (aka, same one that I took the LED measurements off of, or..) ?

[nwcs]

Re: Vizio E400I-B2 powering on problem

It has been off my bench for a while but I think it was the power supply.

[nwcs]

Re: Vizio E400I-B2 powering on problem

OK, I have three of these TV's in same issue. I got a used main board off ebay and still have same problem. I did check to see if there was anything displayed on the screen (hit the menu button and used a flashlight to look) and there is nothing. I have verified all led's are at least lighting and the measurements were taken off of the power supply.

[TheCockroach]

Re: Vizio E400I-B2 powering on problem

OK, I have three of these TV's in same issue. I got a used main board off ebay and still have same problem. I did check to see if there was anything displayed on the screen (hit the menu button and used a flashlight to look) and there is nothing. I have verified all led's are at least lighting and the measurements were taken off of the power supply.

Any word from your end, about what the problem with these TV's was/is, by chance..?

[nwcs]

Re: Vizio E400I-B2 powering on problem

Sorry, I thought I had already posted the repair. On this model it ended up being the power supply had failed, just like budm had thought. I had a E420i-A0 with almost the same problem and it ended up being the main board.