Sharp LC-90LE745U 3 slow and 1 fast Blink

[c00lman]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Deleted, duplicate post

[nicholas1110]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Hello, it sounds like you need to go into service mode and clear the backlight error count. Doing the force turn on does not clear anything it is just for testing for troubleshooting. Once the error count is clear you should not get the 1-1 blink (unless there is still a led issue) any longer.

[c00lman]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Hello, it sounds like you need to go into service mode and clear the backlight error count. Doing the force turn on does not clear anything it is just for testing for troubleshooting. Once the error count is clear you should not get the 1-1 blink (unless there is still a led issue) any longer.

Yeah unfortunately pressing the input and volume down. The tv flash and the backlight flicker and then back to 1-1 blinks

[RDC55]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Do you have an LED tester? It appears the TV is a full array backlit version with nothing about local dimming that I could find. When looking at the LED voltages that you posted a couple are suspicious, which I think warrants checking each individual string.

And just to add it was stated earlier that STB was standby, but you can find other info posted about Sharp TV's indicating that is the actual BL_ON command.

How old is the TV?

[c00lman]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Do you have an LED tester? It appears the TV is a full array backlit version with nothing about local dimming that I could find. When looking at the LED voltages that you posted a couple are suspicious, which I think warrants checking each individual string.

And just to add it was stated earlier that STB was standby, but you can find other info posted about Sharp TV's indicating that is the actual BL_ON command.

How old is the TV?

The TV is around 7-8 years old.

I dont have a back light tester, i can check and see if they are not that expensive that I can purchase. To test the back light strip, do we need to remove the panel/screen or can we do it just on the wire connector?

coz I've seen videos of repairing the strip but that involved removing the screen panel itself and that thing is delicate hahahd and removing a 90 inches screen is not going to be fun hahahah

I'm just checking the power supply board to see if there's any shorts if not, then we'll decide if we still going to have it repaired or for parts.

[RDC55]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

You can purchase a backlight tester fairly cheap, in the area of $20 USA.

No need to remove the screen to test the backlights. You can do it from the connectors that mate with the power supply.

And yes, removing that panel is probably the last thing you want to do, so a thorough diagnosis needs to be done first.

I was curious also, is the heartbeat indicator flashing every 2 seconds or so with the new board?

It is also an interesting thought about where the backlight fail count is stored. Say for example if it was stored on the Main board and the board you received has exceeded the 4 count and needs to be reset, or is it stored on the Power Supply and reported to the Main?

[c00lman]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

To test the backlight, I'm assuming I will connect the backlight tester to the LED 1-A and LED 1-K which will be the + and - for the LED Strip? the power supply has 2 Connectors going to the LED strips. L1 connector is marked LED1-A, LED2-A, etc then L2 connector is marked LED1-K, LED2-k. once connected, I have to see if the backlight LED strip will light up right? through the small holes in the chassis? the test I'm going to do is to see if all strip will light up and not the individual LED lights right?

When we initially installed the main board, the heartbeat blinks once during the power and the tv tried to turn on the shutdown after with the 1-1 blinks. Tried few times then it went to the 1-1 immediately. So the count might have reach 5. But can’t reset it as can’t go to the service menu I think it's storing the Code on the main board as the power supply does not power on/click anymore when it's doing the 1-1. the Main board might not be sending the PN-ON and PN-POW signal to the Power Supply to turn it on.

For the heartbeat, if the TV is on the blinking 1-1 state, the main board does not blink anymore. But if we force boot or try to go to Service menu. Then it’s flashes.

Ordered a back light tester and will test and update.

again, thank you very much for all the assistance and knowledge

[RDC55]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

To test the backlight, I'm assuming I will connect the backlight tester to the LED 1-A and LED 1-K which will be the + and - for the LED Strip? the power supply has 2 Connectors going to the LED strips. L1 connector is marked LED1-A, LED2-A, etc then L2 connector is marked LED1-K, LED2-k. once connected, I have to see if the backlight LED strip will light up right? through the small holes in the chassis? the test I'm going to do is to see if all strip will light up and not the individual LED lights right?

Yes, you will be checking the strips as you suggested above and not the individual LED's. However, when the LED tester is used on the strips the displayed voltage should be virtually identical for all the strips, which in essence verifies each LED is producing the correct Vf.

I have done some searching on replacement strips and haven't seen anything. It is nice to know what to expect and if you know the number of LED's per strip then it is easy to make an initial estimate.

