Re: Diode in Lock Module

[Jan van de Wouw <Jan@xxxx>]

> I currently have my lock module taken apart to "upgrade" the internal
> relays in it. While I was looking over all of the electronics, I
> noticed a yellow diode that was looking pretty bad.
[snip]
> I am somewhat familiar working with electronics,
> so I know how to replace it if I had the proper replacement. However,
> since I'm no electrical engineer I'm baffled as to the purpose it
> serves. It is directly connected to the positive and negative inputs to
> the unit, so I'm guessing that is why it has taken such a beating.

With my knowledge of electronics I would say it's there for protection of
the other internals: it gives negative spikes a way to travel past all
other parts without doing damage...
It can also protect the internals from being wired the wrong way round
by effectively shorting out the circuit and thereby blowing a fuse,
this is the so-called "crowbar"-polarity-protection...

As I see it there are two possibilities why the diode looks fried:
-1 it took a negative current which was too high and/or too long
and the fuse didn't blow
-2 there was positive current that was too high;
higher that the threshold-voltage (the maximum pressure a one-way
valve can hold before the seals collapse to put it simple)
which simply burned out the diode.

I haven't got my original lock-module here right now, but I'll check
this weekend if there are any markings on it for identification.

Greetings and good luck with upgrading,

JAN van de Wouw
Thinking Different... Using a Mac...
Living the Dream... Driving a DeLorean...

#05141 "Dagger" since Sept. 2000

check out the Delorean-Files at:
http://www.deloreanfiles.nl/
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