Samsung QE65Q700TATXXC is not starting

[K212]

I'll try to remove the heat sinks.

so this means you think it's not bricked?

[nomoresonys]

Really hard to tell, mainboards are complicated animals, usually not easy to repair. Maybe check youtube for diy reflows, other methods require more tools or sending board out for repair.

[nomoresonys]

Here's Nick's doing a proper processor replacement: https://www.youtube.com/watch?v=x0cnhvliboA

[Davi.p]

The heatsink is easily removed with a tweezer, but don't do it unless you have a real hot air blower, hairdryer is not a tool for repair such electronics, i'm afraid you are not equipped, this Samsung set appears a complex powerful and quite quality set, quiet a waste to let it to start to eco waste isle, think about selling it or giving it for free for parts.. or ask a reballing lab how it will cost full bga ic (ram/emmc/cpu) reball..

[EazyBone]

Read over this thread and the links carefully. This should be the answer. No guarantee but this is probably what it is. I've run into a few now with this board issue and it's always the problem.

https://www.badcaps.net/forum/troubl...aa-won-t-start

[K212]

And what is the cause of this? Just wear and tear or issues in the manufacturing process?

[EazyBone]

Probably cracked solder ball joints. Usually what happens on bga (so I'm told) people have equipment to X-ray it. I do not have that luxury

[nomoresonys]

The heatsink is easily removed with a tweezer, but don't do it unless you have a real hot air blower, hairdryer is not a tool for repair such electronics, i'm afraid you are not equipped, this Samsung set appears a complex powerful and quite quality set, quiet a waste to let it to start to eco waste isle, think about selling it or giving it for free for parts.. or ask a reballing lab how it will cost full bga ic (ram/emmc/cpu) reball..

Dipshyt, the hairdryer is merely a test, GET IT?? It's not to do a repair with. I don't know what kind of wimpy hairdryer you have but the one I have will work for this test and has MANY MANY times. (Never mind, turns out I've been drying my hair with a heat gun)

[nomoresonys]

Here davi boy, just for you, to YET again PROVE that you don't really know much:
A hair dryer used on a Ball Grid Array (BGA) chip can temporarily restore functionality due to a phenomenon called
thermal cycling and its effect on solder joints.


Here's a breakdown of why this happens:

• Weak Solder Joints/Cracks: Over time, especially with repeated heating and cooling cycles during device operation, the tiny solder balls that connect the BGA chip to the circuit board can develop microscopic cracks or "head-in-pillow" defects (where the solder ball and the pad don't form a proper metallurgical bond). This can lead to intermittent electrical connections and device malfunctions.
• Thermal Expansion: Applying heat with a hair dryer causes the BGA chip, the solder joints, and the PCB to expand. Due to differing rates of thermal expansion between these materials, the expansion can cause the cracked or poorly connected solder joints to temporarily make better contact, thus restoring the electrical connection and the functionality of the device.
• Softening Solder/Underfill (Short-Term "Reflow"): While a hairdryer usually won't reach temperatures high enough to fully melt the solder, it can soften it sufficiently to allow the cracked sections to come back into contact. Additionally, some underfill materials, used to provide mechanical support to the BGA, can soften at temperatures achievable with a hairdryer, allowing slight movement of the chip and stress relief on the connections.

However, it's crucial to understand why this is a temporary fix:

• No True Reflow: A hairdryer generally cannot provide the precise and sustained heat required to properly reflow the solder and create a strong, reliable metallurgical bond.
• Mechanical vs. Chemical Joint: You're essentially creating a temporary mechanical connection, not a robust chemical bond that would result from proper reflow soldering.
• Re-occuring Problems: As the device cools down and experiences further thermal cycling, the stresses can cause the cracks to reopen, and the problem will eventually resurface.

Risks and Limitations

Using a hairdryer to "fix" BGA problems carries several risks:

• Component Damage: Applying uncontrolled heat can damage other delicate components on the board or even melt plastic connectors.
• Uneven Heating: A hairdryer doesn't provide uniform heat, potentially leading to warping of the board or further stress on the BGA.
• Dust Contamination: Hairdryers can blow dust and other contaminants onto the circuit board, potentially causing other issues.
• Potential for shorts: If you're lucky, and the solder does melt a bit, it could lead to solder bridging and short circuits.

In summary, while a hairdryer might offer a temporary band-aid solution, it's not a reliable or recommended method for repairing BGA issues. For a proper and lasting repair, specialized BGA rework equipment and expertise are necessary.

[nomoresonys]

So as you can plainly see and what "some people" can't seem to grasp...IS if after this hairdryer "TEST" you get a display, then you know that you definitely have a bga chip issue.

[Diah]

what are you talking more, he had at first #1 shorted ( bridge) PS_ON to GND as his Chat GPT ask him,, MB DC-DC burned out and toasted.. spare time and place of this forum..

[K212]

Iirc, the cable between the mb and psu were disconnected during that test

[nomoresonys]

Ok, so probably was unhooked or might see some damage on mainboard, so test some things.

[Davi.p]

First: Nonorecazzys: do not address to me...
second: the Nomorecazzys guide is not fully true, for my opinion, generally if you can use only an hair dryer then is better than nothing obvious, but if you wish to repair something , and you are here for this, you better get something better than kitchen and bathroom items, for my opinion (not much tested cause its not my job nor an usual hobby now) what does the heat of air is to deoxyding the balls (and this is a chemical professionist hint told to me many years ago), after it the cooling does it in the same directiion but for joule effect (the less temp. the less resistance) , so hear the bell you want from here, as always HERE , the people that starts bikering are not me, i would be happier if the staff notes this and get actions without always my report
third: about the tieing ps-on to gnd, do not mind it , some people has nothing better to do here than to scare some novice, Samsung design normally keeps ps-on to gnd when in standby, then release the contact to make it pulled up and power on..
bye.

PS: when we heat a chip, we do not know how it dilates, the heat can be a better or it can be the cold, usually a cracked joint works better at cold, i remembered now, a good/better measure to combat cracks is to keeps pressed the chips, but you do not know which one so must do it one by one..

[bohaboha]

Hi all it use to be quite easy to remove the black heatsink as many did mentioned above but in my last experience it was very hard to fix it because the heatsink was glued and heat did not help so i used Aceton several times to free the heatsink so be careful