Samsung 40" LED UA40D5500RMXXY AC03 cyclic reboot loop

[Orpheous]

I have a Samsung LED TV that cost quite a bit when it was new. Now that it is out of warranty, it's stopped working on me O_o
When I connect a power cord, it displays the Samsung Smart TV splash screen, shows HDMI 2 at the top left corner, then shuts itself off. The red power LED flashes 3 times and it then turns itself back on and repeats the process.

I have tried the following:
* pressing mute, 1, 8, 2, power on the remote.
* pressing mute, 2, 5, 8, exit on the remote.
* removed the stand and the back off the TV, then:
* disconnected all cables and used canned air to blow out all connectors then re-connected them all.
* disconnected just the led backlight - unit power cycles without display.
* disconnected just the mainboard - led backlight remains on and no power cycling.
* disconnected just the T-CON - power cycles
* disconnected the front panel display control board - unit power cycles

I don't have any expensive equipment available here at home, but I have a hot air/soldering station and a multimeter (that I'm still learning to use). I've had experience in replacing capacitors on switching power supplies, pc motherboards and graphics cards etc, and some mobile phone repairs. I like to tinker but am not formally trained, and I'd like to try and figure out what's wrong with this TV without spending any or too much money on it (as I'm a broke single Dad lol)

I have noticed that one of the electrolytic capacitors has a very slightly uneven top, not enough to call it a dome though. They are mostly branded SAMWHA and SAMYOUNG. A few of them are PET also.

Before I go and spend $40 on a set of new capacitors, can you guys help me to troubleshoot it please?

[budm]

Re: Samsung 40" LED UA40D5500RMXXY AC03 cyclic reboot loop

Lets start by showing us good clear pictures of the whole back side of the TV so we can see all the boards and how they are connected together first.

[ozzy214]

Re: Samsung 40" LED UA40D5500RMXXY AC03 cyclic reboot loop

Bad main board. They had a flaw. Causes a reboot. Im not sure what compent on it causes it. I know there is a long list of interchangeable boards that will work on it. Mine I got lucky and found the board for 30 bucks on ebay as one of the known replacement interchangables. Worked ever since

[Orpheous]

Re: Samsung 40" LED UA40D5500RMXXY AC03 cyclic reboot loop

Lets start by showing us good clear pictures of the whole back side of the TV so we can see all the boards and how they are connected together first.

Thank you for replying

[budm]

Re: Samsung 40" LED UA40D5500RMXXY AC03 cyclic reboot loop

Since the backlights come on and stay on when the Mia board is not connected to the power supply board, it means the power supply and the backlights are OK, so the problem is on the main board.

[Orpheous]

Re: Samsung 40" LED UA40D5500RMXXY AC03 cyclic reboot loop

Looks like I'm going to go shopping for a replacement main board...
Can you point me in the direction of a list of compatible main boards for this model?
The current board has the following on it:
BN94-05012Y PTV4(PM) which I think is the part number, but I'm not 100% sure

[ozzy214]

Re: Samsung 40" LED UA40D5500RMXXY AC03 cyclic reboot loop

http://www.shopjimmy.com/samsung-bn9...d8000ffxza.htm

They out of stock, but have 2 known replacements. There is another site that sells boards and list interchanges, but I cant remeber it of hand.

[Orpheous]

Re: Samsung 40" LED UA40D5500RMXXY AC03 cyclic reboot loop

Thank you for the replies. I can't find the UA40D5500RMXXY on the shopjimmy website, and am assuming that it might just be an Australian model(?). If I were to replace the mainboard with an overseas alternative, would it cause issues due to an incompatibility somewhere?
Also, I have found a mainboard for sale that comes from a SAMSUNG UE40D5520RK/UA40D5500RM, part number BN41-01660B BN9405069D
What are the chances of this working in my unit as it's a UA40D5500RMXXY?
The T-CON board numbers are the same for the one for sale and my unit.
I have no idea about compatibility between models :/
Please help if you can...

