My Samsung will not turn on, just a solid red light at the power button on panel. I tried pulling plug to reset, nothing. There is no clicking when trying to power on on the tv panel. I opened it up and there are no blown/bulging caps. I am considering replacing the main board. I do not have access to a meter to test the power board. Is replacing the main board a good start?
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Re: Samsung LN40B640R3FXZA Will not turn on
Can you post some pictures of the overall circuit board layout of the set? Main board failure on this set is common, but other faults exist, too.Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
For service manual, schematic, boardview (board view), datasheet, cad - use our search. -
Re: Samsung LN40B640R3FXZA Will not turn on
Also the P/N of the power supply board, I.E. BNXX-XXXXX.Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
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Re: Samsung LN40B640R3FXZA Will not turn on
See pics. Also the P/N for power board is BN44-00264A. The main board is BN41-01149B.Attached FilesComment
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Re: Samsung LN40B640R3FXZA Will not turn on
Without a meter even simple tests on secondary fuses are out.
Even cheapo 5-10$ would do.Please upload pictures using attachment function when ask for help on the repair
http://www.badcaps.net/forum/showthread.php?t=39740Comment
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Re: Samsung LN40B640R3FXZA Will not turn on
OK, the power supply-inverter board has built-in pull up resistors for the PS_ON and the BL_ON, so disconnect the cable between the power supply and the main board, the backlights should come on when you APPLY 120VAC to the TV.Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
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Re: Samsung LN40B640R3FXZA Will not turn on
Disconnected the main board from the power board and the backlights came on.Comment
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Re: Samsung LN40B640R3FXZA Will not turn on
probably a bad main board -- need DMM to confirm.Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
For service manual, schematic, boardview (board view), datasheet, cad - use our search.Comment
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Re: Samsung LN40B640R3FXZA Will not turn on
I will get my hands on a multimeter. Once I get it, where should I test on the board to confirm?Comment
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Re: Samsung LN40B640R3FXZA Will not turn on
I got my hands on a Fluke MM tester. Where should I start on the main board?Comment
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Re: Samsung LN40B640R3FXZA Will not turn on
First, check the power supply output voltages - 13V and ~5.4V - are OK.
To do this, place your probe on the pin corresponding to that voltage with the connector out. (TV powered on - backlight working. Do not touch any part of power board!) Note voltages.
Then, turn power off, plug in main board connector, and check voltages again in a similar manner. (Press probe onto join where sheath and wire meet, it's a few mm in.) Note voltages.Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
For service manual, schematic, boardview (board view), datasheet, cad - use our search.Comment
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Re: Samsung LN40B640R3FXZA Will not turn on
My LN46B630N1FUZA has the same main board.
Anyone know what components are at fault?Comment
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Re: Samsung LN40B640R3FXZA Will not turn on
I do believe a shorted T-con could also stop the Tv from switching on, I would hook it all back up again but this time disconnecting the T-con from the main board(it's the board sitting at the bottom), see if it powers up after doing so.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,
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 -
When plugged in it will click and cycle the BL on and off, no pic and does not respond to remote. When I disconnect the cable from the PS board to the main board and then plug it in the BL will come on and stay on. There are only two boards in this set, the LVDS cables from the panel driver boards connect directly to the main board. Since the BL comes on and stays on I'm thinking the PS board is ok and the problem is on the main board. Should I order another main board or do I need to do more testing? thanks, Lee -
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"...
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