Vizio M502i-B1 won't turn on

[dskall]

Re: Vizio M502i-B1 won't turn on

Reread post 17. Need to find bl-on pin to see if it is giving command to the led board to turn on.

[Misterfixit]

Re: Vizio M502i-B1 won't turn on

Budwich:here is a picture of the on/off circuit board. For starters,the voltage on the two wires from the main circuit to the on/off board is 2.85volts. When the on/off button was depressed, the vintage drops to .3 volts. When the board is disconnected, the resistance on the two pins goes from infinte resistance to 479 ohms when the button is depressed. I suspect the zenor diode is open. I also drew a schematic of the board which I will send next

[budwich]

Re: Vizio M502i-B1 won't turn on

you might want to back up a bit... especially with amount of "misobservation / direction" as to what you have done / measured and on what board.

Further, as an aside, what is the history of the set / problem?

If I read your "results" correctly, the set thinks it has PS-ON... but it also has "dimming" set. Further, unplug the on-off button board. Get your meter and check what happens at the switch itself when the button is pressed... via resistance test on the contacts.

[Misterfixit]

Re: Vizio M502i-B1 won't turn on

Does anyone have any further suggestions/advice for me to try?

[Misterfixit]

Re: Vizio M502i-B1 won't turn on

I measured the on/off pin on connector cn9101 it was 1.14 volts. The voltage at this pin does not change whether the on off button is depressed or the remote control power button is depressed.

[dskall]

Re: Vizio M502i-B1 won't turn on

On your cn9101 connector what does your on/off pin measure?

[Misterfixit]

Re: Vizio M502i-B1 won't turn on

I stood the set up and repeated the flash light test with several flashlights. There is no video whatsoever when the set Is plugged in. I searched high and low for any legends on cable connectors between main board and led driver board for "bl-on" pin identification. There are no identifications on the cable for at either end.
There is a ten pin connector between the led driver board and main board, but there are no legends on either board to identify the "Bl-on" pin. At this time, I have no boast voltage on led driver board, no video, no working on off switch, no audio, not even a "on lite" when the set is plugged in (only a miniature "led401" that has a blue and pink color emitting from it in the main circuit board when set is plugged in). I have Low voltages (19.6 volts) on 24 volt power supply and 11.5 volts on 12 volt power supply rail. Unless, anyone has a another suggestion, should I consider purchasing a main circuit board or Led driver board? I would appreciate any advice at this time. Thank you

[Misterfixit]

Re: Vizio M502i-B1 won't turn on

Reply to dskall: thank you for pointing out that I had the wrong device completely. I feel pretty stupid. I thought the wi fi board was the ir sensor. I have now located the correct ir sensor on the set.(bottom right side of tv). For starters:The set does not have any buttons on the side or front of the set. Only button, is the On/off button which doesn't do squat. I have disconnected the wifi connector and tried to turn on set (nothing changed). I also, disconnected ir sensor and tried to plug in set, again nothing turned on. Here is a picture of the connector for the ir sensor. The following are the voltages on the 8 pins of the ir sensor.When monitoring voltages off of ir sensor board, the only change is on the red wire. It goes from 3.69 to 3.36 volts when the remote control power button is depressed. For what it is worth, any button depressed on remote makes voltage change to 3.36 volts on red wire.All other voltages on the other wires do not change.
Pin 1: purple wire - 0 volt
Pin 2: brown wire - 5.08 v
Pin 3 : red wire- 3.69 volts (changes to 3.36 volts when remote power on)
Pin 4: orange wire- 3.26 volts
Pin 5: yellow wire - 3.31 volts
Pin 6: green wire - 3.31 volts
Pin 7: blue wire - 5.08 volts
Pin 8: black wire (ground) -0 volts
I am going to stand tv up and do flashlight test and report back. Also going to try and find the bl-on pin. So far, I haven't spotted any ledgend for key1 or bl-on anywhere.

[dskall]

Re: Vizio M502i-B1 won't turn on

So you have checked with a flashlight and have no image on screen? You should have a connector running from main to led driver board with a pin for BL-ON. Have you checked that for voltage? You also have a connector that runs from your buttons to main. May say key1 or something on legend check those for varying voltage when you push buttons. Also your above picture looks like WI-FI unplug it and see if it works. For whatever unknown reason bad WI-FI can keep tv from coming on. Above board is for internet access and has nothing to do with remote or keys.

