Sharp LC-40LE810UN question

[mattstolte]

Re: Sharp LC-40LE810UN question

anyone?

[rievax_60]

Re: Sharp LC-40LE810UN question

The back light began to flicker. I found opto PC7701 to be temperature sensitive.
It seems that the optos in these power supplies are from a dud batch. I suggest that all four of them need to be replaced. I left the resistor mod in place.
I have rarely seen optos fail for their own reasons.

[iuliantv]

Re: Sharp LC-40LE810UN question

Don't do shorting pins .Can you desolder that chip .Power up with removed eeprom chip.Tell what is the blinking code.What i think after a few unsuccess power ups (errors ) , firmware write code in this chip to prevent from further power on(may be for safety )

Hi everyone, I have a similar problem with a Sharp LC-40le810e, front LED flashes 2 times and break and flashing 2 times, and so, according to the service manual,, Flashes 2 times 2 Power supply error (* 2) UR + 13V error,, really I lack this tension, though I try to remove EPROM memory, but do not realize is this memory, all have a strange notation,, ic2004 (denoted by 402m 40b2) 5001 IC (24lc21ai) thank you

[iuliantv]

Re: Sharp LC-40LE810UN question

Hi everyone, I have a similar problem with a Sharp LC-40le810e, front LED flashes 2 times and break and flashing 2 times, and so, according to the service manual,, Flashes 2 times 2 Power supply error (* 2) UR + 13V error,, really I lack this tension, though I try to remove EPROM memory, but do not realize is this memory, all have a strange notation,, ic2004 (denoted by 402m 40b2) 5001 IC (24lc21ai) thank you

I took ic2004 (denoted by 402m 40b2) the same error, I think IC5001 (24lc21ai) has something to do with this error because it is located in the hdmi I tried starting the service mode with the following variants STBY and V-, STBY and V + and p + STBY, STBY and p- without result

[iuliantv]

Re: Sharp LC-40LE810UN question

no idea ?

[rievax_60]

Re: Sharp LC-40LE810UN question

It is difficult to follow your problem. Did you rule out the PC7703 opto?

[Krebstar]

Re: Sharp LC-40LE810UN question

Hello,

Some searching via google has led me to this thread. Not to post hijack, but there don't seem to be many threads about this set. I also have the LC-40LE810UN Tv. For a few months now the set will work just fine. Then, after 5 minutes or so the back light will begin to flicker ( much like an old neon tube). Its more of a sporadic flicker ( different intensities) then a steady pulsing.

It happens on every input regardless if it is receiving a video signal or not. When I go to turn the Tv off, the screen ( not the 'V') flashes 6 times slowly. I cannot find any information on this particular blinking. Most people with issues seem to have the 'V' blinking error codes. There isn't even a 6 blink code in the service manual ( that I saw).

Can anyone offer any suggestions? I'm fairly handy with electronics and such If I know where to look. Power issues? Over heating?

Also, can anyone translate the directions on how to enter the adjustment process mode ? What does "Before entering the adjustment process mode, the AV position RESET in the video adjustment menu" mean? Do I need to just highlight reset or do I need to actually reset the input? Kind of confusing. I was going to check the menu to see if any errors are listed.

Thanks for any help !

[rievax_60]

Re: Sharp LC-40LE810UN question

I found the instructions confusing also. I remember making sense of it, I don't fully remember the details now.
Most are developing a shutting down problem with 2 flashes of the standby LED. This is caused by optpo-coupler PC7703 in the AC_DET circuit gradually losing gain. My TV had this problem first. I fixed it by reducing the resistor on the its LED side.
The TV then developed a flickering problem a few months later. I found another failing opto in the back-light circuit. At this stage I decided to replace all 4 optos.