[c00lman]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Yes, you will be checking the strips as you suggested above and not the individual LED's. However, when the LED tester is used on the strips the displayed voltage should be virtually identical for all the strips, which in essence verifies each LED is producing the correct Vf.

I have done some searching on replacement strips and haven't seen anything. It is nice to know what to expect and if you know the number of LED's per strip then it is easy to make an initial estimate.

Thank you. So if I understand it, when testing using the backlight tester to test the strips. They should all have the same/similar voltage. If a strip is showing more voltage (or less) then we can assume the strip is bad?

Hopefully we don't need to go that far.. removing that panel will be a pain LOL as just the TV itself is heavy and removing the panel at the same time trying to not to break LOL hahahah

[c00lman]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Got the backlight tester and tested all 16 strips.

They all light up and the voltage display is showing 197/198Volts.

[mmartell]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

That doesn't sound right even for a screen of that size does it ? Almost 1000 3v leds or even 500 at 6v ? I could be wrong of course...

Also some edge lit sets have leds at the top and sides and since they're different lengths the strings will have different forward voltages.

Would be good to see an internet pic of one of these with the screen removed.

[c00lman]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

can't find a pic of this size with the screen removed LOL

to use the back light tester, i just put the positive on the LED1_A Pin then the black negative to the LED1_K pin. and when the LED light up, I noted the voltage on the tester. I'm assuming it's giving 197/198V on that one strip? then proceeded to LED2_A and LED2_K and so on up to LED16. all are showing 197/198V. if one strip is showing a different voltage then at least it should show that strip is defective. can we assume the backlight strips are ok? or maybe they are all bad LOL that's why it's showing all the same hahaha

oh dont touch the lead at the same time.....

[RDC55]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

I had thought about different strips and sizes that might cause a difference in Vf, but was hoping you would find an obvious issue like an open strip. The fact that they all appear the same my first thought is there is not an issue with the individual strips.

And just to ask what LED tester did you purchase? Most of the more inexpensive ones do not supply much current so on rare occasions they can give a false indication of the strips.

As for the number of LED's here is a link to an 80 inch backlit Sharp, and by my count there are 450 LED's (who would of thought that many?) so it is not a stretch to imagine the 90 inch having 500+ LED's.

http://www.tvpartscentral.com/sharp-...e632u-led-set/

The other question is why were the measured LED voltages so different when the forced on was done and the voltages measured? I can't find anything that says this TV has local area dimming, but that doesn't mean it can't individually control the LED strips to conserve energy. Perhaps others can weigh in on that? Perhaps we need to consider how to force the Power Supply backlight on to measure the strips to get a better evaluation of the Power Supply / LED strip. Budwich suggested something similar to this earlier but didn't provide details on how to enable the backlights - my guess is the STB pin but for now that's is just a guess so I don't want to direct the OP in that direction.

[c00lman]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

I will measure the voltage again when force boot.

The initial measurement I did is from gnd to the pins. Not from the pins + and -

Let you know

[budwich]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

As indicated, backlight testers are a "gross tool" for "quickly testing" backlights. However, most cannot provide the current demands that are used. Hence, if you have individual led issues, these may not be detected other than the system in the set that monitors the amount of current being used. Jumping the power board to turn it on should also turn on the backlights in most cases assuming that you have disconnected the main board (ie. you can't jump the pins and leave the cable connected). Your previous posted voltages seemed to indicate some difference therein.

edit: the OFL (pin 23) might need to be set.... but this is just a guess. there are posts in the forum for forcing backlights on somewhere.

[c00lman]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

I will Try to redo the measurements lol. This time. I will put the plus to the L1 connector and negative on the L2 connector with corresponding pins.

I’m also thinking of measuring the current on each LED strip by putting the multimeter in series and hopefully will get different readings. I am assuming if there’s any shorts on the individual LED, the current consumption should go up a bit. I’m also assuming the LEDs are in series. Unless my theory is flawed lol hahaha

[c00lman]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Tried to jump the power supply (bu5 and ps-on or bu5 and ps-on and pn-pow). But it does not activate or turn on the back light . The only way I can turn on the back light is via the force boot ch- and vol +.

Measuring from ground to led-k. L2 connectors
All pins are around 112 to 114 v.

