Sharp LC40LE531E Red/Green flashing LED

[Nevillet]

Hi,

I have the above TV which will not turn on. I understand the flash code is pointing to a faulty inverter board:



The main connector on the bottom connector has the following readings when the LED is blinking Red/Green (from left to right)

1. 24v
2. 24v
3. 24v
4. 24v
5. N/C
6. GND
7. GND
8. GND
9. N/C
10. N/C
11. N/C
12. 0.013v
13. 3.3v
14. N/C

any ideas where to start?

Thanks in advance.

[dick_barton]

Do you have 24V on each side of the fuse F1?

[Diah]

your reading of the voltage on CN1 look not correct with pins NO
you have pins 1-5 24V and from 6-10 GND , pin 11 are error out you wrote N/C

second read the voltage on CN3 between VCC Pin1(red probe ) and led 1 & 2, same to the next VCC pin5 and led 3 & 4

[Nevillet]

Fuse F1 is good.

I have rechecked what I listed for CN1 and i'm correct with the population of pins in the connector.

With CN3, the connector to the LED strings I think I measured as you requested.
As you look at the connector, with arrow on the right I used that as my + red reference That is pin1.

1. VCC (+reference)
2. LED1 10.50V
3. LED2 10.56V
4. NC
5. VCC 0.0V
6. LED3 10.58V
7. LED4 10.55

..and the 2 electrolytics are fine ESR/capacitance wise

[Diah]

Originally Posted by Nevillet

Fuse F1 is good.

I have rechecked what I listed for CN1 and i'm correct with the population of pins in the connector.

With CN3, the connector to the LED strings I think I measured as you requested.
As you look at the connector, with arrow on the right I used that as my + red reference That is pin1.

1. VCC (+reference)
2. LED1 10.50V
3. LED2 10.56V
4. NC
5. VCC 0.0V
6. LED3 10.58V
7. LED4 10.55

..and the 2 electrolytics are fine ESR/capacitance wise

CN3 pin 5 VCC , you need to use it as references to measure led 3 &4.
i forget to mention this test of CN3 you need to put the probe on the test point then plug the set in wall socket to remark the high and low reading at each pins.

i dont think the issue at inverter.. you have CN2 which i think its connected to the T-CON correct ?

[budm]

12. 0.013v
Pin 12 is ENA (BL-ON pin), <1V = Backlights OFF, > 2 ~ 2.5V = Backlights on
TV is off, Put black probe on the chassis, red probe on PIN 12 (ENA = BL-ON), turn on the TV while watching the meter to see if it jumps up over 2VDC or not.

[Nevillet]

If I measure CN3 pin 5 VCC to pin 6 and pin 7 I read the same 10.5v
This measurement is taken when the front LED is blinking red/green.

If i disconnect the TV from the wall supply - then reconnect, the front LED goes solid red.
If I measure CN3 in this state these are the readings:

1. VCC
2. LED1 (pin1 to pin2 = 1.75v)
3. LED2 (pin1 to pin3 = 1.76v)
4. NC
5. VCC
6. LED3 (pin5 to pin6 = 1.8v)
7. LED4 (pin5 to pin7 = 1.68v)

CN2 Connects to the T-Con board.

Measuring CN1 pin12 with reference to ground:
In standby 0.413v
In 'on' 0.013v (using a Fluke 187 it does not appear to jump over 2v)

[dick_barton]

.

[Nevillet]

Hi Dick,

I can't read any text in your 1:43 #8 posting.

[dick_barton]

Sorry. I initially replied with a comment but then noticed after posting that I had made a mistake. Once posted there is no way to delete the posting other than to blank it.

[Nevillet]

Understood. Many thanks.

[Diah]

Originally Posted by Nevillet

If I measure CN3 pin 5 VCC to pin 6 and pin 7 I read the same 10.5v
This measurement is taken when the front LED is blinking red/green.

If i disconnect the TV from the wall supply - then reconnect, the front LED goes solid red.
If I measure CN3 in this state these are the readings:

1. VCC
2. LED1 (pin1 to pin2 = 1.75v)
3. LED2 (pin1 to pin3 = 1.76v)
4. NC
5. VCC
6. LED3 (pin5 to pin6 = 1.8v)
7. LED4 (pin5 to pin7 = 1.68v)

CN2 Connects to the T-Con board.

Measuring CN1 pin12 with reference to ground:
In standby 0.413v
In 'on' 0.013v (using a Fluke 187 it does not appear to jump over 2v)

then do both test you mentioned again but you need to turn on the set with RC at time the front LED goes solid red

[Nevillet]

Hi,

The TV is face down on the bench and to disconnect from the AC outlet I have been pulling out the Live+Neutral connection from the power board.

I have not been using the remote control, rather the push buttons on the lower edge of the TV bezel to take it out of standby.

Is this not achieving the same results?

[Diah]

yes of course its same.. so mean all the voltage you posted at your POST#7 after you press power on the side panel of the tv...?

[Nevillet]

I remeasured everything. It looks like there is a problem with the Pin 6 measurement. The connector to the LED strings was connected during these readings.

Standby
Pin-1 VCC
Pin-2 V between P1 & P2 0.884v
Pin-3 V between P1 & P3 0.836v
Pin-4 No Connection
Pin-5 V between P7 & P5 0.543v
Pin-6 V between P7 & P6 0.010v
Pin-7 VCC


On
Pin-1 VCC
Pin-2 V between P1 & P2 10.55v
Pin-3 V between P1 & P3 10.24v
Pin-4 No Connection
Pin-5 V between P7 & P5 10.02v
Pin-6 V between P7 & P6 0.020v
Pin-7 VCC

[Diah]

Originally Posted by Nevillet

I remeasured everything. It looks like there is a problem with the Pin 6 measurement. The connector to the LED strings was connected during these readings.

Standby
Pin-1 VCC
Pin-2 V between P1 & P2 0.884v
Pin-3 V between P1 & P3 0.836v
Pin-4 No Connection
Pin-5 V between P7 & P5 0.543v
Pin-6 V between P7 & P6 0.010v
Pin-7 VCC


On
Pin-1 VCC
Pin-2 V between P1 & P2 10.55v
Pin-3 V between P1 & P3 10.24v
Pin-4 No Connection
Pin-5 V between P7 & P5 10.02v
Pin-6 V between P7 & P6 0.020v
Pin-7 VCC

are there typo ??
the one i remark it with red color ... you mean between pin7 LED 4 and Pin 5 VCC correct?

[Diah]

as end.. CN3, seem the first group blue pin1 to white & black okay

the second group blue pin 5 to white okay.. and to black pin 7 had open LED

[Nevillet]

No there is no typo. The voltage on P6-P7 is low in both states.

[Nevillet]

Sorry, Sorry.
Crazy mistake on my part.
Pin7 is not VCC for LED 3 & 4.
Pin5 is VCC for pins 6 & 7

I will recheck all tomorrow when I'm not so tired.

Sincere thanks for your help

[budm]

https://www.badcaps.net/forum/attach...0&d=1610474573

What DC Voltage do you get on U3 Middle pin (big tab) with ref. to the negative leg one of 220uf 35V cap (the two caps are connected in parallel so you can use any one of the two caps)?