Re: [DML] Auto trans governor NO-NO-NOs

["Ralf Philipp" <doc.brown@xxxx>]

.......
> Now in all fairness, if those caps in question had anything to do with
> filtering/smoothing the car's 12VDC supply voltage, in the manner that
most
> electrolytics are used in automobile electronics, and which a reader of
the
> years-long Governor Computer thread would very likely assume from all the
> discussions about them failing from inductive kickback /counter EMF off of
> jump starts and the like (I suspect you assumed this too, Ralf), then I'd
> agree completely on the risk of shorts, heat and explosion from improperly
> installed capacitors
......

Mark!

Your suspicion is true. I never actually saw a GC and I don't have a
schematic for it (I don't need to, because I have a D with manual
transmission). My assumption that the caps in question were used for
filtering the 12V supply was based on hearsay and is wrong. I think, now I
have to apologize. For a really profound analysis I should have taken a look
at a schematic in the first place. Nevertheless, my statements hold true in
applications were caps are used for supply voltage filtering... :-)

Thank you for your detailed explanation of the GC. I now can fully agree to
your statements. A hazard of fire or explosion is only given if there is
enough current flow through the reversed cap. With a high enough series
resistor in front of the cap the situation isn't very critical. I am sure
that this resistor is the main reason why your caps worked such a long time
in "reversed mode".

How about putting an improved schematic in the files section? A while ago
someone gave some clues how to "strengthen" the GC against inductive
kickback etc. Was it you?


Matthew!

Like Mark states correctly, voltage surges are no concern in this
application. So it is absolutely safe to use tantalums. Other than
electrolytic caps, the tantalums will last nearly indefinitely in this
application. But once more: Observe the right polarity. If you are unsure
about the markings on the case: The longer lead is the positive terminal.


Ralf.
VIN10284