Vizio E70-E3 will not power up, no LED V.

[motterpaul]

Preamble: (skip if TL/DR)
This project started with a complete LED strips replacement because 6 of the 12 total strips were dim.

We replaced all 12 strips - then we put the TV back together and it will not turn on. As I said, I have standby voltage but no LED voltage anywhere in the TV.

I noticed the Power On button on the back of the TV was mashed down by the back cover, now one side of the button has broken off, It's just a piece of plastic that presses a metal button. All I could do was take that button off all-together and will use a pencil eraser if I ever need it.

NOTE: MY TV has only 4 LED voltage contact points on the power supply board. There are 12 LED strips total, but they fit together to go across the entire TV, so it is like 6 long strips. The dead strips (X) were arranged on screen like this. (We were hoping to fix this)

xxxxxxxxx000000000
xxxxxxxxx000000000
xxxxxxxxx000000000
000000000xxxxxxxxx
000000000xxxxxxxxx
000000000xxxxxxxxx

E70-E3 WON'T POWER UP

I also have a Vizio E70-E3 and I have a similar issue to Bobby G but different voltage issues.

On my Power Supply board, I have the correct standby voltage - 16V. But I have NO voltage going to the LED strips on this board and hence none on the mainboard. I tried disconnecting the main-board and remeasuring, but it made no difference in LED V.

With power connected my PSB V. are

LED OUT -- 00
LED OUT -- 00
LED OUT -- 00
LED OUT -- 00
gnd - 00
gnd - 00
gnd - 00
gnd - 00
+16VS = 16vs
AC-DET = 3.94v
PS-ON = -3.1 mv
+16VS= 16v
+16VS = 16v

I do have 110 V on hot side.

This is my power board: (plus my actual pictures are attached.

https://www.tvpartshome.com/wp-conte...9/01/57-23.jpg

[R_J]

Re: Vizio E70-E3 will not power up, no LED V.

Your fault is likely on the main board, you do not have the PS-ON voltage, this should likely be 3~5 volts. when the power button is pressed. If the power button is damaged (switch constantly pushed/shorted) it could be preventing the tv from turning on.

[motterpaul]

Re: Vizio E70-E3 will not power up, no LED V.

Your fault is likely on the main board, you do not have the PS-ON voltage, this should likely be 3~5 volts. when the power button is pressed. If the power button is damaged (switch constantly pushed/shorted) it could be preventing the tv from turning on.

It is stuck at -3.1 mv (I just fixed my post above).

Also - I have FIXED the power button issue now, it is not stuck in place. But it might have been pushed down when we first tried to repower the TV, and maybe put it in protection mode (?). One of my pics shows the actual power button now without the mashed button on top.

When we tried to turn on the TV nothing happened, though, no LED, no pops, no sounds, it was just dead. And I have tried some resets but it still won't power up. Maybe someone can recommend the best reset method?

Thanx for your help, now I know about PS-On. If I have voltage on PS-On does that mean the flashlight test should work?

[R_J]

Re: Vizio E70-E3 will not power up, no LED V.

But does the PS-ON voltage change? when the power button, or remote power button is pressed. The PS-ON could be 0 volts in standby, then 3 volts when the button is pressed. or could be 3v in standby and 0v when ON.

[motterpaul]

Re: Vizio E70-E3 will not power up, no LED V.

But does the PS-ON voltage change? when the power button, or remote power button is pressed. The PS-ON could be 0 volts in standby, then 3 volts when the button is pressed. or could be 3v in standby and 0v when ON.

Good question - no, it does NOT change (I just tested it). I was just going to try a 60-second reset (power out, button down 60 sec, power back in)

[motterpaul]

Re: Vizio E70-E3 will not power up, no LED V.

Sorry, meant to say it does NOT change

[motterpaul]

Re: Vizio E70-E3 will not power up, no LED V.

OK - I have the change what I said - after trying a reset - etc. Now the PS_on says -3.1 mv. Essentially zero. Sometimes if I hit the power switch it gets there from a different direction, but it always ends up at -3.1 mv.

Here is another update, after a reset I now have AC-DET = 3.94v

last update: But if I unplug the mainboard I get AC-DET = 4.43v

Top post has not been updated on last update

[motterpaul]

Re: Vizio E70-E3 will not power up, no LED V.

Based on no further replies, should I assume my friend R_J is correct and it is probably the mainboard?

All the research I did kept me thinking it was the Power supply board, but I am not an expert.

[R_J]

Re: Vizio E70-E3 will not power up, no LED V.

