AOC Envision LE24H067 Wont turn on at all

[kaks]

Hello im new to this forum so please if im in the wrong section direct me please.

OK so here i go?

I picked up this LED tv at a flea market thinking it would be an easy fix but i have spent over 2 days trying to figure out the problem but cant seem to find it.

Syntoms: When i plug the power cable to the wall outlet i just see the standby light blink once and then stays of and never turns on again. I dont hear any kind of sound or any other thing.


Things done: I have been focusing on the Power board thinking this is the problem but i have found nothing.

I used my multimeter to test out the voltage outputs pins of the power board and this are the results of the printed volts on the board.

Labeled

(GRD) = ok
(GRD) = ok
(+16v) = ok i get 16.2v
(+16v) = ok i get 16.2v
(+5.2) = ok i get 5.2v
(+5.2) = ok i get 5.2v

There is a pin called 0/F and another named DIM. those are not outputting any voltage

the backlight pin volts dont match the voltage labeled could this be the Problem?

labeled

(42.9v) I get 16v on my multimeter
(42.9v) I get 16v on my multimeter


All caps seem to be fine from my view there are no signs of bubble heads or drains.

There is a Yellow transformer that has one side all legs are like burned with some yellow stuff. Could that be bad? would i still be getting voltage out of the power board like a i do if that transformer was bad?

I Have attached some pics to give you guys an idea of my situation.

Hope you guys can help this newbbie

All suggestions are welcomed. Thank you

[kaks]

Re: AOC Envision LE24H067 Wont turn on at all

this are the fotos

[PlainBill]

Re: AOC Envision LE24H067 Wont turn on at all

1. Borrow or buy a better camera.

2. Use the better camera to take Several pictures - a picture of the top of the power supply, a picture of the bottom side of the power supply, one of the top side of the main board, and one over-all shot of the back of the TV.

PlainBill

[kaks]

Re: AOC Envision LE24H067 Wont turn on at all

Here are the better pics thank you

[Mad_Professor]

Re: AOC Envision LE24H067 Wont turn on at all

Can you also list the capacitor values, please?

Example:
Series, Temp Capacitance, Voltage, diameter and height, lead spacing if possible
KZG, 105*C, 1000uf, 35v, 12.5 x 20mm, 5mm

[retiredcaps]

Re: AOC Envision LE24H067 Wont turn on at all

Schematic at (by searching for 42.9V envision)

[kaks]

Re: AOC Envision LE24H067 Wont turn on at all

Ok the brown capacitors on the top left are:

2x elite 120uf 63v Ep(m)105 degrees pet (c)1016
1x elite 270uf 25v Eh(m)105 degrees pet (c)1016


the capacitors in the top middle of board are

brown 1x elite 270uf 25v Eh(m)105 degrees pet (c)1016
orange 2x elitegp 68uf 25v 120
orange 1x elitegp 470uf 10v 120
black 1x elite 470uf 16v

and the one farthest to the right is a

1x elite 47uf 35v 105 degrees c

and the last 2 long ones on the bottom right are

2x 100uf 220v pz(m)105 degrees c

this is all the information that reads each capacitor

1x 2x etc. means number of capacitor with does values thank you

hope someone can help me please.

[PlainBill]

Re: AOC Envision LE24H067 Wont turn on at all

retiredcaps, thanks for the link to the schematic. That may help make up for the lack of good pictures.

Kakz, The pictures don't quite cut it. The schematics that retiredcaps found help, but I'm getting a sore neck trying to read the schematics sideways. Yes, the absence of the 42.9 volt rail is significant.

Possible suspects are IC904, Q920, D913, R951, and the enable signal at IC904, pin 13. Of these, IC904, pin 13 is most likely the problem. Verify that pin 1 of CN902 reads 0 volts. If it does, the problem is on the main board. If it reads 5 volts, the problem is on the power supply card.

