SAMSUNG LED TV UE46B6000 problem

[anno]

Hi

i have SAMSUNG LED TV UE46B6000 tv. the relais are clicking.
i found out, it start then go into shutdown.

power supply is BN44-00269A

i found a shorted FET (Q9103) , in the led driver section of power supply.
i replaced the FET, the Tv started up and worked short . The image was dark so i increased the brightness in menu. Then the tv shut down and same FET was shorted again. how is this possible

I checked the components near the FET and they are OK.
maybe its a bad driver chip? or backlight are using to much current? i thought it has protection when that is?

anyone can help

[Diah]

Re: SAMSUNG LED TV UE46B6000 problem

bad FET i guess

[nomoresonys]

Re: SAMSUNG LED TV UE46B6000 problem

Could be, have to be careful where you get your parts, don't know where you got it but some of those chinese sellers are selling junk.

[budm]

Re: SAMSUNG LED TV UE46B6000 problem

You have 6 boost converter circuits for six LED strings, Q9103 is one of six boot converter, it is possible that you have have some shorted out LED in that string. There is CS pin 5 of LED driver IC to detect over current condition to shutdown the drive to the MOSFET, but it may not be fast enough.
Do you have LED tester to test the Vf of each one of the LED string?
Like other said, it may be bad replacement MOSFET too.

[anno]

Re: SAMSUNG LED TV UE46B6000 problem

Thanks for the info, i got the FETS from ebay (uk seller) . no idea if they are fake or not?
Can i test the LED Strings with adjustable power suplly? i have to limit the current?

can you explain that a little bit more?
if its not possible can you recommend a good led tester? or tester from china (aliexpress) is fine too?

[anno]

Re: SAMSUNG LED TV UE46B6000 problem

I have bought a led tester. How can i test the led strips of this tv?
wich wires ?

[Davi.p]

Re: SAMSUNG LED TV UE46B6000 problem

A basic substitution.for suspected half broken components includes D9102, C9114, R9114.

[budm]

Re: SAMSUNG LED TV UE46B6000 problem

I have bought a led tester. How can i test the led strips of this tv?
which wires ?

https://www.badcaps.net/forum/attach...2&d=1596832161
Notes: You may have to probe the connector from the wire entrance side of the female LED connector.
If you are going to probe from the front side where the female terminals are, you must be careful not to expand the female terminals otherwise they will not make good contact withe male pins header.

Look at the female LED connector that goes to male connector CN9401( Notes: do not plug the female LED connector to the board)

LED string #1
Pin 1 (Blue) = Red probe
Pin 3 (White) = Black probe

LED string #2
Pin 5 (Black) = Red probe
Pin 7 (White) = Black probe

LED string #3
Pin 9 (Blue) = Red probe
Pin 11 (White) = Black probe

Look at the female LED connector that goes to male connector CN9402. (Notes: do not plug the female LED connector to the board)

LED string #4
Pin 1 (Blue) = Red probe
Pin 3 (White) = Black probe

LED string #5
Pin 5 (Black) = Red probe
Pin 7 (White) = Black probe

LED string #6
Pin 9 (Blue) = Red probe
Pin 11 (White) = Black probe

[anno]

Re: SAMSUNG LED TV UE46B6000 problem

thanks.
i checked the led string and they show vF 135 volt . am i doing something wrong or is there a big problem with the leds? shorted?
i get no reading when i check how you said. (blue red probe and white black probe) , i get this reading when reversing .

so Blue - Black probe
white - red probe

[budm]

Re: SAMSUNG LED TV UE46B6000 problem

[QUOTE=anno;981231]thanks.
i checked the led string and they show vF 135 volt . am i doing something wrong or is there a big problem with the leds? shorted?
i get no reading when i check how you said. (blue red probe and white black probe) , i get this reading when reversing .

so Blue - Black probe
white - red probe[/QUOTE

I based the Blue wire as pin 1 per picture.
https://www.badcaps.net/forum/attach...2&d=1596832161
When you plug the cable into CN9401, is the Blue wire on pin 1 or pin 11?
If it is on pin 11, then Blue wires are Cathode.

So all the strings light up and with the same Vf of 135V and they are all steady, correct?
One thing about LED tester, it only puts out about 30mA instead of 100's of mA, so bad LED's may not show up on the test at low current.
You will have to power up the TV with everything all connected back up, then measure the Voltage on each Cathode wire, in this case they are now Blue and Black wires.