Well lets see, If you dont turn ON the power supply How do you expect it to have any other voltage than the standby voltage?
Disconnect the the power supply from the main board, Do you have a 3v battery around? if you do, connect the - to ground on the power supply and + to PS-ON and see if you get the LED_OUT voltage, If you don't have a battery try using about a 5k resistor between +16VS and PS-ON, this should also turn on the power supply.

[motterpaul]

Re: Vizio E70-E3 will not power up, no LED V.

I hate to sound dumb, but I have to... I did not know what those voltage abbreviations stand for - but I do now. I do have full sets of resistors so I will get one now and see what happens. Thanks for checking back.

[motterpaul]

Re: Vizio E70-E3 will not power up, no LED V.

Yeah - 57v - it works. So, not being a TV expert, I guess the easiest move now is to just get a new Mainboard?

I think I should replace the power button assembly, too. I can't find a way to test it.

[R_J]

Re: Vizio E70-E3 will not power up, no LED V.

The voltage abreviations are what is printed on the power supply board for the plug. On the button board, check the power switch with your meter, on those 4 lead tac switches 2 pins are usually common on one side, so check that it is not shorted (all 4 leads) then check if the switch works with yor meter. You could try disconnecting the button board but it looks like another board connects through it, likely the I.R. receiver board.
The main board might be having a problem with bga contacts on the large ic under the heatsink, or it might be an eeprom issue with the main board.

[motterpaul]

Re: Vizio E70-E3 will not power up, no LED V.

The voltage abreviations are what is printed on the power supply board for the plug. On the button board, check the power switch with your meter, on those 4 lead tac switches 2 pins are usually common on one side, so check that it is not shorted (all 4 leads) then check if the switch works with yor meter. You could try disconnecting the button board but it looks like another board connects through it, likely the I.R. receiver board.
The main board might be having a problem with bga contacts on the large ic under the heatsink, or it might be an eeprom issue with the main board.

Thanks again for your help! I knew the voltages were what was printed, I just didn't know what all the abbreviations meant. I happened to catch a video that explained PS-On just before you said the same thing here an hour ago.

Anyway - I tried testing the button, and nothing seems to change when I push it. If I knew a place to check it on the mainboard I could try that. There doesn't seem to be a lot of info out there, though. A replacement is only $10.

I hate to admit that I did not understand that your first reply was the answer until I tried the resistor, so I first ordered a new Power supply board. In addition, I already swapped out all the LED strips. (the original problem) I essentially replaced almost the whole TV.

I don't want to blow out my new LEDs, though, so I guess I will just replace all the parts - let me know if you think that is crazy. I have never worked with TVs so I don't know how temperamental they are...

[motterpaul]

Re: Vizio E70-E3 will not power up, no LED V.

by the way, the switch was sending voltage thru (IIRC about 2.2v) no matter what I did with it. All four points were not shorted (IIRC only one was ground) - so I could not determine either way from those tests. I will try to find another way to check that.

As far as knowing what PS_on meant, I guess I just figured the PSB fed the mainboard, and so the PSB it had to be the problem if there was no voltage there. Now I know better(I am used to analog circuits)

[R_J]

Re: Vizio E70-E3 will not power up, no LED V.

The PS-ON line is Power Supply ON. This power supply produces 16 volts but in standby, it is at a reduced current (it only has enough current to run the microprocessor basically ) When the PS-ON line goes high, the PFC circuit turns on, the U1 ic also comes out of burst mode so the 16 volts can now supply more current (for audio/video etc.) and the PWM for the backlight voltage turns on.
On the switch, there are 4 pins plus 2 shield pins. Pins 1&2 should be connected together, pins 3&4 are connected together. when the button is pressed pins 1,2 connect to 3,4. Pins 3,4 have a 0Ω resistor to ground. So if you check the voltage on pin1or2, and press the button that voltage should go to 0 volts.

[motterpaul]

Re: Vizio E70-E3 will not power up, no LED V.

The PS-ON line is Power Supply ON. This power supply produces 16 volts but in standby, it is at a reduced current (it only has enough current to run the microprocessor basically ) When the PS-ON line goes high, the PFC circuit turns on, the U1 ic also comes out of burst mode so the 16 volts can now supply more current (for audio/video etc.) and the PWM for the backlight voltage turns on.
On the switch, there are 4 pins plus 2 shield pins. Pins 1&2 should be connected together, pins 3&4 are connected together. when the button is pressed pins 1,2 connect to 3,4. Pins 3,4 have a 0Ω resistor to ground. So if you check the voltage on pin1or2, and press the button that voltage should go to 0 volts.

I will try this again, to the best of my memory from yesterday switching it did not connect all four pins together.

