Subj : The smoke got let out
To   : Ky Moffet
From : Barry Martin
Date : Sun Aug 01 2021 07:24:00


Hi Ky!

 > Yup, that's the ending: "smoke got let out".  Good thing was not
 > literally.
 KM> Ooops!!

As long as only an 'oops' and not an 'ohhh sheeeet'....!


 > Last night opened the failed Ethernet switch just for fun -- combination
 > of see what's inside and maybe repair or maybe snag a few parts (I do
 > some electronics hobbyist stuff.)  Did find the problem: two
 > electrolytic capacitors have a noticeable bulge.  Brand is Acon, and
 > yes, they're on the list of manufacturers who had a manufacturing
 > problem years ago.  "Interestingly" the failed cap's are on the load
 > side of a small power transformer while the those on the line side look
 > fine.
 KM> Yeouch. Yeah, failing capacitors cause all manner of weird
 KM> glitches.

And part of the function of a electrolytic capacitor is to remove AC 
ripples and line noise, not create it.


 KM> Couple years ago my old switch failed (it just ceased talking to
 KM> anything, and went from unpleasantly warm to HOT) and I had to
 KM> replace it. Settled on the TP-Link TL-SG108, 8 port gigabit
 KM> switch (at the time about $22), bought from their official eBay
 KM> store, cuz it was handy.

 KM> In fact I liked the first one so much that I promptly bought two
 KM> more (so far!) and left 'em a glowing review. Literally plug in
 KM> anything any which way (auto port sensing so doesn't matter if
 KM> you use regular or crossover cables, nor which cable goes to the
 KM> router), plug in the rather generic wall-wart, and it Just Works.
 KM> Metal body, compact, and generates only a tiny fraction as much
 KM> heat as the old switch; in fact despite that it's fanless, I have
 KM> yet to notice either of the two in everyday use getting warm at
 KM> all, even when busy. I gather this is because any port that's not
 KM> in use goes into sleep mode. Doesn't use enough power to register
 KM> on the UPS.                                                      

The old one hardly generated any sort of warmth either and AFAIK
didn't heat up after the failure either -- 'course the failure in the 
power supply could have fried the switch part and so nothing to create 
heat!  (It looked unharmed; doesn't take much to open junctions.)


 KM> Can also be daisy-chained, as I did initially before rearranging
 KM> what's stuck to the router.
 
Right: the old ones had a specific port for input, and some a mechanical
switch to turn on and off the function.  


 > So with the patched system the live stream videos from the cameras are
 > back to normal.  Have the heat issue still but that's something
 > different.  The 'external accesses' are perkier -- before an ever-so-
 > slight sluggishness had crept in.  Still seems a little odd the one
 > system for monitoring the live stream was the only one showing a
 > problem, and didn't show a problem with packet errors.
 KM> Your attic needs an exhaust fan; that would help a lot.
 
I get voted down on that option.  ...And I'm not recalling seeing any 
house with a fan, not that I'm actively looking and not the fan is on
the other side.  The 'thing' around here, and what we have, is ridge 
venting plus roof vents.  Also a lighter-coloured shingle.


 KM> And bad
 KM> caps can do stuff like make stuff sluggish rather than failing
 KM> entirely. (Eg. slow or spotty USB access = bad caps on the
 KM> southbridge circuit.
 
Right: one of the first things I thought of when everything returned to 
normal was the failed capacitors in the Ethernet Switch are acting like 
a failing Southbridge circuit.


 KM> And I think I just had one such that's on
 KM> its way out sort of randomly scramble a directory when I did a
 KM> normal file save... part vanished, part reappeared somewhere else
 KM> entirely, replacing another directory of the same name, but
 KM> without deleting anything... no files to recover... Well, we
 KM> won't be trusting THAT system anymore...)
 
Or at least the motherboard part!  I could sort of see the scrambling 
and re-arranging: I think directory names (along with everything else) 
are just a 'translation' of the ones and zereos: the 14th entry is 1110 
and there's a table somewhere to say #14 = Pictures.  Flip a binary 
digit to 1010 and now it's in #10 so in some other directory.  (Super-
simplied but close-enough to get the concept across.)


 
                         ¯    BarryMartin3@    ®
                         ¯   @MyMetronet.NET   ®

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