Samsung UN55HU7200 not powering on, no blink code

[withalligators]

Re: Samsung UN55HU7200 not powering on, no blink code

So, shopjimmy got back to me with a pretty cut and paste "sorry, we don't offer technical support at this time" answer. Oh well, any advice one way or the other before I pull the trigger?

[withalligators]

Re: Samsung UN55HU7200 not powering on, no blink code

I saw that too. Neither of them have 3d. Which is why you can never trust anecdotal Internet info.

[dskall]

Re: Samsung UN55HU7200 not powering on, no blink code

This guy seems to think they are the same as well:
https://www.amazon.com/difference-be...sin=B00KJEZIEU

The other commenter says the un55hu7200 does not have the 3D function

[budm]

Re: Samsung UN55HU7200 not powering on, no blink code

I would verify for sure with shopjimmy to see if there is any requirement to do any firmware update if you do use the same original board.
http://www.shopjimmy.com/samsung-bn9...main-board.htm

http://www.shopjimmy.com/samsung-bn9...hu7200fxza.htm

[withalligators]

Re: Samsung UN55HU7200 not powering on, no blink code

This guy seems to think they are the same as well:
https://www.amazon.com/difference-be...sin=B00KJEZIEU

[withalligators]

Re: Samsung UN55HU7200 not powering on, no blink code

Hey guys, quick question: the main in my TV (55hu7200) is the BN94-07917A. The cheapest are around 100 on ebay. There is a similar model, the 55hu7250, with a different part number main board, BN94-07777A (though they're both variants of the BN97-08902A circuit board). This board is 70 on ebay. Do we think they're interchangeable?
My previous experience with Samsung models that only differ in a 50 at the end is that they are for different retail outlets (ie Costco) and I successfully used one main board in the other.
What do you guys think?
Cheers

[withalligators]

Re: Samsung UN55HU7200 not powering on, no blink code

Yessir, same results all around. Am I being hasty by returning the set to SJ? Or should I hold on to it for a few days for testing purposes. Literally everything I've tested is the same.

[budm]

Re: Samsung UN55HU7200 not powering on, no blink code

Do you still get the same result as in my post 6?

[withalligators]

Re: Samsung UN55HU7200 not powering on, no blink code

Interestingly, there's a small button on the main board in the bottom right (SW1200_DB) that when pressed, elicits a click on the power board. Not sure what it's supposed to do though.

Nothing happens with the speakers, BT, wifi, IR, and then disconnected though.

[petehall347]

Re: Samsung UN55HU7200 not powering on, no blink code

what happens with just power cable to to main and nothing else ? do the voltages look correct going to main ?
am wondering if its something silly like a shorted speaker .

[withalligators]

Re: Samsung UN55HU7200 not powering on, no blink code

TV with the back off (all the new components):


Main:


Power:


T-con (heat sink/shield off):


Closeup of pinout from PSU to main:


I'll get around to retesting the pins shortly. Still sounds to me like the main I got is crap. I haven't shined the screen with a light, but it's not turning on. There are no relay sounds, no change in the indicator LED, nothing.

Backlights DO come on if you disconnect the ribbon cable between the PSU and main. This is what makes me believe its not a backlight short / issue.

[vinceroger69]

Re: Samsung UN55HU7200 not powering on, no blink code

Maybe the boards you recived came out of a smashed screen set so they may not of been tested properly it does sound like a faulty mainboard still too me

[xristos glezellis]

Re: Samsung UN55HU7200 not powering on, no blink code

Check for fuse or vatika resistance ohm

[dskall]

Re: Samsung UN55HU7200 not powering on, no blink code

I think we need to start over with do you get image on screen with flashlight?
Need good clear straight on pictures of back of tv with cover off and each board.

Need voltages from connector that goes from power supply board to main board. Will need pin#- PIN DESCRIPTION -Pin voltage in standby-Pin voltage when pushing power button and picture of connector on power supply board.
Format:
Pin# - Pin Description - Pin Voltage standby - Pin voltage power on
1 - XXXXXXX - XXv - XXXv
2 - XXXXXXX - XXXv - XXXv
3 - XXXXXXX - XXXv - XXXv
4 - etc.

[withalligators]

Re: Samsung UN55HU7200 not powering on, no blink code

I've done that. I get voltage change. I also swapped it out for the new button that came with the kit. At this point I've swapped main, tcon, power, Bluetooth, WiFi, ir receiver, and button. So something has got to be bad, right? It's basically a whole new TV, right? If an LED had gone bad, they wouldn't come on and stay on when testing, correct? I had a bad led in a Sammy before, and it would turn on and turn right back off.
Cheers

[dskall]

Re: Samsung UN55HU7200 not powering on, no blink code

Measure your button connector at mainboard for voltage change when buttons pressed. Have you tried with a remote?

[withalligators]

Re: Samsung UN55HU7200 not powering on, no blink code

Hey folks, so, I got sent on a project before I was able to fiddle with this again. While away, I ordered a repair kit from shopjimmy, which included all the boards for a measly 80 bucks. Well, I got back today, and excitedly opened the back of the TV, opened the box, and installed the new main board. Same issue. Perplexed and disappointed, I pulled the cable between the main and power, and the backlights turned on. I then proceeded to replace every component in the TV with the ones from the repair kit. No change in behavior with any component.
So, what do you guys think? The backlights seem fine. Do you think I got a bad main from SJ? They're usually so good.

[budm]

Re: Samsung UN55HU7200 not powering on, no blink code

So you did the power supply/LED driver board self test by disconnecting the cable between the power supply board and the main board and you get the backlights to come on.
Disconnecting the WIFI did not make any different so it means that there is problem on the main board some where.

[withalligators]

Re: Samsung UN55HU7200 not powering on, no blink code

Thanks for the prompt replies. I drove over to work on it. Power board is indeed BN44-00781A main is either BN94-07917A, or BN97-08902A.

Sorry if I wasn't clear before, no readings change when I press the button.

When testing BLU_ON/OFF, I get no reading. I get a negative reading if I put the second probe on UD.

Diconnecting the main and power does indeed turn on the back lights. Testing BLU_ON/OFF turns the back lights off and gives me a reading of about 0.1V (not a digital multimeter). Removing the probe turns them back on.

Diconnecting the WiFi module doesn't do anything. At least, pressing the power button causes no reaction.

I'm on a metered connection right now, I'll get home and post the (terrible) pics of the guts.

[budm]

Re: Samsung UN55HU7200 not powering on, no blink code

PS-ON is working otherwise he will not have the switched B13V so part of the main power supply is working..
PS-ON and BL-ON are Active HIGH in this TV. See if BL-ON is also stuck HIGH.
Which are your boards?
http://www.shopjimmy.com/catalogsear...ung+UN55HU7200
Disconnect the cable between the main board and the power supply/LED driver board to see if the Backlights will come on and stay on, if it does then you have problem with the main board, which then you can try disconnecting the WIFI module to see if the TV will function.