Qn65q800taa won't start

[EazyBone]

Did some of the usual troubleshooting.
Unplug main board connector and back lights come on and stay on and PSU supplies all correct voltages on the legend.

When you just plug in the TV the PSU relay clicks on and off immediately and then continues to click on and off every 20 seconds or so. The red light on the front flashes once and then 5 to 8 seconds later flashes once again and continues the cycle with the relay.

I've disconnected each you ribbon cable one at a time and every single T-Con cable one at a time to see if there's any change. No change as long as the main board is connected. I have also disconnected all ribbons leaving the main board to the panel and the TV performs exactly the same way.

When it is clicking on the PSU the back lights don't do anything and the TV does nothing except for the red light blinking.

Anyone got a clue about this. It seems that the motherboard is a common failure on this TV.

[lotas]

A common problem with this motherboard is processor failure, a high-quality processor reballing is needed.

[Diah]

where are the 2 cable at the t-con side going which under the 2 speaker ?

[EazyBone]

They also go to the buffer boards.

[Diah]

so they are non T-CON data just related to Dimming.

disconnect only both left and right... and disconnect Mainboards to T-CON dimming socket ... let see what you will have... the rest should remain in place

[EazyBone]

Iike this correct? If yes then exactly same. Relay clicks and it still blinks the same

[EazyBone]

So far if I disconnect only the main board from PSU does anything different happen. I've tried a combination of disconnecting everything I possibly could without any change to the symptoms

[Diah]

you have dimming , when you disconnect MB from PSU you have BL. but here the MB monitor to shutdown BL are out of the circuit. i would first suggest to take the screen out to see when at this test you did all Zones BL working as now you just see there are BL

[EazyBone]

One thing I didn't try (and did now) was keep everything connected and unplug the ribbon from top of main to the led driver.

After doing this, the BLs turn on, stay on and then when the relay clicks about 20 seconds, the voltage drops as normal, they shut off and it repeats process. This is different from the usual Samsung rebooting.. at least how it appears anyway. Does this change any opinion?

As for your test Diah do I need to take the screen off or can I just use my tester on the lights and look for voltages?

[Diah]

take the screen off are the best. its just one time , if every things fine then we can dive deep at parts

[Diah]

One thing I didn't try (and did now) was keep everything connected and unplug the ribbon from top of main to the led driver.

After doing this, the BLs turn on, stay on and then when the relay clicks about 20 seconds, the voltage drops as normal, they shut off and it repeats process. This is different from the usual Samsung rebooting.. at least how it appears anyway. Does this change any opinion?

at this point of test do it again but disconnect the Panel complete from T-CON

[lotas]

A common problem with this motherboard is processor failure, a high-quality processor reballing is needed.

[EazyBone]

take the screen off are the best. its just one time , if every things fine then we can dive deep at parts

Noted, I've taken many screens off I guess I can.

lotas do you have any source of this data also? Or just experience?

I see eBay has a repair service for $300 which is just stupid, but if no main boards exist I would be inclined to think it's likely going this way also.

[lotas]

Here is one of the topics, and the same is on Russian forums, that there is a defect in the soldering of the processor....
https://www.eevblog.com/forum/repair...nboard-repair/

[Diah]

when you did the test... did the audio Optic port lit red at time the BL turn on ??

[EazyBone]

when you did the test... did the audio Optic port lit red at time the BL turn on ??

Optical remains red always, it's always on yes, as long as main board is connected.

And thx lotas I'll also read that

[EazyBone]

Started to read that, and that's exactly how my problem is going. At a kids museum but I'll read the rest when home. I don't know other tv repair forums so that's awesome too

[EazyBone]

Pulled screen just because I haven't seen under a 8k screen before. Lights look good. All zones light up

I see why a "good" reflow station is needed for main board. The entire bottom has a giant heat shield on the bottom of it. Although the spot where the IC is open almost every else has it. I'll send a pic with it soon.

[Diah]

Pulled screen just because I haven't seen under a 8k screen before. Lights look good. All zones light up

I see why a "good" reflow station is needed for main board. The entire bottom has a giant heat shield on the bottom of it. Although the spot where the IC is open almost every else has it. I'll send a pic with it soon.

"good" reflow station are nothing, another methode also work perfect, only stencil are the Professional
at the end all Roads drive you to Rom

[EazyBone]

Well I ended up picking up a ir6500 for $100 which I felt was damn good price. So I'm testing with boards currently but seems like it's working pretty good .

[EazyBone]

So was able to reflow the chip and now the same pattern doesn't happen.

Now the tv turns on with backlight, the red light flashes like it's being held down and there is now no picture. Yay 😐

Only did the chip mentioned. I do not have those shorts as mentioned either