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Old 06-21-2021, 05:18 PM   #1
c00lman
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Default Sharp LC-90LE745U 3 slow and 1 fast Blink

hi, new member her and apologize if this has been discussed.. tried to search and most of the result are for LC-xxLe6xx series and not sure if it's applicable to the 745U.

the TV stopped turning on and after the V logo stayed solid for a minute or 2, it gives the 3 slow and 1 fast blinks which from what I researched are internal communication error.

did some voltage measurement on the power supply out.
Pin 1 and 2 = 0V --> PNL 12V
Pin 3 and 4 = 0 V --> GND
Pin 5 to 8 = 13V --> UR 13V
Pin 9 to 12 = 0 V --> GND
PIN 13 = 3.24 V --> AC_DET
Pin 14 = 3.01V --> PS_ON
Pin 15 = 5.04V --> BU5V
Pin 16 = 0V --> PNL_POW
Pin 17 to 21 = 0V
Pin 22 = 3.24 = ERROR
Pin 23 = 0V
Pin 24 = 0V

from what I read on the other thread on this forum, the power supply will not turn on the PNL12V if there's no power on PNL_POW pin (correct?)

I measured the voltages on the big caps and they are 164V then jumps to 300++V.

Also the power supply clicks when plugged in.

thinking it's the main board as there's no PNL_POW, ordered it last week and just arrived today. plugged the replacement main board and no changes on the symptoms, plugged in and after few minutes, it does the 3-1 Blink.

both main board does not blink either (The LED on the main board).

What other test can I do to isolate if it's power supply or if the main board that arrived is bad. I understand that the TV is few years old and we will not be able to order new boards.

or is it time to say goodbye to it?

Attached are some pics of the the power supply

please and thank you in advance.
Attached Images
File Type: jpg 2021-06-21 15.27.54.jpg (73.3 KB, 12 views)
File Type: jpg 2021-06-21 15.27.58.jpg (65.6 KB, 10 views)
File Type: jpg 2021-06-21 16.35.46.jpg (86.4 KB, 21 views)
File Type: jpg 2021-06-21 16.35.49.jpg (82.4 KB, 8 views)
File Type: jpg 2021-06-21 16.35.53.jpg (80.6 KB, 9 views)
File Type: jpg 2021-06-21 16.35.58.jpg (141.9 KB, 14 views)
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Old 06-22-2021, 12:33 PM   #2
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Default Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Have you tried the reset?

Hold Vol+ and Ch- while plugging it in?

Curious about the SB pin #24 also, was that low with both Main boards?
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Old 06-23-2021, 11:40 AM   #3
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Default Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

From reads herein, I think that you can disconnect the main from the power board and then jumper the ps-on pin thru a resistor to 5v pin to turn the power supply on. The backlights should also come on. go from the results, and do some measurements thereafter.
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Old 06-24-2021, 10:29 PM   #4
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Default Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Quote:
Originally Posted by RDC55 View Post
Have you tried the reset?

Hold Vol+ and Ch- while plugging it in?

Curious about the SB pin #24 also, was that low with both Main boards?
Yeah. Tried to reset but not getting it to display anything

Would the reset works even if the board is dead? Or will it only work if the main board is still working?
Pin 24 is 0 on both boards

Last edited by c00lman; 06-24-2021 at 10:40 PM..
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Old 06-24-2021, 10:30 PM   #5
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Default Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Quote:
Originally Posted by budwich View Post
From reads herein, I think that you can disconnect the main from the power board and then jumper the ps-on pin thru a resistor to 5v pin to turn the power supply on. The backlights should also come on. go from the results, and do some measurements thereafter.
Thanks for the reply. Tried to jumper from the 5v to pin 14 and pin 16 (pn-pow). I was able to get 12v on pin 1 and 2
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Old 06-24-2021, 10:37 PM   #6
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Default Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Forgot to mention. When I install the ordered main board. One component is really getting hot to touch as in you will get burned. Measuring the temp with a laser temp. It goes from 27c then increase to 45c and up. It’s q2603 transistor. And measuring the pins. I’m getting 0 ohms which tells me shorted. So I’m suspecting the main board might not be working either. I contacted the store and requested a replacement. It should arrive next week and crossing fingers it’s the main board lol. ��

Then will contact them to return the other board after.
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Old 06-25-2021, 04:50 AM   #7
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Default Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

I think you need to jump it to PS-ON not PN-POW. This turns the power supply on. You should get backlights on and other voltages... all pins should be measured and checked.

