Sharp aquos LC-40LE810E

[Nightmare0]

Re: Sharp aquos LC-40LE810E

Wow. You guys are awesome ! Real professionals.
I took out pin 9 - AC-DET an just plugged it next to pin 11 - 5v. Without any soldering. It's just touching and TV has started up. Everything seems to be working.
I will test it tomorrow. If you want, I can make some measurements for you. Is there anything that I should check before soldering it? I will also keep that 68k resistor and optos for future.

/edit
I added quick photos I will post more, when You allow me to solder that.

[rievax_60]

Re: Sharp aquos LC-40LE810E

If you do not restore proper function of the AC-DET, you will risk EEPROM corruption. Your TV will have similar function to that of a brick.

[budm]

Re: Sharp aquos LC-40LE810E

Glad to hear, so now we know that it is the AC-DET failure only, so it is either the resistor for the circuit is marginal or changed in value (goes higher resistance), or bad opto per suggestion by other members.
The purpose of the AC-DET is not to allow the TV to come on if the AC Voltage feeding the TV is too low, so right now it is the protection circuit is causing the fault due to its own failure.

[rievax_60]

Re: Sharp aquos LC-40LE810E

The function of the AC-DET is also to warn the controller of imminent loss of supply rails so that it wont risk writing to memory resulting in corruption.

[Nightmare0]

Re: Sharp aquos LC-40LE810E

I was celebrating too soon.

I changed all optos. Measured all pins...getting same voltage on all pins like before. Tried that magic trick with resistor again, but this time tv didn't turned on. Not even led. Just red led on mainboard.
I put all original optos back. Same... Red led on mainboard. When start without that resistor trick, tv is still flashing with same error.code. getting same voltages. Just resistor trick doesn't work anymore.
Could I burn optos? Or I really screwed something? I will send you photos tomorrow, I am sad and tired, so I am going to sleep now. But there weren't any cold joints, bridges, used flux, everything seemed nice.

[rievax_60]

Re: Sharp aquos LC-40LE810E

The first thing to check is that the optos are fitted the correct way. They dont all face the same way. Take a clear photo of the top before you do anything else.

[fzabkar]

Re: Sharp aquos LC-40LE810E

"I took out pin 9 - AC-DET an just plugged it next to pin 11 - 5v. Without any soldering. It's just touching and TV has started up. Everything seems to be working."

The AC-DET signal is normally tied to the supply via a pullup resistor. By connecting pin 9 directly to the BU5V supply pin, you would have impressed the supply voltage directly onto an MCU GPIO pin. This is not always a safe thing to do.

Edit: IC2002 is powered from BU+3.3V, so impressing BU5V onto its AC_DET pin would have resulted in latchup without any current limiting. I could be wrong, though.

[Nightmare0]

Re: Sharp aquos LC-40LE810E

Here are photos, after I changed all optos. I noticed they are not same brand. 2 of them were sharp and 2 of them different. Also I checked if I am fitting them in correct way. There is sign 1 on motherboard for dot in left top corner. Also there are marks on side and motherboard like half circle. So I am sure I fitted them correctly.

[Nightmare0]

Re: Sharp aquos LC-40LE810E

Here are photos after I put all original optos back. You can check, they are in same position. I added photo from shopjimmy so you can check they are really in proper way. Also photo of that red led. Red led is not still on. It is flashing like: maybe 20 seconds on, off for few seconds afaing 20 seconds..... after few flashes, led will turn off and nothing else happens.
I was not using TV with this fix. I tried that once, when I first tried for maybe 30 seconds until I took photo.
After opto change, it started to act like that. So how bad is it? All pins have same voltage. If you need more info just let me know.

[rievax_60]

Re: Sharp aquos LC-40LE810E

(PD-1-2)UR13.2V(SIGNAL): 12.9V
(PD-3-4)S13V.2(AUDIO): 12.9V (its not misspelled, its written like this)
(PD-5-6)SGND(AUDIO): 0V
(PD-7-8)SGND(SIGNAL): 0V
(PD-9)AC-DET: 0V
(PD-10)PS-ON: 3V
(PD-11)BU5V: 4.9V
(PD-12)PNL-POW: 0V

What are these voltages now? Keep in mind that some of these voltages might not stay up for long after the mains is applied.
I think AC-DET can only be high when PS-ON is high. It has been a few months since I worked on s similar model here.

[Nightmare0]

Re: Sharp aquos LC-40LE810E

(PD-1-2)UR13.2V(SIGNAL): 13.01V
(PD-3-4)S13V.2(AUDIO): 13.01V
(PD-5-6)SGND(AUDIO): 0V
(PD-7-8)SGND(SIGNAL): 0V
(PD-9)AC-DET: 0V
(PD-10)PS-ON: 3V
(PD-11)BU5V: 4.99V
(PD-12)PNL-POW: 0V

I am getting these voltages only when I plug tv to power. Because after while, tv will show error code and only 5v is present. Should I try that resistor on top of that second resistor?

[rievax_60]

Re: Sharp aquos LC-40LE810E

(PD-1-2)UR13.2V(SIGNAL): 13.01V
(PD-3-4)S13V.2(AUDIO): 13.01V
(PD-5-6)SGND(AUDIO): 0V
(PD-7-8)SGND(SIGNAL): 0V
(PD-9)AC-DET: 0V
(PD-10)PS-ON: 3V
(PD-11)BU5V: 4.99V
(PD-12)PNL-POW: 0V

I am getting these voltages only when I plug tv to power. Because after while, tv will show error code and only 5v is present. Should I try that resistor on top of that second resistor?

Yes, try that. We need to see AC_DET go high, Also measure the voltage on both pins on the middle opto on the secondary side, the side that is closer to the power supply output. Normally they should be 5v and something a bit lower than 5v.
Although it seems that you have another fault also.

[rievax_60]

Re: Sharp aquos LC-40LE810E

The opto for the AC-DET is PC7703

[rievax_60]

Re: Sharp aquos LC-40LE810E

I made a mistake before. PC7703 is the lower one.

[Nightmare0]

Re: Sharp aquos LC-40LE810E

Ok, i will do that as soon I will get from work.
I don't know how these optos work. Which legs should I measure? I will post results of all optos, so you can check that.

[rievax_60]

Re: Sharp aquos LC-40LE810E

You can do a search on the part number or "opto coupler". Measure pins 3 and 4 of PC7703.

[fzabkar]

Re: Sharp aquos LC-40LE810E

If the "resistor trick" doesn't work anymore, then I can't see how modifying the sensitivity of the optocoupler will change anything. ISTM that there is now a problem on the main board.

I would check whether AC_DET is shorted to ground on the main board.

[rievax_60]

Re: Sharp aquos LC-40LE810E

If the "resistor trick" doesn't work anymore, then I can't see how modifying the sensitivity of the optocoupler will change anything. ISTM that there is now a problem on the main board.

I would check whether AC_DET is shorted to ground on the main board.

Yes, that is a good idea. I keep thinking about damage on the main board also. I dont understand why there should be damage because he used a series resistor.

[Nightmare0]

Re: Sharp aquos LC-40LE810E

PC7703 legs 3 -2.1V and 4 -4,9V
Should I solder that 68k resistor on top of other now?

[rievax_60]

Re: Sharp aquos LC-40LE810E

Yes, solder in the resistor. pin 3 on the opto needs to be well over 2.5v.