Vizio E55-E1 bad backlights or bad inverter?

[x_orange90_x]

I just got this tv today and it appeared to have no backlight on. After taking off the rear cover and checking again in the dark I can see that MAYBE one quadrant is lit.. But still it's quite dim. I was going to check the LEDs with my tester, and I found LED 1 and LED 2 + pins on the wire from the inverter, but I couldn't identify a ground. Nonetheless I tried using a mounting screw on the inverter board and also the chassis as ground but regardless my tester reads 300 which is what it reads when there is no voltage draw.

I don't know how exactly to test the inverter itself. Is it likely that 3 quadrants do in fact have bad leds? Or could the inverter be bad? I see backlights available on both SJ and eBay which is usually a good indicator that they are a common failure.

[nomoresonys]

I believe on this one, you would unplug connector cn801and put tester probes on pin 1 and 5, 3 and 5, 2 and 6, 4 and 6 of the connector and see if the backlights respond correctly.

[x_orange90_x]

I believe on this one, you would unplug connector cn801and put tester probes on pin 1 and 5, 3 and 5, 2 and 6, 4 and 6 of the connector and see if the backlights respond correctly.

Oh, I see what you're saying. But I'm thinking all 6 of those are positives, notice it's 6 brown wires. Also it says 1, 3, 5 = LED1_+ and 2, 4, 6 = LED2_+

If this we're the case there would 6 segments to the screen but I believe theirs only 4...

If what you said is correct then 5 and 6 have to be GROUND wires in order for it to be quadrants, but the wires shortly wouldn't be the same color as the positives 😧

After looking it up I don't there are 12 Active Zones... fwiw

[Diah]

socket must be unplugged

Vcc + are brown
Black are LED -

Odd Pins No (brown ) + to Odd Pins ( Black ) -
Even Pins No ( Brown )+ to Even pins ( black ) -

[x_orange90_x]

socket must be unplugged

Vcc + are brown
Black are LED -

Odd Pins No (brown ) + to Odd Pins ( Black ) -
Even Pins No ( Brown )+ to Even pins ( black ) -

So I can check 1, 3, and 5 to ANY of the odd numbered black wires on that connector? Likewise with 2,4,6 to even numbered black?

[Diah]

yes

[nomoresonys]

So was I right then?

[x_orange90_x]

I checked 1, 3, and 5 to pin 7... No voltage draw
I checked 2, 4, and 6 to pin 8... No voltage draw
I also tried to check them to pins 23 and 24, same.


I don't believe this test was accurate, because I know that at least once area lights up with the power on. Therefore at least one of the six words should have had draw on it. I did check these with it unplugged from the inverter.

[nomoresonys]

It's pretty basic right, here's a guy doing it with a diy rig, one probe to + and one to - https://www.youtube.com/watch?v=rNqRZ2qaDJY

[x_orange90_x]

It's pretty basic right, here's a guy doing it with a diy rig, one probe to + and one to - https://www.youtube.com/watch?v=rNqRZ2qaDJY

😂 This surely isn't my first rodeo. But it IS the first time I've tried checking backlights that have 2 dozen wires going to them! None of which actually say LED- or even ground for that matter.

[R_J]

Pins 7 and 8 are marked as NC (No Connection) look at the pin def. Pins 1,3,5 are VLED1_+ (from supply C8108/9) pins 2,4,6 are VLED2_+ (from supply 8209/12) All the other pins 9~24 are returns (led-) All 14 separate FB circuits have a mosfet and a source resistor as return to ground, each mosfet source also has a return (current Sense) back to the controller so it knows if a single string is open and likely shuts down all. Also the leds are controlled by the video that is displayed on the panel.
You likely have bad led's or maybe bad connections in the panel between the led strips and distribution strip.
14 strips, 6 led's per strip

Shopjimmy has the led strips, it looks like there are two different ones, so be sure to order the correct ones.

[x_orange90_x]

Pins 7 and 8 are marked as NC (No Connection) look at the pin def. Pins 1,3,5 are VLED1_+ (from supply C8108/9) pins 2,4,6 are VLED2_+ (from supply 8209/12) All the other pins 9~24 are returns (led-) All 14 separate FB circuits have a mosfet and a source resistor as return to ground, each mosfet source also has a return (current Sense) back to the controller so it knows if a single string is open and likely shuts down all. Also the leds are controlled by the video that is displayed on the panel.
You likely have bad led's or maybe bad connections in the panel between the led strips and distribution strip.
14 strips, 6 led's per strip

I just held the positive on one of LED2_+ pins and went along each of the black wire pins on the same side with the negative probe until I found something. When I touched Pin 16 FB9 I got 16.4v. so I checked the other 2 LED2+ pins and also got 16.4v. so that side appears to be working. I tried pin 15 FB10 with LED1_+ pins and got nothing. I suppose this means that side has bad LEDs.

[lotas]

Check the voltage here for each channel.

[nomoresonys]

I read it wrong, so 1,3,5 are vled 1 and 2,4,6 are vled 2.