Vizio E500i-B1 Backlight

[0S1R1S]

Re: Vizio E500i-B1 Backlight

Okay, so here's the latest update. I ordered a 24V 6 amp power adapter from Amazon and wired it in to the 24V outputs for the LED driver on the main board. Plugged in everything else, plugged in the set and turned it on, no backlight.
Then I plugged in the power adapter, and still no backlight, even with 24V going into the LED driver.
I know there is the one 24V rail coming FROM the main board to the power board, could that be my issue now?
I would just give it up and order a new power board and main board, but that would be an added cost of over $100 for parts alone and not worth it for this set.

[CapLeaker]

Re: Vizio E500i-B1 Backlight

The 24V runs the other way. 24V get generated on the PSU and feeds the main board on both connectors. The LED driver is on the main board. Did you check the backlight LEDs yet?

So... if you just unplugged one of the connectors and fed 24V, you also have to do that on the other one too. You also have to make sure the BLon voltage is present, which comes from the main board and gets looped trough the PSU and back to the LED driver on the main board (on/off). Back feeding 24V to the other 24V rail isn't that great idea if you left the 24V pins connected.

Problem is right now we have no clue how exactly you had the 24V hooked in to, if the on/off signal was present etc.

[0S1R1S]

Re: Vizio E500i-B1 Backlight

With the original power supply in the TV and no changes made at all, my friend hooked up his benchtop power supply set at 24V and injected 24V into just CN9102. Backlights came on, but they were flickering.
I ordered a replacement power board and installed it. Backlights came on but were flickering. I wiggled CN9102 and the flicker went away. May not have been correlated.
Turned the set on and off a few times, then lost backlights completely. The new power board will still power the set up just fine, but I've lost backlighting and the voltage has dropped from 24V to 15.5V.
I understand at this point it's most likely a fault of the main board damaging the power supply board, but how, I don't know.
Main boards are too expensive to install both into this set and still be a cost effective repair.
And yes, I know with Vizios, it's very common to have LED failure. At this point I'm thinking the set is beyond a cost effective repair and I should tell them to scrap it.

[CapLeaker]

Re: Vizio E500i-B1 Backlight

"I understand at this point it's most likely a fault of the main board damaging the power supply board, but how, I don't know."

because the LED driver is on the main board and not on the PSU or on a separate board.
Another cause could be that a failing LED (thus the flickering) actually did fail now and went open circuit, so the backlights are staying off. Also you have to make sure on/off (BLon) is sent from the main board, other than that the backlights stay off too.

[0S1R1S]

Re: Vizio E500i-B1 Backlight

"I understand at this point it's most likely a fault of the main board damaging the power supply board, but how, I don't know."

because the LED driver is on the main board and not on the PSU or on a separate board.
Another cause could be that a failing LED (thus the flickering) actually did fail now and went open circuit, so the backlights are staying off. Also you have to make sure on/off (BLon) is sent from the main board, other than that the backlights stay off too.

Okay. I understand that the LED driver is on the main board, it's the top left section of the board there. But how can that be the cause of damage to the power boards, that's what I'm curious about.

Anyway, current status is this. TV powers on. Backlight doesn't work with external or original power supply. 15.5V is there in place of 24V on the original power board still.

Thoughts on where to go from here?

[CapLeaker]

Re: Vizio E500i-B1 Backlight

what is printed on IC9103?

[tvtanner]

Re: Vizio E500i-B1 Backlight

The best way to check those two rectifiers is to replace them. I think that's your problem.

[0S1R1S]

Re: Vizio E500i-B1 Backlight

Problem was the main board. After ordering one and getting an incorrect part, I received the right one, and the backlights are now working just fine. Must have been an issue in the LED driver circuitry.

[CapLeaker]

Re: Vizio E500i-B1 Backlight

A1! Thanks for the feedback.

[RADIOTRON]

Re: Vizio E500i-B1 Backlight

I have a tv the same problem as this is but this is the catch if i put 24v external supply to the inverter the backlight turns on. I cant seem see a problem causing the power supply drop voltage. Even no load to it, it still 15v im reading.

[mmac1488]

Re: Vizio E500i-B1 Backlight

I have the same problem, 15v on all 24v pins on power board, but the tv works fine. After a couple weeks of using it, I went to use it one night and it wouldn't turn on. No backlights I mean. I brought it from home to my shop where I fix them and it's now almost a month later without a single issue, but still 15v everywhere it should be 24v. I want to double check everything before I sell it.

[mmac1488]

Re: Vizio E500i-B1 Backlight

I get 400v at the main caps, no change in voltage with main board, led connector or anything else unplugged.

[mmac1488]

Re: Vizio E500i-B1 Backlight

I do hear a very faint high-pitched sound from the area on power board where the side by side transformers are, but I've only noticed it since I've removed the board from the chassis and plugged it in. Any suggestions would be appreciated. I've been reading these threads for years now, you guys have walked me through quite a few repairs over the years. You guys are very, very much appreciated for your time and knowledge. Thank you

[keithsipa]

Re: Vizio E500i-B1 Backlight

I dont think it is a problem with the power supply. Had a problem with one of these not turning on when warm. The 15.6V on the 24V line has been reported in a few threads, the general consensus was a misprint on the board, I think.
This is what I had seen.
https://www.badcaps.net/forum/showthread.php?t=68882

Replaced the power supply fixed the problem for me, but the 15V on the 24V rail remained the same, even with the new board and the TV is still working like a champ.