Where is the U1 IC located (which board, and is it surface mount or bigger?)

Also, how does one know what value resistor to use for the connection I made (5.1k) - does it vary by the TV and standby voltage?

[R_J]

Re: Vizio E70-E3 will not power up, no LED V.

The U1 is on the power supply (surface mounted), I refered to it only to explain what was happening on the power supply board. As for turning on the power supply, normally the standby voltage is +5 volts, so a 1k is safe, since this board uses 16 volts I suggested a 5k. The resistor is more for safety, incase you connect it to ground, you won't blow the standby supply, it is aslo to limit the current to the power supply control transistor.
In this tv the 16 volts is sent to the main board where it will be regulated down for the various voltages like 3.3 volts etc.
Some power supplies that Samsung uses, have pullup resistors, so simply removing the main board cable usually turns on the power supply.
It could be that the power switch is damaged and that is why the tv is not turning on?

[motterpaul]

Re: Vizio E70-E3 will not power up, no LED V.

I know from my guitar effects that LEDs will blow out (easily) if they get too much current, hence you add a CLR (current limiting resistor) to the voltage feeding an LED. The 5.1k gave me exactly 57v DC, which is pretty close to the actual voltage the board gives as far as I know (maybe it is closer to 59)

I wondered if you were familiar with my TV or if you just made an educated guess on the resistor.
Do you know the voltage of my individual LEDs (is it 3.3?), and also for my full strips? (there are 12 half-strips, (for 6 rows total), 9 LEDs per half-strip.

You have impressive knowledge. Is it all from experience, or is any of this information documented anyplace? (I have read it is not).

The setup is odd - the Power Supply board has four LED V feeds, but the mainboard has six (IIRC) sends and 12 grounds (for the LED strips).

The control buttons are hard to read consistently, I can get continuity tween 1-2 on the power button, but I can't get 3-4 to connect. That seems to work on the input button, though.

[R_J]

Re: Vizio E70-E3 will not power up, no LED V.

You don't seem to understand. the resistor was used to limit the current for the SWITCH TRANSISTOR that controls the optocoupler that turns on the power supply. it has nothing to do with how much voltage the led circuit outputs. you could have likely used a 10k (or a 3 volt battery for that matter) to turn on the power supply.

The setup is odd - the Power Supply board has four LED V feeds, but the mainboard has six (IIRC) sends and 12 grounds (for the LED strips).

Turn the power supply board over and have a look at it. It supplies 57 volts between two points, GND and the LED_OUT. You can have 1 fat wire or 4 thin wires, it is just to get the 57 volts from the power supply to the main board.
The led strips are all supplied +57 volts, then each of the strips have the negative side connected to a fet which controls the current to each strip. It looks like there are 12 control fets on this model, so I would guess there are 12 black wires from the panel. The first strip plug seems to have 3 connections, one + and two -. so I suspect each strip of 9 led's is controlled separately.

The control buttons are hard to read consistently, I can get continuity tween 1-2 on the power button, but I can't get 3-4 to connect. That seems to work on the input button, though.

ITS a SPST momentary switch, that's it. they use 4 contact points for better mounting

[motterpaul]

Re: Vizio E70-E3 will not power up, no LED V.

You don't seem to understand. the resistor was used to limit the current for the SWITCH TRANSISTOR that controls the optocoupler that turns on the power supply. it has nothing to do with how much voltage the led circuit outputs. you could have likely used a 10k (or a 3 volt battery for that matter) to turn on the power supply.

Well, I did not understand before, but I understand what you are saying. TVs, it's all new to me

Turn the power supply board over and have a look at it. It supplies 57 volts between two points, GND and the LED_OUT. You can have 1 fat wire or 4 thin wires, it is just to get the 57 volts from the power supply to the main board.
The led strips are all supplied +57 volts, then each of the strips have the negative side connected to a fet which controls the current to each strip. It looks like there are 12 control fets on this model, so I would guess there are 12 black wires from the panel. The first strip plug seems to have 3 connections, one + and two -. so I suspect each strip of 9 led's is controlled separately.

Everything you say here is also what I perceived to be the case. I just got on of those cool LED testers, and yes, the + side is for both sides of the connected strip, while 1 negative is for each of the 1/2-strips.

What I did not know before now is that one bad LED will take out an entire strip. When I saw YouTubes of guys replacing LEDs I thought they just had one dark spot in the backlight grid. Now I know better.

ITS a SPST momentary switch, that's it. they use 4 contact points for better mounting

OK, so if it momentary, I assume that means the only time I will see all four points as connected is when it is pressed down?