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sansanpartida
Member
Last Activity: 05-25-2024, 06:45 PM
Joined: 05-22-2024
Location: Madrid
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So far, I'm observing the tester voltage dropping from 300V to 90V each time I touch a connected LED on the ribbon. The light is really faint though. Is this expected behavior? I think I've checked the voltage drop along the entire ribbon but haven't double-checked the light on the other side of the TV each time. Should I verify the voltage drop with a light? My little orange assistant isn't much help, and it's hard to check the ribbon on the backside of the TV and confirm if the LED is on 😅​
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OK, I was afraid of blowing the LED by putting the tester to 300V max Amp… I'll go to my parents' house in a few minutes and keep you updated.
So, to be sure, I'll do the test correctly:
Tester on max settings; positive leads to the center of the ribbon and negative to the 8 outermost pins and see if they turn on.
Is that right?​...Leave a comment:
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I'll test the backlight again tomorrow. I'm exhausted right now. Can someone write me a quick and comprehensive guide on how to test the LEDs to exclude a faulty LED strip assembly? I quickly tested all the ribbons with 84V and really low current, and the light was really faint. I thought that was OK, but maybe that doesn't mean the strip is fine...
Thanks in advance. I really appreciate your help!...Leave a comment:
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Sorry, I don't think I understand your message..
- If I unplug the cable coming from the motherboard and going to the driver board with the TV ON: I read 0.7V.
- Then, as soon as I plug in the cable, I have 1.36V....Leave a comment:
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You are right I have the pin description table and I'm sorry I cropped it on my previous closeup picture I totally missed it. Here it is and you are right it show 3.3V... Do I have so bad luck that I've managed to order a defective driver board? 😥
[ATTACH=JSON]{"data-align":"none","data-size":"full","title":"IMG_8545.jpg","data-attachmentid":3277536}[/ATTACH]...Leave a comment:
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So that is what I have on the 16-pin connector CN9001A. (I didn't measure the serial pins since I don't think a reading with the multimeter will be relevant. Just tell me if I should measure it or scope it.) [TABLE="border: 1, cellpadding: 1, width: 500"]
[TR]
[TD]Pin[/TD]
[TD]Name[/TD]
[TD]Measure[/TD]
[/TR]
[TR]
[TD]1[/TD]
[TD]GND[/TD]
[TD]0V[/TD]
[/TR]
[TR]
[TD]2[/TD]
[TD]SEAMLESS[/TD]
[TD]0V[/TD]
[/TR]
[TR]
[TD]3[/TD]...Leave a comment:
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Ok I've quickly took the measurement..
Here is the picture again to make sure I took the measurement exactly where you told me to (I also took some test points that were just next to it for good measure): [TABLE="border: 1, cellpadding: 1, width: 500"]
[TR]
[TD]PIN1[/TD]
[TD]1,367V[/TD]
[/TR]
[TR]
[TD]PIN2[/TD]
[TD]1,192V[/TD]
[/TR]
[TR]
[TD]PIN3[/TD]
[TD]1,127V[/TD]
[/TR]
[TR]
[TD]PIN4[/TD]
[TD]0V[/TD]
[/TR]
[TR]...Leave a comment:
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Sorry about that. 'Socket of PSU' was too ambiguous for me 😓. I'll quickly do the measurements again.​...Leave a comment:
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[ATTACH=JSON]{"data-align":"none","data-size":"full","title":"IMG_8539.jpg","data-attachmentid":3277479}[/ATTACH]
I can hear sound ✅
I can see an image using a flashlight ✅
Here is a close-up of the connector to avoid ambiguity, since I don't have an FB pin between the PSU and the motherboard. The FB pin is between the PSU and the DRIVER board:
[ATTACH=JSON]{"data-align":"none","data-size":"full","title":"connectors.png","data-attachmentid":3277480}[/ATTACH]...Leave a comment:
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Yes, I set up the tester to 84V and 1mA, put the positive lead in the center of the ribbon, and I got 76.8V on the 8 outermost connectors of the ribbons.
I also tested the voltage on the ribbon when the TV is turned on and found no voltage present. Even if the LED[+] test point show 84V.
BLU_ON/OFF measures approximately 3.2V....Leave a comment:
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Tester just arrived today, and the LEDs seems to be fine. I’m clueless now…...Leave a comment:
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I hope the picture is OK
[ATTACH=JSON]{"alt":"Click image for larger version Name:\tFull view.png Views:\t0 Size:\t8.30 MB ID:\t3276035","data-align":"none","data-attachmentid":"3276035","data-size":"custom","height":"700","title":"Full view.png","width":"696"}[/ATTACH]
Also, here is a picture of the LED driver board. It might be useful.
[ATTACH=JSON]{"alt":"Click image for larger version Name:\tled driver.png...Leave a comment:
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I don't have BL_ON (or perhaps I missed it). The closest thing I have is BLU_ON/OFF, which I measured at 5V when the TV is powered on, as mentioned in my initial post. Additionally, I measured the LED[+] test point on the driver board, and it read 84V.
[ATTACH=JSON]{"data-align":"none","data-size":"custom","height":"222","title":"Artboard 2.png","width":"500","data-attachmentid":3276029}[/ATTACH]
This suggests a faulty LED strip. However, it's odd that I would...Leave a comment:
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One quick question:
I don't have 70 pin ribbon but 68 ones. I also have a cryptic table next each of them, here is a random one (next to CN9001 on the BN44-00991A board)
I believe I have to read the 82' column since this applies to the 82 inches TV model right?
Also, what are those numbers with a minus suffix (-) representing? I imagine + mean the Vdry voltage? (84V)
Here is a picture and a table easier to read.
[ATTACH=JSON]{"data-align":"none","data-size":"custom","height":"833","title":"Artboard.png","width":"500","data-attachmentid":3275934}[/ATTACH]...Leave a comment:
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I don't have a Backlight LED tester... I'll try to get one. This model seems to be really common on AliExpress:
[URL=filedata/fetch?filedataid=338039][ATTACH=JSON]{"data-align":"none","data-size":"custom","height":"250","title":"2dda7cafc7a4d06869e8ae1592f5cb83.jpg","width":"250","data-attachmentid":3275918}[/ATTACH][/URL]
Does it seem OK to you?
In the meantime, I do have a bench power supply, but it will only get up to 30V. Maybe I can get the LED to light up...Leave a comment:
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Samsung QE82Q70RAT no backlight
Hi everyone!
Hope you're all having a great day, and thank you very much for stopping by and taking the time to read this post to help me with my parents' Samsung TV.
My issue: No backlight.
Model: QE82Q70RAT
Type No: QE82Q70RAT
The TV was already serviced by Samsung once under warranty for the exact same issue, but six months after the fix, the backlight went out again. Now, Samsung is asking for nearly the same price as a brand new TV to fix this with the same 6-month guarantee.
So hopefully, I can fix this cheaper.
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Hello!
I'm Sandra, a 27-year-old psychologist living in Spain. While my professional focus is on helping others through psychology, I have a vibrant passion for electronics and various DIY projects. In my free time, I love tinkering with gadgets, engaging in 3D printing, and exploring the art of woodworking. My hobbies not only fuel my creativity but also provide a wonderful balance to my professional life.
I hope to learn a lot in this forum 😉...Leave a comment:
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