[Misterfixit]

Re: Vizio M502i-B1 won't turn on

Here is a close up picture of the board I thought was the ir sensor board. I now believe it to be a wi Fi sensor. I did verify that the second black wire does indeed go to ground.(by continuity check on ohm meter). With the hold down tape off, I was able to obtain correct voltages as follows:
Pin 1: Black 1 wire - 3.29 volts
Pin 2: black wire - ground (0 volts)
Pin 3: green wire - 3.25 volts
Pin 4: white wire - 0 volts
Pin 5: red wire - 5.07 volts
However, voltages do not change as a result of pressing power button on remote

[Misterfixit]

Re: Vizio M502i-B1 won't turn on

does anyone have any suggestions for what I should be trying next?
Thank you

[budm]

Re: Vizio M502i-B1 won't turn on

http://www.shopjimmy.com/catalogsear...Vizio+M502i-B1

[dskall]

Re: Vizio M502i-B1 won't turn on

That looks like WI-FI

[Misterfixit]

Re: Vizio M502i-B1 won't turn on

Here are pictures of both ends of connectir

[dskall]

Re: Vizio M502i-B1 won't turn on

Need picture of connector

[budm]

Re: Vizio M502i-B1 won't turn on

The output of the IR sensor is pulsing high frequency around 35~60KHz range (depends on IR system).

[Misterfixit]

Re: Vizio M502i-B1 won't turn on

On the IR sensor board, I have a connector that gas five wires. First wire(black) is 3.3 volts , second wire (black) is 0 volts, third wire (green) is 0 volts, fourth wire (white) is 0 volts and fifth wire (red) has 5.1 volts. Nothing changes (voltages stay the same) when I press the remote control on button. I am measuring these pins one at a time with the ground on the power supply ground connection at connector cn9101. Is there somewhere else I should be connecting my volt ohm meter Ground to or across to verify the if sensor board works?

[dskall]

Re: Vizio M502i-B1 won't turn on

You have a connector from your buttons, ir sensor etc. to mainboard. One or more pins should change voltage when you press buttons. Usually several pins will have around 3.3v check with voltmeter

[Misterfixit]

Re: Vizio M502i-B1 won't turn on

One other thing that is on my mind: the remote control doesn't seem to have any effect on the set when I push the power button on. I assume that the IR sensor is located on the lower right side of the set. I have replaced the batteries on the remote control and try to point it at the sensor while the tv is overhanging the table in which I am working on. (Set is screen facing down, but overhanging table so remote control hopefully will send signal to IR sensor). I have seen a You-tube video where a faulty IR sensor caused the set from turning on. The tech. Unplugged the IR sensor which caused the set to turn on. I also temporarily unplugged IR sensor cable and nothing happened. Is there something I can measure to assure that the remote control operation is working. When the remote control is operated, I don't even hear a click (from a relay) or anything went it is operated. Also, the TV set power button doesn't seem to function either. To engerize and shut off the set, I been plugging in the power cord. One other observation I noticed is, when the set is plugged in, there is a tiny led light that is on (it shines) located on the main circuit board

[budm]

Re: Vizio M502i-B1 won't turn on

"1. Is the boast voltage derived on the led driver board?" Yes, the yellow inductor is part of the boost converter circuit.
"2. I measured the voltage capacitors c820 and c821. The capacitor values and voltage rating cannot be seen unless I pull the caps off of the board to view the underside. What is voltage suppose to be on the capacitors c820 and c821? I measured only 19 volts. Is it suppose to be higher?" When the booster circuit is not turned on you will only see the feeding Voltage, in this case it is the 19V, those two should be rated at over 100VDC when it is running, the Voltage depends on how many LEDs there are in the LED string + Vdrops on the PWM controlled MOSFET and the current sensing resistor. Right now we do no know if the driver board is getting the BL-ON signal to turn on the boost converter circuit and the LED driver circuit or not, that is problem we need to find out.
You can spend $15 dollars on the driver board to find out if it is the board or something else.
http://www.shopjimmy.com/vizio-lntve...led-driver.htm
BTW, lately in the Vizio TVs we have found that what the Voltage printing the board does not really match what it is putting out.