vizio vw37l turns on for a bit then turns off

[truep]

Re: vizio vw37l turns on for a bit then turns off

Sounds like you don't have 24V going to the inverter. Do you have the 12V and 24V at the power supply? Also, take a look at the IC just below and between the caps. A common failure has a pin burnt ayay due to shorted FET's

[budm]

Re: vizio vw37l turns on for a bit then turns off

OK, I went back and read through post1 and looked at the pictures, right now the main board is not sending the ON signal to the ON/OFF pin of the power supply board to turn on the 12v/24V power supply.
You will need to check and report the DC voltage reading so of the voltage regulator ICs which more likely to be the problem in the main board. See the link below my signature on how to test the LDO.

[asdfjkljkl5]

Re: vizio vw37l turns on for a bit then turns off

Here are the voltage regulator test results.

U16 -> pcb designation
AZ7805T -> line 1 of the IC
-E1 -> line 2 of the IC
744D58 -> line 3 of the IC
pin 1 = 0
pin 2 = 0
pin 3 = 0

U22 -> pcb designation
J501 -> line 1 of the IC
G1117 -> line 2 of the IC
pin 1 = 2.07
pin 2 = 3.31
pin 3 = 5.03

U19 -> pcb designation
J501 -> line 1 of the IC
G1117 -> line 2 of the IC
pin 1 = 1.25
pin 2 = 2.50
pin 3 = 4.98

U15 -> pcb designation
J501 -> line 1 of the IC
G1117 -> line 2 of the IC
pin 1 = 2.06
pin 2 = 3.30
pin 3 = 4.98

U17 -> pcb designation
J501 -> line 1 of the IC
G1117 -> line 2 of the IC
pin 1 = 2.07
pin 2 = 3.32
pin 3 = 4.98

U21 -> pcb designation
J501 -> line 1 of the IC
G1117 -> line 2 of the IC
pin 1 = 0
pin 2 = 1.25
pin 3 = 2.49

U20 -> pcb designation
J501 -> line 1 of the IC
G1117 -> line 2 of the IC
pin 1 = .55
pin 2 = 1.80
pin 3 = 3.28

U44 -> pcb designation
"backward c" "vertical line" "vertical line" 7JA -> line 1 of the IC
1117L -> line 2 of the IC
pin 1 = 0
pin 2 = 0
pin 3 = 0

The markings on this one were weird. I attached a picture of the markings.

[asdfjkljkl5]

Re: vizio vw37l turns on for a bit then turns off

Will replacing the main board solve my problem? If so I think I will buy a new one. Thanks for all the help.

[asdfjkljkl5]

Re: vizio vw37l turns on for a bit then turns off

It looks like to me that power is not getting to everything on the board (based on my results above), so I think I will trace where everything is going and see if that solves my problem. Maybe I just have to replace a simple part.

[asdfjkljkl5]

Re: vizio vw37l turns on for a bit then turns off

I have tried tracing out what is happening on the main board but it is too small to work with. Since I do not know if these voltage regulators are the problem, I am considering buying the entire new main board. Do you suggest that I buy the new one, or is one of the voltage regulators bad? Does anyone else have any suggestions to try?

[asdfjkljkl5]

Re: vizio vw37l turns on for a bit then turns off

Also, budm said that signal was not going to the on/off pin, so could I artificially introduce that signal? Could I just connect a battery to that pin? What voltage would I need to supply?

[tom66]

Re: vizio vw37l turns on for a bit then turns off

Around 3V.

[asdfjkljkl5]

Re: vizio vw37l turns on for a bit then turns off

That solved it, I connected 2 AA batteries to the on/off pin and the screen turned on. I am looking for a resistor that I can run from one of the 5 volt pins to the on/off pin so that I don't need the battery. Is there a better solution than that? Can I still fix my main board?

[asdfjkljkl5]

Re: vizio vw37l turns on for a bit then turns off

Does anyone know the current on those 5 volt pins?

[tom66]

Re: vizio vw37l turns on for a bit then turns off

Couple of mA. 100 to 470 ohm resistor works fine.

[asdfjkljkl5]

Re: vizio vw37l turns on for a bit then turns off

I jumped a 150 ohm resistor from one of the 5 volt pins to the on/off pin and it makes the TV turn on to a blue screen. When the tv is on standby (the amber light is on and the screen is off) but the resistor is still connected, power is still going to the inverter board, therefore i put a switch on the resistor and stuck it out the side of the tv. When I want to put it into standby now, I have to press the power button and switch off the resistor.

When I hooked it up to my computer via hdmi, it just kept searching for a signal. I believe that the hdmi parts of the main board must have gotten ruined and that caused a signal not to be sent back to the power supply to turn on the tv. However, the D-sub (vga) connector works fine for displaying picture.

Maybe in the future I will replace my main board, but it is working fine right now. Once I get to college, I will be able to troubleshoot it more.

Until then, thanks everyone for all the help.

[budm]

Re: vizio vw37l turns on for a bit then turns off

Just curious, what voltage do you get now on those regulators since some of them were showing 0v?