Re: Samsung 40 inch TV -Uncommon Backlight issue.
hi @alfatv & @dick_barton
I checked the IC , it is only receiving the 1.75 volts from from PWM_BLU(4th pin of CNM803) first resistor before the IC and the first pin of IC is only 0.44 ohms, but all other pins show zero volts .(image attached)
Also ,after trying so many angles & lighting, I finally read the IC numbers partially..
SM125*
DA1712
******
Did some research on internet & found the IC is SM1251
I did check you link too ,but then the number I found...
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Re: Samsung 40 inch TV -Uncommon Backlight issue.
@dick_barton
I understand your logic to perform the test ,as i did read earlier how driver IC & MOSFET work but before attempting to short drain & source Just one question-
I am already getting 169 volts at PIN 9 on LED connector and others pins are zero (led connector disconnected-refer post 19 image) , So if we short drain & source to mimic the switching of MOSFET, then how will it reduce the voltage to 101v required by LED's(as per legend on Board-refer post 16). Am I missing the logic somewhere? Also...
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Re: Samsung 40 inch TV -Uncommon Backlight issue.
@dick_barton
Don't know if you read this in my first post .I did something similar but after switching off the TV...
"Help required :Now I think the LED driver IC maybe at fault but again i have no schematics as there is nothing written on the chip ,no matter what magnification level I use, its blank.(Image 3-InkedSamsung PSU3 attached)
I have checked the MOSFET for LED circuit ,that is not shorted but When after switching off the TV ,I put Multimeter red probe to "Drain" and "black probe"...
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Re: Samsung 40 inch TV -Uncommon Backlight issue.
@alfatv
As per your suggestion ,here are the results,
1. I checked the Gate,Drain,Source
TV on Image 1)
Led driver MOSFET-KF3N50FZ
Gate -0 volts
Drain- 113 volts
Source -0 volts
2.Resistance between source and ground when TV is off.(Image 2)
Ground TV-Black probe
Source MOSFET- Red probe
Multimeter set to 200 ohms- gives 1.5 ohms
I have checked few voltages around and have shown in image attached .
The one...
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Re: BIOS for GPU gtx 860M from asus G750JM.
Hi , I have the same Graphics Card GTX 860M ,
May be I can help ,can we copy this from somewhere inside the windows system, through some software? ,
Sorry ,I am not an expert .
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Samsung TV PSU -BN44-00851B
Samsung 40 inch tv powers supply board schematics needed - L40MSFN-FHS BN44-00851B
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Re: Samsung 40 inch TV -Uncommon Backlight issue.
@dick_barton ,Thanks for the video,I did follow this video, but when I disconnected the LED connector ,while TV is turned on and checked the voltage , I get 168.2 to 171v at top pin only and rest all the positive pins as per legend are zero?
As per video for PSU to be okay , it should show the normal voltages at each pin.
Does this mean the PSU is bad somewhere ?
I will check the LED strips again and feedback....
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Re: Samsung 40 inch TV -Uncommon Backlight issue.
Thank you ,okay , I will check the full strip & connector again but Sorry which video link I should refer to ? Also I don't have Led strip checking equipment, What voltage should I be providing to check the strips individually or collectively?
This TV has 3 strips of 7 LED's each....
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Re: Samsung 40 inch TV -Uncommon Backlight issue.
No , they dont flash or come on , thats the issue ,if it either did any of those then it would have been the main board issue. The Samsung technician also said that main board is okay , its the PSU.
and yes the that black box does say LED connector voltages to be 101 v. Image attached...
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Re: Samsung 40 inch TV -Uncommon Backlight issue.
As i explained earlier ,I have individually checked all leds ,None of them are shorted.
The Check method was to put 2.8 volt input at each SMD resistor terminal and each led lit up every time.I triple checked it as , disassembly and assembly is not very easy .
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Re: Samsung 40 inch TV -Uncommon Backlight issue.
Hi Capleaker & Alfatv;
Thank you for your quick response .
The LED connector voltages captured at each pin are attached in the image .
The TV was switched on with all connectors connected .
Sorry But How do we check PFC?Is there any circuit /component I need to check .Apologies ,I only has basic knowledge of electronics ....
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Samsung 40 inch TV -Uncommon Backlight issue.
Hi Respected forum members,
I have trying to resolve a Samsung TV MODEL-UA40K5000ARLXL multiple issue since last 1.5 months, but now i am stuck having tried almost everything as per my limited knowledge, and hence I seek you support.
Issue : The TV turned off automatically one day.
No Backlight ,No image on screen(flashlight test done),no standby
Samsung repair technician could not find the fault and asked to replace the PSU board, which my ego did not agree with
The Board is L40MSFN-FHS BN44-00851B.
I have searched the whole internet...
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