It doesn't sound good about the hot component and "0" volts ... but it may be what's connected to that area and not that component ... ie. there is a short in the output / destination... which likely might be towards that panel or tcon itself. You need to posts pictures of the whole backside to show how things are connected and then closeups of the area in question.

Last edited by budwich; 06-25-2021 at 05:01 AM..
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Old 06-25-2021, 09:09 AM   #8
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Default Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Will jump 5V to PS-ON (Pin 14) when I open it up again next week and will measure all voltages.

Jumping 5v to PS-ON, back light should come on?

Last edited by c00lman; 06-25-2021 at 09:26 AM..
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Old 06-25-2021, 09:13 AM   #9
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Default Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Quote:
Originally Posted by budwich View Post
I think you need to jump it to PS-ON not PN-POW. This turns the power supply on. You should get backlights on and other voltages... all pins should be measured and checked.

It doesn't sound good about the hot component and "0" volts ... but it may be what's connected to that area and not that component ... ie. there is a short in the output / destination... which likely might be towards that panel or tcon itself. You need to posts pictures of the whole backside to show how things are connected and then closeups of the area in question.
Does pin 24 should not be 0v?
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Old 06-25-2021, 09:16 AM   #10
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Default Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Heres the pic of the main board and the area of the component that is getting hot. It seems that area is responsible for the HDMI out area.

Will take the pic of the whole setup when I open it up again next week.
Attached Images
File Type: jpg DC28AD6F-DC9A-4664-A320-677140A83D98.jpg (647.9 KB, 15 views)
File Type: jpg 36F88DC1-1C63-4BA6-ADF0-FDEC0193F51B.jpg (542.4 KB, 14 views)
File Type: jpg B500E0FC-6516-4CE5-89F9-4E818CB955B2.jpg (457.7 KB, 11 views)
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Old 06-25-2021, 01:27 PM   #11
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Default Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Quote:
Originally Posted by c00lman View Post
Does pin 24 should not be 0v?
it depends... its the standby pin... IF its not in standby, then its likely to be 0.
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Old 06-25-2021, 01:46 PM   #12
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Default Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Quote:
Originally Posted by budwich View Post
it depends... its the standby pin... IF its not in standby, then its likely to be 0.
Ah ok. when I plugged in. The ps-on has 3v. Just the pnl-pow is not getting 3v from the main board. So it might not be in standby. If I remember. The voltage on the big caps jumps from 130v to 300++

Well see next week when the replacement board comes in. If its still doing the same thing then well see hahaha. Cant find any power supply board replacement anymore.

Thank you
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Old 06-25-2021, 02:01 PM   #13
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Default Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

It looks like Q2603 supplies power to IC 2601. It is labeled to have 3.3V on the emitter and 3.2V on the collector as seen on the schematic on page 14 of the service manual - attached as zip file. Perhaps the HDMI chip is blown loading it and also causing the low ohm readings. The real test would be to check the voltages.

Hopefully, this is encouraging and you just got a bad board to replace your bad board, and the new one in the mail might work.
Attached Files
File Type: pdf Sharp_lc-90le745_series_aquos_update.pdf (1.13 MB, 11 views)
File Type: zip Sharp_lc_90le745u (1).zip (23.37 MB, 7 views)
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Old 06-25-2021, 02:05 PM   #14
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Default Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

This is interesting concerning the LED on the Main board - from the update manual attached above.

"The Heartbeat indicator will flash about every 2 seconds when the Main PWB is working normally. This is an indication that data communications is operational.
The Heartbeat indicator will also flash 1 time when initial AC power is applied"

Last edited by RDC55; 06-25-2021 at 02:14 PM..
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Old 06-25-2021, 04:53 PM   #15
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Default Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Quote:
Originally Posted by c00lman View Post
Ah ok. when I plugged in. The ps-on has 3v. Just the pnl-pow is not getting 3v from the main board. So it might not be in standby. If I remember. The voltage on the big caps jumps from 130v to 300++

Well see next week when the replacement board comes in. If its still doing the same thing then well see hahaha. Cant find any power supply board replacement anymore.

