Hi. Anyone who has experience with these vizio sets, which pin on this connector is the standby, the 5V pin? Trying to rule out the PSU before ordering a mainboard. I'm getting 0 Volts on all pins on this connector. Trying to jump the standby and PS ON pins to see if the PSU is functioning. Thanks in advance.
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Did you check the fuse on PSU? Unplug PSU to main board plug and check voltages. But fuse first obviously -
Yeah fuse is good. No voltage on any pins on PSU connector unplugged from mainboard.Comment
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Check the voltage "across" one of the main filter caps in the primary (C9803,04 or 05) If you have +160vdcComment
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I mean, it appears you have a PSU malfunction. You definitely should have voltages. So now you know. Are you trying to diagnose the PSU to fix it? Or just order one.
definitely test the main filter caps, check the octocoupler voltage alsoComment
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And also check the diode at the standby voltage output for a short circuit.Comment
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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.... -
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,
I’m 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).
🧩 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 -
Hey guys great forum glad to have found it. I bought a Sony XBR 65X900C cheaply because it didn't work. No signs of life at all not even a light/led. All I hear is a brief high voltage sound when I throw the power to it.
Didn't see any obvious signs of damage so right away started checking voltages. This is what I see:
Power Board Connector that goes to Main board
CN6401
Pin 01 NC
Pin 02 NC
Pin 03 "BL_ON": 0V
Pin 04 "N/C"
Pin 05 "STBY 3.3V": 3.5V
Pin 06 "GND": N/C
Pin 07 "AC_OFF"... -
ONN 100012588
Issue: No Power, Then Rebooting After Main Board Change
Short answer: replace main board and power board
Technical answer: replace main board and Q306 & Q307 on power board.
Long answer:
TV wouldn't turn on. Power switch was fine which means the main board isn't processing the power on signal. Replaced main board. TV turns on now but randomly reboots. Bad main board? EEPROM? Tried to pull main board and got a shock touching the corner of the board. That's weird. C334 (450V 10uf) capacitor is still holding a high charge....
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