[weblacky]

Hi All,
I'm currently ordering more desoldering tweezers tip sizes to tackle a repair project given to me (graciously) by user noguri, related to this thread from a while back: https://forums.irixnet.org/thread-1170-p...l#pid13697

I've taken a fairly good once/twice over and I did try it in my Fuel and got both a immediate high voltage alert (like 6.28v on PIMM 5V line) but the start startup test was FILLED with cache issues too (which I didn't expect).  

Now according to my basic multimetering...it has at least one short , maybe TWO shorts, on it.  At first glance I think I see three different VRMs or voltage sources.  Two of theses either share a short or appear to be shorted.  This may explain the HIGH voltage instead of the lack of or low voltage (interaction of the two VRMs in short)?

It MAY be centered around the High Side of one of the VRM buck converters but these use a D-PAK (TO-252) designed FDD6612A (30V N-Channel Power MOSFET) (datasheet: https://www.digchip.com/datasheets/parts...2A-pdf.php) which I need to use desoldering tweezer paddles to remove without damage (intact) in case it's actually functional, but it's a great location to cause a circuit break to further find the short (I won't be simply using voltage injection this time, I'll try a current tracer first!).

Now I have no real proof that if the voltage was solved that cache issues would instantly resolve (the ICs may have been damaged and those are likely not solderable without a BGA machine...).  But I'm hoping that MAYBE the voltage issue caused some kind of trip mechanism (like a protection/clamping diode), to shunt the over-voltage, to protect the cache ICs so once proper voltage is restored...maybe they'll come back online.  

I'll be posting pictures when I do the removal work and isolation.  But I wanted to start the thread because basic checks sure say there's something wrong with these very templated/standard VRM circuits!

Follow me down the endless hole of trying to repair this puppy in a week or so.