Samsung-UN39FH5000FXZA-Will Not Turn ON

[richajem]

Hi forum,
I can use some assistance with a TV that won't turn ON.
When plugging in, the Power red LED is ON and that is the end of it.
It will not respond to the Primary Switch located on the TV nor a remote function.
I did some research before I posted here and so far majority of all problems have been pointing to the Main Board - But here is my troubleshooting outcome. What do you guys think?
Main Board - BN94-06778C / BN97-07695D - 2 separate stickers Manuf/Vendor
PS Board - BN44-00666A
T-COM Board – V390HJ4-CE1
I like to know if there is some additional troubleshooting steps I need to perform to hone into the problem.
I already examined the PS board for swell capacitors and there doesn't appear to be any.
I located the PS connector that connects from the Main Board to the PC.
Here are some voltages that I measured during troubleshooting –
1) Plugged in and Standby mode – Red LED ON
5VA reads - 5.3V
5VB reads - 0.0V
13VB reads - 0.0V
TEST POINT EY80 - 0.0V
TEST POINT EY78 - 17.30V
2) Press the ON Button - Red LED ON
5VA reads - 5.3V
5VB reads - 5.3V
13VB reads - 12.97V
TEST POINT EY80 - 12.97V
TEST POINT EY78 - 14.18V
3) Press the ON Button Again - Red LED ON
Repeated results of Step (2) and it wont change plus I hear a faint high Frequency pitch modulating when it's quiet. No screen image still.

Any help is appreciated.
Thanks,
Richajem

[budm]

Re: Samsung-UN39FH5000FXZA-Will Not Turn ON

Can we see the pictures of the whole backside of the TV so we can see all the boards and how the boards are connected together?
Do you get backlights and backlights will stay on when you remove the cable between the power supply and the main board? If you do then you have main board problem or something is telling the main board not to send commands signals to the power supply board, right now the power supply board is getting the PS-ON becuse you are getting the switched 5VB, and switched 13VB, need to find out if you are getting the BL-ON signal or not.

These are your boards, right?
http://www.shopjimmy.com/catalogsear...?q=BN44-00666A

[richajem]

Re: Samsung-UN39FH5000FXZA-Will Not Turn ON

Hi Budm,
And thank you for read and responding -
Here are the pictures you requested and yes they are of the ones you provided from the link.
In the normal configuration, as described in my troubleshooting steps, there is no backlight appearance.
However, per your instructions, i did disconnect the cable from the main board to the PS board and YES, I have backlight!!
So this does in fact point to a Main Board problem?

Richajem

[budm]

Re: Samsung-UN39FH5000FXZA-Will Not Turn ON

Hi Budm,
And thank you for read and responding -
Here are the pictures you requested and yes they are of the ones you provided from the link.
In the normal configuration, as described in my troubleshooting steps, there is no backlight appearance.
However, per your instructions, i did disconnect the cable from the main board to the PS board and YES, I have backlight!!
So this does in fact point to a Main Board problem?

Richajem

Yes, it is pointed to the main board not sending out the BL-ON to turn on the backlights, so put all the cable back in place and then disconnect the cable between the main board and the T-CON (the big flat black cable) and see if you can turn on the TV with backlights but no pictures on the screen.
BTW, this power supply board has pull-up resistors to allow you to test the power supply board function to help narrowing down the problem which is what we just did.

[richajem]

Re: Samsung-UN39FH5000FXZA-Will Not Turn ON

Budm,

I did tried your last test sequence and there is still no backlight with the T-CON cable removed and with the Main Board and PS cable connection.
I would have thought it should not get the backlight ON when connecting from Main Board to PS Board since the initial issue lies in the Main Board.
Is that a true statement?

Richajem

[budm]

Re: Samsung-UN39FH5000FXZA-Will Not Turn ON

The main board is the one that sends the BL-ON signal to turn on the backlights circuit, but right now the main board is not doing that, the BL-ON is probably stuck low right now due to the main board problem.
You can disconnect just the BL-ON control wire going to the power supply board (everything else hoked back up), if all other functions of the TV are OK, then you should see the pictures, sound, and all the functions should be working, if not then you have more than just BL-ON control signal problem.

[richajem]

Re: Samsung-UN39FH5000FXZA-Will Not Turn ON

Budm,

Thank you, I do appreciate you helping me through these steps-

I see your logic flow Budm.
With the T-CON cable disconnected and the PS connected to the Main Board from the prior troubleshooting step, it appears all issues pointing to the Main Board.
Do you recommend i do your last test step? I'm thinking I need to splice the wire to disable the BL_ON signal line to perform that test all to point to the Main Board. What do you think?

Richajem

[dick_barton]

Re: Samsung-UN39FH5000FXZA-Will Not Turn ON

The wires are held in the connector by a little tab that can be pushed in carefully using a pin or needle allowing you to withdraw the wire from the connector

Push back in with the tab facing the slot in the connector when replacing it. Easy.

[richajem]

Re: Samsung-UN39FH5000FXZA-Will Not Turn ON

Good Advise Dick!! Didn't need to cut and heat shrink the wire. Used a sharp Xacto blade and that did the trick.

The result, as described by Budm-
Back light came on but nothing else worked - So I assume the Main Board is still the culprit?


Richajem

[budm]

Re: Samsung-UN39FH5000FXZA-Will Not Turn ON

Good Advise Dick!! Didn't need to cut and heat shrink the wire. Used a sharp Xacto blade and that did the trick.

The result, as described by Budm-
Back light came on but nothing else worked - So I assume the Main Board is still the culprit?


Richajem

That is correct, if it is just the bad backlights on command signal and everything else are fine then the TV should have all other functions working.
So now you can try heating the main board with hair dryer for a few minutes to see what will happen.
Shopjimmy had the whole 3-board set for around $60 which is really cheap for all 3 boards, but right now he is out of stock.

[richajem]

Re: Samsung-UN39FH5000FXZA-Will Not Turn ON

Budm,

Check this bit of info out!
As I was removing one of the mounting screws on the Main Board, it appears it was under mechanical preload. The board has a slight warp to it which can indicate after heat and Ambient cycles (ON/OFF) components could lose connection.
I wanted to check under the sun for overall condition.

I will reinstall it back and put a heat gun to it. Let me see if I get anything.

But in meantime, i will look for a single Main Board on eBay. Yeah, I seen the board combo from ShopJimmy.

Thank You,
Richajem

[richajem]

Re: Samsung-UN39FH5000FXZA-Will Not Turn ON

UPDATE -

I received the new Main board and it is installed -

The problem is solved and the TV is up and running! Thanks Budm and Dick for your support with the troubleshooting efforts.

Thanks-

Richajem

[budm]

Re: Samsung-UN39FH5000FXZA-Will Not Turn ON

Glad to hear. Thanks for the repair follow-up.

[dick_barton]

Re: Samsung-UN39FH5000FXZA-Will Not Turn ON

As Budm says it always nice to receive feedback.

[nenea dani]

Re: Samsung-UN39FH5000FXZA-Will Not Turn ON

I had the same situation and it was short on 3.3V on processor, NAND or both. Disconnect pin 14 (on / off-power) at CNM803 with a needle. IC201 generates this 3.3V voltage . Probably the main source produces an overvoltage and this defect occurs, which I have encountered several times, sometimes associated with the failure of the LED inverter.