i guess its the main power rails, as it has widests vias. i tried injecting voltage 1v and 1-5a but nothing is getting hot. resistance to gnd is about 0.002 or something like that(will update later). as its the main powerrail, do i raise the voltage to 19v and then inject 1-5amps? thx
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No. The 1 volt should be increased slightly and the process repeats. Do check if the cpu under the heatsink is the fault. Best to check the cpu power rail resistance first. Often will be a shorted cap. Do you have a thermal camera? Ipa alcohol? -
theere is a cpu sockel and the cpu is and is removed(good old days). i have a thermal camera and also ipa. nothing is visible under the camera. i made a mistake in the OP. its 0.2ohms resistance to gnd.Comment
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0.2 ohms is a dead short. Would you have schematics for this unit? One approach is to remove all power, meter in lowest resistance mode, one meter probe at this main power rail with other meter probe at an inductor. What is the measurement? If you see a low resistance then then high side mosfet for that inductor may be leaky. Concern is to review the inductor linked to the CPU power rail. As noted by piernov, if that rail is showing a short then the high voltage from the ~19 v power adapter has travelled onto the CPU power rail and likely killed the CPU but do investigate. If the resistance at the CPU power rail is high then it is ok to keep escalating the voltage used for the power injection along with the current till the bad boy smokes out. Hoping it is a capacitor. Do post your findings before proceeding with the power injection at higher values.
reference:
PPBus_G3H - LogiWikiāComment
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unfortunatly i couldnt find schematics for this board. what would a low resistance be? next to the cpu there are two inductors which where in the Mega Ohms. the rest of the unduxtors where around 30ohms and lower. i removed all mosfets from the board but the short was still present. soldered them back inComment
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The wide traces with 0.2 ohms to ground may be the ground trace itself. That is why no component is heated.Comment
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Or the leads itself what you use or to small and can not give enough current to board. Use thicker wiresComment
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I suppose the real question is whether the existing pinouts from ether a 17IPS71 psu are cross compatible with a 17IPS12 psu? If they are then the exchange of the main boards should have no issues providing the screen is compatible with both main boards. Obviously you can change the screen configurations easily enough (providing you have the correct files) for the main board. Why may you ask would I do this? Well a lot of the smart features are no longer working on a Hitachi 48HBT62U main board I wish to give it a new lease of life!
Obviously the same LVDS connector for the screen connection... -
Hi and thanks in advance for any input you might provide!
I have a Sceptre U550CV-UMRD8POTV83BB 4K LED (this is a dumb tv) that I bought new in August 2021, so It's just completed 3 years.
Main power board model: TP.MS3683.PC821 T-Con board: N4TP546UHDPU2L_BO
Last Sunday I was watching a dvd and fell asleep for about half hour, when I awoke the tv screen was black and couldn't get the dvd menu to show, so I changed the input to antenna and had sound but no picture, turned it off. I then got online and found this great site! ....read many troubleshooting tips and this... -
Hi everyone,
Iām looking for help with a persistent issue on an LG TV model 55NANO77SRA, which uses the main board EBU66792103 (also used in LG UQ80 and NANO75/NANO80 series).
š§© Problem Summary:- The TV keeps scrolling through the menu or selecting items by itself.
- I removed the physical button board (the entire panel with power and volume buttons) and also disconnected the flat cable (CN202) from the main board.
- The remote control is not in use (batteries removed), and the TV still shows the same behavior.
- I
07-28-2025, 08:34 AM -
Hi everyone,
Im looking for some advice regarding my Samsung UE55MU8000 TV with main board model BN94-11606C. The TV suddenly stopped turning on and now shows no signs of life at all not even the standby light at the bottom.
Initially, I suspected an issue with the PSU, so I took it to a repair center. They tested it and confirmed that the PSU works perfectly, even on other TVs. Based on that, I started investigating the main board.
I disconnected the main board from the PSU, and the backlight turned on, which seems to confirm the main board is the issue.... -
Hoping someone here could possibly help. I have a few questions in regards to compatibility with main boards. But I'll give a quick short run down on what's going on first;
I have Samsung Smart TV UA65MU6100WXXY version DA01
Now years ago it started intermittently playing up after a lighting strike. Lighting hit the block of units i was living in at the time. Ever since that night the TV started having a mind of its own, It would randomly turn itself off or on, and all inputs stopped responding like HDMI, aerial, but USB still worked. Anyway, over the next few months...
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