Keith C. Perry on 23 Oct 2015 13:20:09 -0700

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Re: [PLUG] OT: wall warts

Yes, electronical systems can and do go bad.  Not in the same way mechanical systems do but there are classes of electronics that "wear".

That wearing is most familiarly caused by heat- specifically the lack of ability for a system to remain "stable" when under excitement (i.e. electrical flow) and to remain durable over a long period of repeated use (i.e. resistance to what I'll just call thermal erosion).

Systems that are involved with power transfer tend to erode quickly over time, not because of heat per se (they can usually handle that) but because current flow slowly degrades the electrical characteristics certain components.  In discrete terms, capacitors tend to fail first, then inductors and then wires (though a wire failure means it has melted which is to say, you had other problems first).  When it comes to more derivative components like transistors and diodes, the erosion takes then components out of spec first before total failure.

I should also say that if it seems like "simple" devices like wall warts are failing more today, you are not seeing things.  The advent of surface mount electronics and advancements in miniaturizing more complex systems has had a side effect of making them more operational fragile as well as less durable over time.  Part of that is simply the trade off of this type of technology and another part of it is also because companies do NOT want you to have electronics that last forever.  In business context, what the electrical world learned from the mechanical world is that you do NOT want to build something that last forever.  In order to stay in business you have to impose some sort of life cycle either through wholesale replacement or regular maintenance for items that wear.  This allows some new innovation to be pushed into the market regularly without consumer demand.

"No user serviceable parts inside" was the end of the "fixer" generation.  It only the rise of the "maker"generation that make once again bring some balance- wall wart died?  No problem... print one !



(sorry for the digression)

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Keith C. Perry, MS E.E. 
Owner, DAO Technologies LLC 
(O) +1.215.525.4165 x2033 
(M) +1.215.432.5167

----- Original Message -----
From: "JP Vossen" <>
To: "Philadelphia Linux User's Group Discussion List" <>
Sent: Friday, October 23, 2015 3:27:13 PM
Subject: [PLUG] OT: wall warts

OT, but I know some folks on the list know a lot more about electronics
than I do.

I was having a problem with a cordless wet/dry vac not charging, which
turned out to be a bad wall wart.  I didn't think those went bad much,
so it took me a while to figure that out.  I have a drawer full of old
ones, so I pulled that out and started testing with my digital Fluke 73
and at least half of old ones showed a flickering more-or-less nothing.
 Others seemed to be around the nominal expected output

I just double checked 2 of them with an even older analog multi-meter
with the same results.

Am I missing something or doing something stupid?  Is there some way one
would only output under a real load?  Some reason my tester would work
on some but not others?  Or do wall warts just go bad more than I think?
 I know they are cheap but the have no moving parts...

JP Vossen, CISSP            |:::======|
My Account, My Opinions     |=========|
"Microsoft Tax" = the additional hardware & yearly fees for the add-on
software required to protect Windows from its own poorly designed and
implemented self, while the overhead incidentally flattens Moore's Law.
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