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Old 01-20-2022, 12:41 PM   #1
CraigR
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Default Samsung UN55EH6000F Power issue

I got in a Samsung UN55EH6000F with no power and blown fuse on the board (BN44-00499A) I found 3 bad mosfets and a blown resistor circled in the pictures. Now just putting power to the board and checking voltages I get what I need 13v then goes off and on over and over. I connected to TV and TV powers on with sound then off over and over again. I did not include pics of the TV since it is in the power board. So what would cause it to power on and off repeatedly? ?
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Old 01-20-2022, 07:33 PM   #2
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Default Re: Samsung UN55EH6000F Power issue

Check all the diodes and touch up any solder joints that look odd.
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Old 01-20-2022, 07:36 PM   #3
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Default Re: Samsung UN55EH6000F Power issue

Yep, went through all that before posting.
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Old 01-20-2022, 07:51 PM   #4
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Default Re: Samsung UN55EH6000F Power issue

That looks like a gate drive resistor, I would check the zener diodes and the other resistors in that drive circuit.
One of the components you have circled is the standby ic, was it replaced as well?

Last edited by R_J; 01-20-2022 at 08:00 PM..
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Old 01-20-2022, 08:21 PM   #5
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Default Re: Samsung UN55EH6000F Power issue

Quote:
Originally Posted by CraigR View Post
Yep, went through all that before posting.
At least a few still look cracked to me.
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Old 01-26-2022, 02:08 PM   #6
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Default Re: Samsung UN55EH6000F Power issue

Quote:
Originally Posted by R_J View Post
That looks like a gate drive resistor, I would check the zener diodes and the other resistors in that drive circuit.
One of the components you have circled is the standby ic, was it replaced as well?
Yes, it was replaced also.
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Old 01-26-2022, 02:38 PM   #7
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Default Re: Samsung UN55EH6000F Power issue

I found this mosfet (2 legs gone now) with nothing going threw it compared to other one with same number. Anybody know how I can get a good number to get another? WR N7 not coming up with anything on google.
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Old 01-26-2022, 03:24 PM   #8
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Default Re: Samsung UN55EH6000F Power issue

What is the board location?

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Old 01-26-2022, 03:30 PM   #9
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Default Re: Samsung UN55EH6000F Power issue

Looks to be an NPN. If it is sot-23
WR 2PD602R Si-npn GP, Sw, 60V, 500mA, 250mW, B=120..240, >160MHz SOT-23

If you have a component tester, just remove the other one and check it.
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Old 01-26-2022, 03:33 PM   #10
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Default Re: Samsung UN55EH6000F Power issue

.
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Old 01-26-2022, 03:47 PM   #11
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Default Re: Samsung UN55EH6000F Power issue

Quote:
Originally Posted by R_J View Post
Might be 2SK322WR What is the board location?
ZDL802 so must be zener diode and not a mosfet? the N made me think N channel?
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Old 01-26-2022, 04:04 PM   #12
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Default Re: Samsung UN55EH6000F Power issue

Bzx84c24-au
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Old 01-26-2022, 04:04 PM   #13
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Default Re: Samsung UN55EH6000F Power issue

That looks correct, let me guess, they are in the gate circuit.
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Old 01-26-2022, 04:23 PM   #14
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Default Re: Samsung UN55EH6000F Power issue

in the gate circuit
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Old 01-27-2022, 01:52 PM   #15
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Default Re: Samsung UN55EH6000F Power issue

Yep. Thanks for the number! I will order some up and get back with how it goes.
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Old 02-03-2022, 10:48 AM   #16
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Default Re: Samsung UN55EH6000F Power issue

UPDATE: Same thing. 13v then zero just keeps doing it over and over. I was looking it all over again and see a tiny crack in the big green thermister wtr15d050 but I get 8.3 ohms cold so not sure if the crack means damage or not?

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Old 02-03-2022, 12:39 PM   #17
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Default Re: Samsung UN55EH6000F Power issue

What about the A5V is it changing as well?
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Old 02-03-2022, 01:07 PM   #18
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Default Re: Samsung UN55EH6000F Power issue

Quote:
Originally Posted by R_J View Post
What about the A5V is it changing as well?
Yes it is.
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Old 02-03-2022, 01:39 PM   #19
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Default Re: Samsung UN55EH6000F Power issue

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Originally Posted by CraigR View Post
Yes it is.
The first thing I would try is to connect the PS_ON/OFF pin to ground, this should place the power supply in standby mode, then you can see if the standby voltage A5V is stable.
CNM803 pin 14 is PS_ON/OFF

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Old 02-03-2022, 02:12 PM   #20
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Default Re: Samsung UN55EH6000F Power issue

Quote:
Originally Posted by R_J View Post
The first thing I would try is to connect the PS_ON/OFF pin to ground, this should place the power supply in standby mode, then you can see if the standby voltage A5V is stable.
CNM803 pin 14 is PS_ON/OFF
Zero volts 5 nor 13 when when PS_ON/OFF jumped to ground.
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