From Leda and led k.
All pins are around 139 to 140v


Measuring the current on each strip (disconnecting it from the connector and putting the multi tester in series) I’m getting

Led1. 18.4 ma
Led2 18.3 ma
Led3 18.4ma
Led4 18.1ma to 18.3
Led5 18.3ma
Led6 17.9 - 18.2
Led7 17.9 -18.2
Led8 17.8
Led9 17.7 to 18
Led10 17.9 18.1
Led11 18.1
Led12 18.0
Led13 18.0 18.1. Sometimes to 19
Led14 17.7
Led15 17.9
Led16 17.8

Some of the led strips current is steady and some are ranging within .1 to .3 mA difference except for led13. It’s fluctuating sometimes up to 19mA. Not sure if it’s the connection or it does not really measure to anything hehehe

I will try to do some more measurements within the next days. It’s really hot �� lol

I think this one is beyond my electronics skills. Wish we have some schematics on this power supply or Sharp created the TV that you can check/replace the LED without dismantling this gigantic screen lol

Again, DO NOT touch both metal leads when measuring haha not fun
Let me know what you think

[RDC55]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

My first thought is that would have been one hundred and something mA's, but not that important right now. I would add that the similarity between all of them suggest there is not a problem with the strips.

I pieced together a 60 inch just to see what state "error" is when safe. From what I have read on this site and the test I did error is low when safe, you do have a high but the logic doesn't necessarily have to follow the smaller sets.

On the 60 inch, which is quite a bit different the STB pin must be high for the backlights to come on at full current. The PWM signals will put the backlights in a soft start condition with STB low, but when STB goes high PWM signal goes from high to active adjusting the brightness. I guess the point here is that to force the backlights STB would need to be held high, but the dilemma then comes with what to do with SDA, SCL, and VCLK - just opening this thought for discussion.

Perhaps the LED controller has a datasheet, so maybe post a clear pic of the backside of the Power Supply and see if you can get the numbers off that IC, which is IC7201 an 80 pin IC. It might be a dead end if no datasheet exists, which is fairly common.

I suspect you have done it right but just to be sure when trying to enter the service menu you are starting with the TV unplugged and following the steps below:

Entering the adjustment process mode
1)Press and continue to hold the VOL v & INPUT buttons while plugging in AC power.
2)Continue to hold the VOL v & INPUT buttons until <K> appears on the top left side of the Display


Have you tried the reset with the latest board?

[c00lman]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Thank you for the reply, yeah.. I was hoping for a huge voltage or current difference on the strip to indicate it's a strip issue but they are almost identical

I will take a pic of the back of the power supply board.

That is the procedure I'm following, pressing the Input and Volume down while plugging the AC power, the main board LED will blink, then after few seconds, I will hear the power Hum indicating it's activating the backlight, then the back light will flicker then power supply shutdown and the indication is doing the 1-1.

Also, using the laser temperature measurements, the power supply board seems to be warming up. not sure if it's because of the heatsink of the LED strip Regulators but it seems that the board is hotter than the heatsink lol

My first thought is that would have been one hundred and something mA's, but not that important right now. I would add that the similarity between all of them suggest there is not a problem with the strips.

I pieced together a 60 inch just to see what state "error" is when safe. From what I have read on this site and the test I did error is low when safe, you do have a high but the logic doesn't necessarily have to follow the smaller sets.

On the 60 inch, which is quite a bit different the STB pin must be high for the backlights to come on at full current. The PWM signals will put the backlights in a soft start condition with STB low, but when STB goes high PWM signal goes from high to active adjusting the brightness. I guess the point here is that to force the backlights STB would need to be held high, but the dilemma then comes with what to do with SDA, SCL, and VCLK - just opening this thought for discussion.

Perhaps the LED controller has a datasheet, so maybe post a clear pic of the backside of the Power Supply and see if you can get the numbers off that IC, which is IC7201 an 80 pin IC. It might be a dead end if no datasheet exists, which is fairly common.

I suspect you have done it right but just to be sure when trying to enter the service menu you are starting with the TV unplugged and following the steps below:

Entering the adjustment process mode
1)Press and continue to hold the VOL v & INPUT buttons while plugging in AC power.
2)Continue to hold the VOL v & INPUT buttons until <K> appears on the top left side of the Display


Have you tried the reset with the latest board?

[RDC55]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

"That is the procedure I'm following, pressing the Input and Volume down while plugging the AC power, the main board LED will blink, then after few seconds, I will hear the power Hum indicating it's activating the backlight, then the back light will flicker then power supply shutdown and the indication is doing the 1-1."

And you have continued to hold the volume v and input for a good 20 to 30 seconds after plugging in the set, just in case the main has to boot to a point to recognize the command.