Thank you
the whole point of the test that I suggested is to remove the main board from the system / control so that basically you have the set powering up and creating proper voltages. IF that happens, you can start checking other things by tracing (without powering up) where some of those voltages go from the power board to the main board. Again, lots of this type of problem can be caused by a main board failure but also a panel issue. There are other tests in terms of "cable disconnecting: tcon to panel", etc. That will help determine where a problem might lie.
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Old 06-25-2021, 04:59 PM   #16
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Default Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Thanks. I’m planning to open it next week and follow the test voltage measurements.
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Old 06-25-2021, 08:16 PM   #17
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Default Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Quote:
Originally Posted by RDC55 View Post
This is interesting concerning the LED on the Main board - from the update manual attached above.

"The Heartbeat indicator will flash about every 2 seconds when the Main PWB is working normally. This is an indication that data communications is operational.
The Heartbeat indicator will also flash 1 time when initial AC power is applied"
Thank you, I saw that one too regarding the heartbeat. that's why i'm wondering LOL
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Old 06-28-2021, 05:34 PM   #18
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Default Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Got the board today. Just got it installed, I saw the main board led blink 1 once. The screen flashed and got a new error code . 1 fast and 1 slow.

I will try to open the whole back and get the voltage measurement as suggested. This TV has lots of screws hahaha
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Old 06-28-2021, 07:16 PM   #19
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Default Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Update:

I did the jumper again PIN 14 (PN-ON) and PIN 15 (BU5) without Jumping Pin 16 (PNL-POW). here are the voltages.
Connector to Main board
1-2 0V
5-8 13.05V
13 - 3.04V
14 - 4V
15 5.04V
rest are 0V

L1 Connector:
1 - 16 113V
L2 Connector:
1-26 0V

No Backlight.

when I plugged the Main board and do the force start - Power Channel Down and Volume up.
L1 Connector:
1 - 16 276V
L2 Connector:
1 to 4 106v
7 113V
8 106V
9 104V
13 124V
14 92V
17 106V
19 106V
20 107V
23 107V
24 107V
25 107V
26 107V

when I access the menu, L2 goes to around 92Volts

Connector to Main board
1-2 11.94v
5-8 13.05v
13 3.22v
14. 3v
15 5.04v
16 3.26v
17 0
18 3.27
19. 0.90v
20 3.27V
21 .12V
22 3.26V
24 3.24V

backlight are turning on.

Somehow the regular boot up is detecting there's a failure on the backlight and not going through the whole process. and based on the service manual, there's an option to reset the LAMP count but I cannot access the service adjustment menu

any other suggestion?
Will post some pictures later..... it's on my phone lol
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Old 06-28-2021, 09:08 PM   #20
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Default Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Here are the pics of the board and connection. can't take the whole back as it's standing in the hallway and can't back out more hahaha :P

so it seems if we force it to boot up (Channel down and Volume UP), the TV works, can power off/on, change input, access menu etc. as long as we dont unplug it, it will work.

if we unplug it, then replug, it goes to the 1 slow 1 fast blink. the only way we can make it work is to do the force boot up when plugging in.

Also anyone has a schematic of the power supply? I'm measuring 0 Ohms on D7511 and D7508 (not sure if there's a coil parallel to it LOL haven't done the soldering removal yet).

for the L7502 (C1580) is that a transformer? I'm assuming it should be 0 ohms since it's a transformer? I compared the measurement on the bottom 2 C1543 and i'm getting 0 Ohms if measured on both ends of the terminal..

only if we have some schematics on this power supply so it's would be a bit easier to follow LOL

let me know
Attached Images
File Type: jpg 2021-06-28 17.47.32.jpg (720.0 KB, 4 views)
File Type: jpg 2021-06-28 17.51.53.jpg (727.8 KB, 2 views)
File Type: jpg 2021-06-28 18.11.06.jpg (697.7 KB, 3 views)
File Type: jpg 2021-06-28 18.11.08.jpg (844.6 KB, 3 views)
File Type: jpg 2021-06-28 18.11.11.jpg (541.5 KB, 2 views)
File Type: jpg 2021-06-28 20.53.40.jpg (660.5 KB, 3 views)
File Type: jpg 2021-06-28 20.53.51.jpg (759.5 KB, 4 views)
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