Sharp aquos LC-40LE810E

[budm]

Re: Sharp aquos LC-40LE810E

I will explain to you later as to why the VDC measured between pin 3 and pin 4 of the opto goes down when you add 68K resistor on the LED drive side. If you look at my picture on post 70 you will understand why.

[budm]

Re: Sharp aquos LC-40LE810E

What DCV do you have between the two VCC pins as I marked?

[Nightmare0]

Re: Sharp aquos LC-40LE810E

I put it on R7019
In that post he is saying R2019 but its typo. If you check photo he really soldered it to R7019
Please check that photo I added in post 63, if I am measuring in correct way.
Leg 3 of PC7703 with 68k resistor soldered on top of existing resistor according my photo to gnd I got 1.68v

[rievax_60]

Re: Sharp aquos LC-40LE810E

So you now have 2v on pin 3 to ground? same as before? It should have made a large difference.
Where did you put the 68k? Look at post 279, https://www.badcaps.net/forum/showth...AC-DET&page=14

[Nightmare0]

Re: Sharp aquos LC-40LE810E

Leg 3 to gnd is showing 1.68V. Tomorrow i will buy 10 more optos and change all of them again

[Nightmare0]

Re: Sharp aquos LC-40LE810E

I just added 68k resistor. I forgot to take a photo. Now between 3 and 4 opto leg I am getting 3,06V
Tv didn't started. On AC-DET pin 9 I am still not getting any voltage.

[rievax_60]

Re: Sharp aquos LC-40LE810E

If pin 3 doesnt go over 3 volts after the 68k is added, then replace PC7703. BTW opto couplers dont like being heated for too long.

[rievax_60]

Re: Sharp aquos LC-40LE810E

Is that after you added the 68K?. You didnt say. At 2.5v on pin 3 of PC7703, you might see some voltage on the AC-DET but the TV will not start unless AC-DET is solid high level, no pulses.

[Nightmare0]

Re: Sharp aquos LC-40LE810E

On opto there is:
Cosmo
1010
817
K20

These are original. I measured pins between 1 - 2 and 3 - 4 like in this photo. Is it correct? I found pin numbers like that on google.

[Nightmare0]

Re: Sharp aquos LC-40LE810E

Sorry I confused you. First time that trick was working I used 570ohm resistor. I just plugged resistor next to pin 11 and other end of resistor to pin 9. I never tried that without resistor. Just after opto change that resistor trick didn't worked again. Same as I put original optos back.

That voltages from pin 3 and 4 I got to GND. Voltage of PC7703 between pin 1 and 2 is 0,99V and between 3 and 4 is 2,56V (this voltage goes to 0,08v after tv starts to show error code)

[budm]

Re: Sharp aquos LC-40LE810E

"Tried that magic trick with resistor again, but this time tv didn't turned on. Not even led. Just red led on mainboard. " I am a little bit confused here, the first time you did not use any resistor between the AC-DET wire ("I took out pin 9 - AC-DET an just plugged it next to pin 11 - 5v. Without any soldering") and the STBY5V, you had it connected directly without the resistor, and now you are using the 330~1K resistor between the 5V and the AC-DET but the TV will not work this time, is that correct?
BTW, what is the P/N of that opto for the AC-DET?
What DCV do you get between pin 1 and pin 2 (the LED side), and between pin 3 and pin 4 (the photo-transistor side)? Notes: The measurement is for between the legs, not with ref to the circuit GND.

[rievax_60]

Re: Sharp aquos LC-40LE810E

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

[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

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.

[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

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

[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

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

[rievax_60]

Re: Sharp aquos LC-40LE810E

The opto for the AC-DET is PC7703

[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.