[Krebstar]

Re: Sharp LC-40LE810UN question

I found the instructions confusing also. I remember making sense of it, I don't fully remember the details now.
Most are developing a shutting down problem with 2 flashes of the standby LED. This is caused by optpo-coupler PC7703 in the AC_DET circuit gradually losing gain. My TV had this problem first. I fixed it by reducing the resistor on the its LED side.
The TV then developed a flickering problem a few months later. I found another failing opto in the back-light circuit. At this stage I decided to replace all 4 optos.

Thanks for your quick response. I plan on taking a look at the boards this weekend. Maybe Ill just replace to opto and go from there. Is there a schematic floating around somewhere? Thanks again !

[rievax_60]

Re: Sharp LC-40LE810UN question

The local TV repair guy says that the power supply schematic is often not included in TV service manuals as it isn't with this one.

[budm]

Re: Sharp LC-40LE810UN question

Power supply board is made by DELTA (DPS-126CP) so it is not allowing Sharp or other companies to release the diagrams.

[Krebstar]

Re: Sharp LC-40LE810UN question

Opened my tv up today to inspect things. I think Im just going to replace all the optos since they ( form what Ive read) seem to be the likely suspect. Does anyone have a source for these optos? My usual electronic suppliers don't seem to carry them. Is there a comparable alternative?

Cosmo
1010
817
K10
H

[Krebstar]

Re: Sharp LC-40LE810UN question

So after taking the back off, I have been running the tv for about 8 hrs now with no back light flicker. Could it be the set was over heating with the back on? I that would explain why it wouldn't flicker right away, but after 5-10 minutes or so. I noticed there are no vent holes above the power board on the back of the case. Why would they do that? Seems that component would be sensitive to heat.

[budm]

Re: Sharp LC-40LE810UN question

Opto is also sensitive to heat.

[rievax_60]

Re: Sharp LC-40LE810UN question

I noticed that the faulty optos were temperature sensitive. Symptoms became worse with increasing temperature. The 817 opto is manufactured by more than one manufacturer.
I pulled mine out of a junked plasma power supply.
There is a bothersome aspect to choosing new parts. There is a wide range in the Current Transfer Ratio spec for the various suffix codes. https://cdn.badcaps-static.com/pdfs/...7b665a5160.pdf
In most circuits the CTR doesn't matter much, so long as it's high enough. I noticed that the opto(PC7701) in the back-light circuit has a trim pot across the LED side. This can only be to adjust for the optos CTR. I would try to get the K817P3.

[Krebstar]

Re: Sharp LC-40LE810UN question

So what are your thoughts about cutting away the back case above those optos to improve air flow? Do you think it would be worth it? I mean the set is working great now. So much so Im debating even putting the case back on .

[rievax_60]

Re: Sharp LC-40LE810UN question

That is not a good idea. You could adjust the trim pot that is across the LED side of the opto. There are 2 pots. You will have to look at the print to see which is the correct one. Measure the resistance before you move it so you can put it back to the same setting later.

[rievax_60]

Re: Sharp LC-40LE810UN question

This is the data PDF for the Cosmo opto. Try to work out what the CTR spec is from the info in page 4.

[Krebstar]

Re: Sharp LC-40LE810UN question

That is not a good idea. You could adjust the trim pot that is across the LED side of the opto. There are 2 pots. You will have to look at the print to see which is the correct one. Measure the resistance before you move it so you can put it back to the same setting later.

Excuse my ignorance, but what does adjusting the pot actually do? Once I dial it in is it something I can leave alone? Why would I need to 'put it back to the same setting later'?

[rievax_60]

Re: Sharp LC-40LE810UN question

Excuse my ignorance, but what does adjusting the pot actually do? Once I dial it in is it something I can leave alone? Why would I need to 'put it back to the same setting later'?

Adjusting the pot might compensate for the reduction of CTR that the original optos seem to suffer from. This loss of CTR is what causes the AC-DET problem and the instability of the back-light power control loop.
It is always a good idea to note the original position of things before they are moved. In this case it might be decided to put the pot back to the original position after the opto is replaced.