Visio V755-G4 LED TV: No backlight, have sound, see menu with light.

[Grasshopper2Ant]

No backlight issue. Have sound and can see menu with flashlight.

Suspect LED driver, voltages are 100V each side. What should the voltages be for 75 inch TV on the Power Supply Board? I have 96 leds x3 volts per=288/2=144 volt per side?
Am I low on my volts causing the leds not to light up?

Before I got all backlights out, the right side was a bit darker than left side. How many leds
need to be out for all to not work?

Thinking of getting a led tester. If leds light up, would that confirm it is the Power Supply Board?

I do not want to dismantle entire board to get at leds at this time and hope to diagnose it is not.the PSB

Thanks for any help guys!.

[diif]

Re: Visio V755-G4 LED TV: No backlight, have sound, see menu with light.

It's LEDs not driver.

[Grasshopper2Ant]

Re: Visio V755-G4 LED TV: No backlight, have sound, see menu with light.

Thanks for reply. Anyway to confirm this 100%.

[Grasshopper2Ant]

Re: Visio V755-G4 LED TV: No backlight, have sound, see menu with light.

No backlight issue. Have sound and can see menu with flashlight.

Suspect LED driver, voltages are 100V each side. What should the voltages be for 75 inch TV on the Power Supply Board? I have 96 leds x3 volts per=288/2=144 volt per side?
Am I low on my volts causing the leds not to light up?

Before I got all backlights out, the right side was a bit darker than left side. How many leds
need to be out for all to not work?

Thinking of getting a led tester. If leds light up, would that confirm it is the Power Supply Board?

I do not want to dismantle entire board to get at leds at this time and hope to diagnose it is not.the PSB

Thanks for any help guys!.

Here is similar board as mine. Can someone tell me how many volts I should be getting at the two LED driver connects on 75 inch Vizio?

Also, I am getting a 300V led tester. If the leds light up on both connects, would that confirm it is power supply board?

Thanks for any help!

[Grasshopper2Ant]

Re: Visio V755-G4 LED TV: No backlight, have sound, see menu with light.

Power Supply board at LED driver connectors on and off board with power plugged in.

180 plus volts at connectors and board at start-up and dwindles to 100 volts in 5 seconds.

No Vizio logo or backlights.

Is this a normal board booting up?

I am resided to it being backlights but still want to do the 300V LED tester test.

[Grasshopper2Ant]

Re: Visio V755-G4 LED TV: No backlight, have sound, see menu with light.

Dismantled the TV.
Tested the LEDs with tester. 2 rows consisting of 6 leds each side are out. That is 24 leds out.
Trying to take the reflector sheet off but it is glued to the leds.
How does one deal with the reflector sheet without tearing it. Very poor design by Vizio.
Anyone else have this problem and how did you solve it?

[nomoresonys]

Re: Visio V755-G4 LED TV: No backlight, have sound, see menu with light.

That sounds pretty odd, post a good picture of this.

[Grasshopper2Ant]

Re: Visio V755-G4 LED TV: No backlight, have sound, see menu with light.

The led strips are glued to the back as well as the reflector.

I decided to cut the reflector around the leds. Lots of extra bullshit but once I carved out the first one I used it as a template for the rest. Tedious but just get a rhythm going.

A strip with 6 leds measure 34V on my tester.

Ordering a set and update later.

[bscottjohnston]

Re: Visio V755-G4 LED TV: No backlight, have sound, see menu with light.

Dismantled the TV.
Tested the LEDs with tester. 2 rows consisting of 6 leds each side are out. That is 24 leds out.
Trying to take the reflector sheet off but it is glued to the leds.
How does one deal with the reflector sheet without tearing it. Very poor design by Vizio.
Anyone else have this problem and how did you solve it?

Wondering if a heat gun on low or a hair dryer might get the sheet out without damage. On my 70" Vizio with the panel out the LEDs would start up and I could see which ones were damaged without the tester.

[nomoresonys]

Re: Visio V755-G4 LED TV: No backlight, have sound, see menu with light.

Could use a hairdryer, not too hot of a setting but most will peel right off with steady slow pulling, did a big vizio the other day, each led had it's own little screw beside it holding the sheet in place, have not seen that very often.

[Grasshopper2Ant]

Re: Visio V755-G4 LED TV: No backlight, have sound, see menu with light.

Thanks for tips guys!I

I looked at a shop Jimmy video and he cut it out with Olfa razor blade.

That is what I did. 16 strips. Top 4 rows had screws on LED strips, bottom 4 was glued with white thermal tape.

To put back new strips I used double sided thermal tape and on reflector edges and installed.

As a tip, buy or source the tape beforehand. I could not find it anywhere at any

Ordered on Amazon. Cheaper if you have time to get from Aliexpress.

Anyways, all was good till I messed up install which I will start a new thread for help.

[Grasshopper2Ant]

Re: Visio V755-G4 LED TV: No backlight, have sound, see menu with light.

The LEDs I had on my strips were all out on the bad rows, 4 rows.

I replace bad ones with existing good ones and all light up. I did same to other side and all lit up.

I tested a strip and I could not get one individually to light up with my new led tester.

Probably testing it wrong.