AOC Envision LE24H067 Wont turn on at all

[tom66]

Originally Posted by kaks

So why am i not getting any Standby light when i plug the tv to the wall? if i press the volume channel keys there is power. the only thing it does is that it blinks as soon as i plug it in to the wall.

See above.

The fact that you get a brief standby light is encouraging. Usually a bad main board causes either no standby, or permanent standby, or sometimes the TV will exit standby (e.g. with a blue LED) but will stay there and will not turn off or show a picture.

[kaks]

i wrote it before i saw you response sorry ok i will upload the pics thankyou

[kaks]

OK hear is the pic of the switch board

i did a little test i disconnected the switch board and tried using the remote to turn on the tv. i measured the voltage on the IR pin and the voltage varies everytime i press any key on the controller. the voltage varies even hen i press the the power button. the voltage on IR pin reads 3.3v

[tom66]

Okay thanks for the pic.

Interesting that they would go for a surface mount design... is a bit more expensive than a through hole button board.

Anyway - To test the POWER button. Just try pressing it. Compare it to the others. Does it feel different? Does it get stuck down?

If the button feels good, another test is necessary. Using your multimeter, check the continuity of the pin I have highlighted to ground, both when depressed and when not. You may need an assistant. There is a hole called GND1, which you could use to put the black probe, then you would need a red probe on the pin highlighted and a finger to press the switch. The board *should not* be plugged in during this test. If you don't know how to test for continuity, make sure to ask first... post a picture of your multimeter too so we can see what setting to put it on.

If the value changes, then the button board can be ruled out for now.

Note - it's 10pm here so I'm going to bed soon. But there are many other people on this forum who can guide you through this...

[kaks]

I tested for continuity and yes the power button should be fine I used the diode tester mode on my multimeter I head sound everytime i pressed the pwr switch . i also tested the othe switches and they are all fine. What should be my next step please Thank you

[kaks]

Ok i tested the voltage of the PWR pin on the main logic video board and when i press the power switch the voltage goes from 3.3v to 0v just a note thanks

[kaks]

Ok so acording to my general understanding I get power all the way to the PWR but when I press the PWR button THe signal to start the tv does not get send. What could be the problem that that signal doesnt get trought?

[tom66]

Originally Posted by kaks

I tested for continuity and yes the power button should be fine I used the diode tester mode on my multimeter I head sound everytime i pressed the pwr switch . i also tested the othe switches and they are all fine. What should be my next step please Thank you

Okay switch board is good.

Next, some components on the main board need testing.

For each red component: I suspect these are LDOs or voltage regulators. Attach the black lead of the meter to an exposed metal portion of the case, excluding any heatsinks on the power supply. While the power is applied to the TV, test each pin and note down the voltage. There is usually a designator next to each component, such as U702; use this to refer to each component. There is no need to test the middle pin which is cut off. Note the part number e.g. "AP1117-33" which is on the LDO.

Confirm whether the component on the top right of the board which looks similar to the left red circled component has a designator beginning with "U". If so, that will need testing too.

For the blue circled diode: With the set *OFF*, use the diode test on your multimeter. Test both ways. You should get about 150 - 500 one way (or 0.150-0.500, depending on how your meter displays it) and 0L or "1." (or open) the other way. If not the diode is dud.

For each green component. These are inductors. First, with the TV unplugged, test for continuity (only necessary to test one way.) You should get a beep or dead short, or very low resistance. Next, with the TV plugged in, test the voltage on each exposed pin of each inductor. One end will measure 0V or some random value. The other end should measure a fixed, low and stable voltage. Note the voltage here. There is probably an identifier like "L123" next to each of these; use this.

Good night and happy testing...!

If any of these shows bad, you have a choice. You can replace it, but it will require a skilled hand at soldering. Or, you can replace the main board, *if* you can find a replacement.

[kaks]

hello i will do the testing as of to best of my knowledge I really apreciate your help thank you very much.

[kaks]

Ok i tested the diode you circuled blue and i get a reading of 158 one way and 1974 the other way around so acording to my understanding this diode is shorted?

[tom66]

Originally Posted by kaks

Ok i tested the diode you circuled blue and i get a reading of 158 one way and 1974 the other way around so acording to my understanding this diode is shorted?

It's probably okay; most likely the circuit is interfering with the measurement. Shorted is a reading less than about 50, and the same both ways.

[kaks]

ok the inductor have a voltage on both pins

the diode is fine as you said

the voltage regulators only the leg #3 of each regulator carries voltage

[kaks]

U708 carries 9.1v
U703 carries 5v
U702 carries 3.3v

[kaks]

Hello testing the inductors i get voltage both ways.

the 2 small ones have a low voltage like 2.3 and 3v and 5v and 4 on both sides

the biger inductor on the very top has a kind of high voltahe of aroun 9v one pin and 10v the other pin.
the gray inductor has a voltage of like 1.3 one pin and the other pin has like 2v

is this normal? you stated one side should have 0v on the inductors

[tom66]

Originally Posted by kaks

Hello testing the inductors i get voltage both ways.

the 2 small ones have a low voltage like 2.3 and 3v and 5v and 4 on both sides

the biger inductor on the very top has a kind of high voltahe of aroun 9v one pin and 10v the other pin.
the gray inductor has a voltage of like 1.3 one pin and the other pin has like 2v

is this normal? you stated one side should have 0v on the inductors

The values you are seeing are not what I expect but I am probably incorrect in assuming how this design works. If there's a voltage it's probably okay.

I don't really know what to suggest any more - is there a part number on the board? Some replacement boards are cheap. Others are expensive, it depends on the board. Then again a 24" LED TV is not a bad find, even if the board is £50 or so to replace.

[kaks]

hello where could be a good place to find Boards.

Also i want to make sure it is the main board?

according to what we have done do you really think its the board?

or could it be the LED laps?

could it still be the power board? I called AOC Envision and they can sale me the board for $102 usd

what do you suggest me to do?

I will post the pics of the main board as asoon as i get home from work

[tom66]

Originally Posted by kaks

hello where could be a good place to find Boards.

Also i want to make sure it is the main board?

according to what we have done do you really think its the board?

or could it be the LED laps?

could it still be the power board? I called AOC Envision and they can sale me the board for $102 usd

what do you suggest me to do?

I will post the pics of the main board as asoon as i get home from work

eBay is a good source, boards are usually pulled from broken TVs. (e.g. cracked screen.)

LEDs are very likely to be fine. They rarely fail. And besides, you have no audio, and the unit does not exit standby.

$102 is a rip off for a power board, and the power board is not the faulty board, as far as has been determined.

[kaks]

This are the numbers printed on the main video board

715G3759-MOF-000-005K is this the model number?

this is another number thats on a label on the board

(T)TQACB ZKD3502 TOP:A MB:A
S/N:1526730M0843 V2.02

[retiredcaps]

Originally Posted by tom66

$102 is a rip off for a power board

Especially, when a brand new TV is $159.

http://electronics.pricegrabber.com/...803065429.html

[kaks]

jajajajaja thats wright well guess im just going to have to give up on this junk i think its going directly to the trashcan jajajajaj