[dick_barton]

Re: Samsung 40" LED UA40D5500RMXXY AC03 cyclic reboot loop

It is possible that an overseas board may have a tuner not set up for Australian broadcast TV network.

[dick_barton]

Re: Samsung 40" LED UA40D5500RMXXY AC03 cyclic reboot loop

It seems that many of the looping problems have been associated with corrupted EEPROM's. Have you tried freezing it and then switching it on.

[Orpheous]

Re: Samsung 40" LED UA40D5500RMXXY AC03 cyclic reboot loop

I've read online that quite a few of the Samsung LED TV's have had corrupted firmware update issues.
Excuse my ignorance, but how would freezing the mainboard help?
I'm assuming you mean the mainboard as there's no way a 40" TV will fit in my freezer...

[dick_barton]

Re: Samsung 40" LED UA40D5500RMXXY AC03 cyclic reboot loop

Find out which chip holds the Firmware and using either a can of freezer spray or a can of compressed air (used for cleaning keyboards) turned upside down to freeze the IC.

[Orpheous]

Re: Samsung 40" LED UA40D5500RMXXY AC03 cyclic reboot loop

Find out which chip holds the Firmware and using either a can of freezer spray or a can of compressed air (used for cleaning keyboards) turned upside down to freeze the IC.

then turn it on whilst the chip is cold? what will that do to the EEPROM/firmware?

[dick_barton]

Re: Samsung 40" LED UA40D5500RMXXY AC03 cyclic reboot loop

Can you post a sharp picture of your main board. The ones above are too small to identify parts on.

[dick_barton]

Re: Samsung 40" LED UA40D5500RMXXY AC03 cyclic reboot loop

If you are lucky after cooling the chip down then turning on the set, if the TV comes back to life will confirm that it is an EEprom fault.

[Orpheous]

Re: Samsung 40" LED UA40D5500RMXXY AC03 cyclic reboot loop

I'm at work at the moment, and won't be home for a day or two but will post a clearer shot when I get back. Thank you

[capwizard]

Re: Samsung 40" LED UA40D5500RMXXY AC03 cyclic reboot loop

If not the HDMI chip shoted then try this.

[Veteran's Tips] by ReeceyBurger123
Common issue on these boards is bga solder failing on the main processor which is under the heatsink, you could try reflowing it to see if it sorts the issue.....

GPU BGA Reflow (Try this one)
https://www.youtube.com/watch?v=tjWXExWM4RU
Reflow GPU chip
https://www.youtube.com/watch?v=_ywaQ6wPpJw

paint striper heat gun Reballing
Bga Chipset chip change in 4 four minutes.mp4
https://www.youtube.com/watch?v=b7IhprC2wBY

[Orpheous]

Re: Samsung 40" LED UA40D5500RMXXY AC03 cyclic reboot loop

Finally home from work for a few hours and I got a chance to take some more photos.
The main chip seems to have a ceramic looking heatsink attached to it somehow... maybe some sort of thermal glue? Do I need to remove this to reflow the connections to the chip, or should I just heat it up as well?

[Orpheous]

Re: Samsung 40" LED UA40D5500RMXXY AC03 cyclic reboot loop

Quick update:
So I hit the heatsink with my Hakko clone hot air gun and it popped off. It was held on by some white adhesive tape that I imagine is thermally conductive.
I set the air to 240 celsius and heated it up for a minute, then let it cool off before reconnecting it in the TV.
The problem is still there so I'm going to try again at maybe 260 degrees in a couple of days, and heat it up for maybe 2 minutes next time...

[Orpheous]

Re: Samsung 40" LED UA40D5500RMXXY AC03 cyclic reboot loop

I think I'm going to bite the bullet and buy a new mainboard for it...
I can get one exactly the same as the original for AUD$180, but I want to test the power supply to try and reduce the possibility of frying a relatively expensive fix.
Can someone link me to a noob's guide to testing an LED TV PS board please?
Is there anything in particular that I should be looking out for?
I have a UNI-T UT70D multimeter for testing, nothing fancy.