RIP-Felix
Senior Member
NEC/TOKINs are electrolytic/polymer hybrids. However, they have a dry electrolyte, not wet, which makes a difference. Most heat test hypothesis' don't hold up to scrutiny.mm dont know about tokins but electrolitic capacitors will perk up if lightly heatet up, can you try another psu? is psu isnt give the correct power ylod can occur.
On the other hand, there is one theory that holds water. Note: Scientists have a much more rigorous definition for "theory" than the one most people know. In science a "theory" is a hypothesis backed by solid evidence from experimentation and a valid conclusion. Peer reviewed and scrutinized! It is not "just a theory," as people mistakenly say. The corrected saying would be "it's just a hypothesis." It's commonly misunderstood by non-scientists. I'm pointing this out, because I want you to understand what I mean when I say the following is a Theory, not a hypothesis. This is a known phenomenon and not controversial at all. Nor is it my opinion.
There is one lingering theory that can lend validity to the heat test. @Deus brought it up on Page 50. "Capacitors you can revive by heating them up to/above their curie point." I looked into this. It turns out heating electrolytic/MLCC capacitors above the Curie point of its electrolyte does in fact heal them (somewhat). The effect will wear off soon after and can not be repeated very many times due to chemical decomposition (entropy). However, this is one of the the effect that we see in "wet" electrolytic caps and "dry" MLCC's that is the "seed of truth" making the heat test seem particularly plausible. Especially since the NEC/TOKINs are an electrolytic/polymer "hybrid capacitor."
In the case of aluminum electrolytic capacitors the hot liquid electrolyte inside expands and deforms the can itself. It also can strain the solder joints as a result (swelling), which can lower the ESR if it doesn't pop and leak first. That can't happen with "dry" electrolytes, like those used in MLCC's or the tokins.
We have had multiple plausible hypotheses to explain why heat could heal tokins, but all of that goes out the window when an oscilloscope confirms the heat test on bad tokins has zero effect! @squeept did a test that confirms this. So we definitely know the heat test doesn't heal the tokins, not even temporarily.
But there are many MLCC capacitors nearby that it could affect. These are high frequency bypass caps meant to attenuate noise that would otherwise interfere with important signals. If they are going bad, which is unlikely since they last like 50 years, then heating them could restore some of their function. The only scenario I can see this having any affect is if both the tokins and MLCC caps were harmed by excessive heat. Multiple "heat gun specials" from noobs, for example. Then, and only then, could heating the MLCC's above the Curie point potentially heal them enough to restore just enough capacitance to remove the small amount of HF noise causing a YLOD. The effect wouldn't last long because the console was fried and MLCC's basically dead. And it would only work if the tokins were teetering on the edge of working. In that one scenario, the heat test could have meaning and replacing the tokins could fix the problem. And that's only if the BGA were fine, which it most certainly would not be given the abuse it sustained in this scenario.
You really have to stretch the boundaries of plausible scenarios in which the heat test couldd have any meaning. Basically, the heat test is meaningless. Oh, and the SYSCON would read 1002's all day if that were happening. So if the SYSCON didn't, you can know for sure this is not why! If the heat test worked for you and there aren't any 1002's in the error log, then you probaly need a reball.
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