TR103
Member
Last Activity: 07-27-2026, 09:39 AM
Joined: 01-22-2025
Location: Amsterdam
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The picture is more blue than it is in real life, although there might be a bit wear of the LEDS. I took a picture of the screen when it was white, in real that looks OK. I attached a picture of one of my previous projects that did had worn leds, that looked quite different. Both are taken with the same iPhone.... -
Amazing, I fixed it, at least for now! I tried to reflow the two ICs that are actively cooled with the fan (those are the largest ones). That did not make a difference. Then I tried a second reflow, this time the memory chips around those two ICs. That didn't work also, but I noticed that this time the BL was on and the fan started running. Only no picture. So there was change. So I did a final attempt: I gave the memory chips another heat/flux-treatment, and this time the tv immediately started. I will keep it running for a while to see how long it lasts. Now I need to find 8k content :-)...Leave a comment:
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I understand now, thanks for the advice: so a reflow might work, but it might also ruin the chance to reball it later. However, labor in the Netherlands is so expensive that having it reballed costs more than a new MB, and there are few repair shops here as well....Leave a comment:
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You advise reballing, followed by replacing the MB. You are correct in concluding that I am not capable of doing a reball myself. However, before writing off the MB entirely, what would be wrong with attempting a reflow? At this point, there is not much left to lose.
So far, I have not been able to find a replacement MB in Europe at a reasonable price. If the reflow attempt fails, I will probably try to sell both OCB and cable and write off the panel, although it would genuinely pain me to see such an impressive 8K panel go to waste....Leave a comment:
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A reball/reflow is not what I wanted to hear. There are 4 larger ICs and about 5 memory ICs. So I would have to do them all. I don't have the tools/skills for a reball. I might be able to do a reflow, I do have a pre-heating station and a hot air station. And what would be the correct way? Preheat around 140-150 degrees and hot air 400 degrees like 2 minutes till the chip is able to move?Leave a comment:
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I have tested the fan with an external power supply, it does run smoothly. I kept it running for a few minutes. I even tested the tacho-signal, see picture three posts earlier....Leave a comment:
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It is indeed the L2400_FAN. But, I reassembled the tv and I forgot to connect the green cable, and this time it did boot again! The fan turned on and I measured around 3V at the coil. The fan does not turn on immediately. The fan only turns on when the tv boots further than normal, after about 10 seconds. It stayed on during a few minutes and then it crashed and rebooted. In those minutes I saw minor disturbances as if the power was interrupted for a very brief moment. But now it is stuck in boot loop again, with or without green cable, and the fan stays off.
So I guess the components handling...Leave a comment:
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You are right! I measured 5V on the MB but that was not the supply voltage to the fan motor, but the pull-up resistor on the MB to be able to measure the tacho signal. So Pin1=Tacho, Pin2=GND, Pin3=Fan Motor. I checked the fan itself with a separate power supply, and it does spin. The tacho-signal is also present. I attached some pictures: the red dots are all low resistance to each other, like 0,3 ohm (my meter is not that precise). When measuring the resistance between GND and the red dots my meters gives an OL. When I measure at the green dots, there is no connection with the other pins on...Leave a comment:
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It has 3 pins. Pin1 of the fan-connector (grey wire) reads 5V on the MB, the middle pin2 is connected to the GND (black wire), and pin3 (brown wire) is probably the feedback sense signal where the fan tells the MB the speed of the fan.
The interesting part is that the fan is not spinning, although it is supplied with 5V, I will check the connector, the wire and the fan itself. My secret hope is that the absence of the sense signal is causing the TV not to start up. To be continued!...Leave a comment:
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I removed the two black heatsinks, and I found the Winbond ICs, pin8 reads 3.3V (for both ICs), and resistance to ground is approximately 1100 ohm (for both ICs), see photo. So that is probably OK. Also I found a datasheet which confirms pin8 is Vcc....Leave a comment:
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The fan has three wires, I attached a photo. I marked the coil that is without power. I will check the connections as soon as I have the opportunity. Do you think an error will occur when there is no feedback from the fan, which will prevent booting?...Leave a comment:
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Hi Davi, thx for explaining me about the greeting. In the documentation I found the error code just says ''Main Board". Most processing power is in the tv itself: the main board with the four processors with heatsink. I opened the OCB as well, that just seems to handle power and some signal processing for the inputs on the OCB. How do I check CPU supply lines? I couldn't find any power rails without power: I found 12V, 3.3V, 0,8V, 1,8V, 5V. The only coil without power is the one that (I assume) controls the fan....Leave a comment:
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Hi Diah, no the fan was not running, I never heard/seen the fan running. The processors do get warm on the MB, all four of them. The ic's on the led driver boards also warm up....Leave a comment:
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Samsung 8K TV (2018) model QE65Q900RAL, boot loop
I have a Samsung 8K TV (2018), model QE65Q900RAL. The TV does not power on and there is no backlight. The standby LED is on normally. After pressing the power button, the LED turns off, but after approximately 10 seconds it flashes an error code: 1 blink, which indicates a mainboard issue. After that, the TV enters a boot loop: the relay inside the One Connect Box clicks and the cycle repeats.
I checked the mainboard and both backlight driver boards. All voltages appear normal, there are no shorts, and there is no visible damage.
The backlight is controlled via a flat... -
Thanks handsworth! I haven't tried specific that combination, but one of my tries covered more and even then it won't boot. Here are some photos what I tried already. I also tried covering just pin1 (=innermost pin, not on photos), and that is the only way to get it booting, but no picture....Leave a comment:
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Samsung TV model UE50TU: rebooting, backlight, sound, but no picture
Hi, I have a Samsung UE50TU with:
- sound and backlight, but no picture
- when it arrived, it had a picture for a few seconds
- it keeps rebooting
- without ribbon cable between the two panel boards, it does not reboot but I have no picture
- without cable between mainboard and lcd panel, it does not reboot (but obviously i have no picture)
- when i try a tape fix, its keeps rebooting, unless I tape off pin 1 (the innermost pin). In that case it does not reboot but I have no picture.
- without cable between mainboard and lcd panel and with a jumpered... -
Hi I am 53 years old, live in the Netherlands and recently started repairing TV's, for a hobby, to improve my knowledge. And I learned a lot already. I fixed a number of tv's, which is a satisfying feeling when the tv gets alive again.Leave a comment:
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