PlainBill

[kaks]

Re: AOC Envision LE24H067 Wont turn on at all

Ok i verified pin 1 of CN902 and it reads 0v i did the test using just the power board connected to wall i disconnected the digital video board . please guide me what should i do next i have attached some new pics please see them. Note that on the connector of the digital video board there are 2 pins that say 24v and those two pins go connected to the powerboard and on the powerboard it is label 16v and i tested the voltage and i get 16.45 v

[PlainBill]

Re: AOC Envision LE24H067 Wont turn on at all

Ok i verified pin 1 of CN902 and it reads 0v i did the test using just the power board connected to wall i disconnected the digital video board . please guide me what should i do next i have attached some new pics please see them. Note that on the connector of the digital video board there are 2 pins that say 24v and those two pins go connected to the powerboard and on the powerboard it is label 16v and i tested the voltage and i get 16.45 v

You will have to do the test with the main board connected. It took some time to study the schematic; it's poorly drawn and loaded with errors. Apparently the same raw board is used to make at least three different finished power supply / LED drivers. Two of them have extensive circuitry to drive LEDs. The version you have is quite simple. The On/Off signal comes from the main board. When it goes high a DC-DC converter starts which boost 16.2 V to 42.9V. The DIM signal, 42.9V, and GND are sent directly to the LED strips.

I suggest hooking a signal source (DVD player, video game) to the TV inputs, turning the TV on, and stepping through the inputs until you hear the audio. Sometimes you can see an image if you shine a bright light on the screen (I've never been able to get this to work). If you can't hear the audio, the main board is definitely bad. I wouldn't be concerned about the mismatched labels; this is obviously a lash-up design.

PlainBill

[kaks]

Re: AOC Envision LE24H067 Wont turn on at all

Hello thanks for your time. Well i did the test with the main board connected and i still dont get any voltage reading from Pin 1 of CN902.
I also tested the tv connecting a dvd player and i couldnt hear anything.

Does this all mean I have a bad video logic board?
is there a way i can fix it?


What is my next step please?

[kaks]

Re: AOC Envision LE24H067 Wont turn on at all

Ok here is a pic of of the connector on the main logic video board this is where the power,volume, source select bar is connected and also the standby light and the remote sensor.

I tested the pins with my multimeter and they read like this

pwr= reads 3.3
sensor = its not in use
key = reads 3.3
3.3v = reads 3.3v the other labeled 3.3v its not in use
IR = 3.2
LED_B = reads 0v no volts
LED_R = its not in use

I did a little test i Measured the voltage on PWR and when i press the power button it goes from 3.3 to 0v is that normal?

if you guys need more pics please tell me thankyou all for your help.

[tom66]

Re: AOC Envision LE24H067 Wont turn on at all

Try pressing the buttons on the board; does the KEY voltage vary?

[PlainBill]

Re: AOC Envision LE24H067 Wont turn on at all

Hello thanks for your time. Well i did the test with the main board connected and i still dont get any voltage reading from Pin 1 of CN902.
I also tested the tv connecting a dvd player and i couldnt hear anything.

Does this all mean I have a bad video logic board?
is there a way i can fix it?


What is my next step please?

The approach that is most likely to succeed is to replace the main board. There is a white label with a bar code on it, the top line is partially obscured, it most likely is the part number of the board. Google that number.

PlainBill

[kaks]

Re: AOC Envision LE24H067 Wont turn on at all

Ok i tested the voltage on the KEY pin as TOM said and YES the voltage varies when i press the volume, channel, menu and source buttons BUT Voltage does not varie when i press the Power key. is this OK?

[tom66]

Re: AOC Envision LE24H067 Wont turn on at all

Ok i tested the voltage on the KEY pin as TOM said and YES the voltage varies when i press the volume, channel, menu and source buttons BUT Voltage does not varie when i press the Power key. is this OK?

Does the PWR voltage change when the power button is pressed?

[tom66]

Re: AOC Envision LE24H067 Wont turn on at all

The approach that is most likely to succeed is to replace the main board. There is a white label with a bar code on it, the top line is partially obscured, it most likely is the part number of the board. Google that number.

PlainBill

This is a good approach, but a main board can be expensive. It would be good to see if it can be repaired first.

[kaks]

Re: AOC Envision LE24H067 Wont turn on at all

No the voltage does not change i know there is voltage on the pwr it reads 3.2v
so what should be my first step to test the main video logic board? thank you

[tom66]

Re: AOC Envision LE24H067 Wont turn on at all

No the voltage does not change i know there is voltage on the pwr it reads 3.2v
so what should be my first step to test the main video logic board? thank you

First I would like you to post a picture of the switch board; both sides. It's possible the button is faulty. I have seen cases where the power button is stuck down which holds the TV in a standby mode or permanently turns it off. Or maybe the button controls the standby.

If that proves fruitless then the main board becomes the suspect.

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]

Re: AOC Envision LE24H067 Wont turn on at all

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.