[Tfug] Ezgo "book-PC"

[Ronald Sutherland]

On Tue, May 13, 2008 at 5:09 PM, Bexley Hall <bexley401 at yahoo.com> wrote:

> Hi, Ronald,
>
>
> Sure.  A characteristic of all switchers (hence the
> L in series).


not all, this one may cause a lot of rethinking, its one I've done
automation stuff for over many years,

http://www.google.com/patents?id=TesaAAAAEBAJ&dq=5436818

and yes it works (I don't want to do test stuff any longer so I'm going to
refer to my efforts as automation and control stuff).


>
> They "self-heat" due to high ESR.  Good caps don't
> have high ESR's for a given ripple current (that's
> what the engineer's job is)


I think all caps have some ESR, and sometimes it helps dampen or burn off
the noise, otherwise resistance is added is strategic places. Ripple can be
a different thing than noise, and often its tested separately, but yep ESR
is why they heat up from noise and ripple. Unfortunately the engineer that
did a good job with the design is not the pick and place machine that makes
the supply. Wrong parts, missing parts, damaged parts, board defects and
what not happen, and so noise and ripple happen.


>
> For this particular machine, I can't say -- since I
> don't have the original brick that powered it.
>
> But, I would be slow to accept this explanation.
> E.g., the first machine I found this in was an IBM
> Aptiva.  When told of the symptom (leaking caps),
> IBM didn't argue but replaced the entire board.
> If they had suspected the problem was the power
> supply, they would have replaced that as well.
>
> I think this is just a "bad cap" problem -- but one
> that I haven't (yet) been able to qualify...
>
> --don
>
>
> No problem its good to be skeptical in my book, truth is you are the one
looking at the board not me.
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