Sharp aquos LC-40LE810E

[Jstone86]

Re: Sharp aquos LC-40LE810E

Since you do have 3.25V PNL-POW control signal, so do you get 12V at the PNL-12V connector pin?

Finally I was able to located PNL-12V. I got 2 volts when I Power on the TV and it immediately drop to 0

[Davi.p]

Re: Sharp aquos LC-40LE810E

Hi, i have the same TV with same problems as Jstone, apart the fact that i have not put any new resistor, i have changed the PC7703 opto with a good one and now i have good AC-DET signal, then i've changed the rest of the 3 opto with no changement, i have from seconds by the power-on and for some seconds a tension of appr. 7V on PNL-12V then it decreases to 0 slowly. Now i will study the PANEL SUPPLY that is probably a separate supply stage.

[Davi.p]

Re: Sharp aquos LC-40LE810E

The 13,2V output supply rail is regulated by the fixed linear regulator KIA378R12PI (Q7909) that outputs 12v normally, with an enable pin, as the d.sheet says the eanble pin (Vc) activates output when is >=2v, mine is 3v from the PNL_POW signal so i think the KIA doesn't work well.

[budm]

Re: Sharp aquos LC-40LE810E

'KIA378R12PI' That is the common failure Switched 12V LDO regulator IC.

[Davi.p]

Re: Sharp aquos LC-40LE810E

HI Budm, sorry, you are meaning the KIA is a common problem for theese tvs? I have ordered the part from Aliexpress. We will see between 1/2 months maybe.

[Davi.p]

Re: Sharp aquos LC-40LE810E

Damn! Some sad doubts comes... I have supplied externally 12v to the tcon leaving the PSU tcon supply connector disconnected, before i switch on the tv i switch on the ext. PSU, the voltage falls to the same 7V, when i switch on the tv suddenly tcon voltage become 12v but after some secs tv goes in protection with the same 2 flashes and tcon voltage falls to the 7V. I have done researches on tcon, none of the power semicon tests in short with tester current in, also tested one internal mosfet of a pmic. I'm sad...

[Jstone86]

Re: Sharp aquos LC-40LE810E

I noticed something today, if 8 removed the tcon connector pin power from psu board I get 12volts on PNL pin 1 & 2 2 which immediately drops to 0.but when I connected the tcon I get 2 volts on pnl pin 1 & 2 and drop as usual. By the way the I think there might be some problems with the tcon cuz I see some black mark on the tcon Pl female comector. Here is ten attach pics

[Davi.p]

Re: Sharp aquos LC-40LE810E

Too much pictures from me, e-ehm... that seems only a pencil mark..

[Jstone86]

Re: Sharp aquos LC-40LE810E

Too much pictures from me, e-ehm... that seems only a pencil mark..

Hehehe just wants to make sure that I ruled everything out

[budm]

Re: Sharp aquos LC-40LE810E

HI Budm, sorry, you are meaning the KIA is a common problem for theese tvs? I have ordered the part from Aliexpress. We will see between 1/2 months maybe.

Example:
https://www.badcaps.net/forum/showth...ht=KIA378R12PI
https://www.badcaps.net/forum/showth...ht=KIA378R12PI

[Jstone86]

Re: Sharp aquos LC-40LE810E

So budm just to clarify for my TV, I need to CHANGE the KIA378R12PI??

[budm]

Re: Sharp aquos LC-40LE810E

Disconnect the PL connector on the T-CON board then put the on the PNL12V pin on the power supply board then turn on the TV to see if the output will jump up to 12V or not, if not then more likely to be bad KIA.

[Jstone86]

Re: Sharp aquos LC-40LE810E

Disconnect the PL connector on the T-CON board then put the on the PNL12V pin on the power supply board then turn on the TV to see if the output will jump up to 12V or not, if not then more likely to be bad KIA.

I indeed get 12v when I disconnected the Pl connector. But only 2v flows in when I connected back the Pl. So that means my KIA378R12PI is OK right? What do u suspect the problem is

[Davi.p]

Re: Sharp aquos LC-40LE810E

You have to put a resistor or a 12v Lamp as load to the PL output so you can judge better if KIA is good or not. If it stays on then the tcon has problems.

[budm]

Re: Sharp aquos LC-40LE810E

OK, next test will be with dummy load, you can simulate 1A load by using 12 Ohms 10W resistor to see if it can handle 1A load or not.
If you are going to use the lamp, you need to check its cold resistance first since cold resistance will be about 15 times lower than the hot resistance.

[Davi.p]

Re: Sharp aquos LC-40LE810E

Hi Budm, warning: my test with external supply to tcon was faulty due to a defective crocodile test cable used, swapped it with a good one the tv is perfectly working so the problem is merely the only KIA chip that is faulty, BYE BYE to ALL.

[Jstone86]

Re: Sharp aquos LC-40LE810E

OK, next test will be with dummy load, you can simulate 1A load by using 12 Ohms 10W resistor to see if it can handle 1A load or not.
If you are going to use the lamp, you need to check its cold resistance first since cold resistance will be about 15 times lower than the hot resistance.

I think i can get 12R 10W resistor from the local electronic shop here but i have also ordered KIA378R12PI from aliexpress which delivery is approximately 2 weeks.by the way can you please show me how i can stimulate or test with the 12R 10W resistor.pictures wud be better .thanks

[Davi.p]

Re: Sharp aquos LC-40LE810E

I think this test is facoltative, i guess surely your KIA is bad, wait the piece and try it.. bye.

[Jstone86]

Re: Sharp aquos LC-40LE810E

After theKIA378R12PI (Q7909) arrived, I changed it and as usual TV dosent turn on. Previously I got 2v PL pin 1 and 2 when I turn on the TV but now get 0.67v so memu touch key buttons don't respond only TV remote also the led light blink 2-2 without stopping hmm. If I disconnected the Pl connector I get 12volts on PNL pin 1ansd 2

[budm]

Re: Sharp aquos LC-40LE810E

Next is to keep the DCV meter on the PL connector, remove the ribbon cables between the LCD panel and T-CON to see if the PL connector will jump up to 12VDC or not when TV is turned on.
BTW, did you do the test with the dummy load?