Re: zener diode

Allan Adler <ara@xxxxxxxxxxxxxxxxxxxx> writes:

I decided to take an even closer look at the diode using a pocket microscope
with magnification between 30x and 70x. It helped a little.

Well, that was fun and will lead to future projects. But meanwhile,
I was musing on the fact that the two leads of the second zener diode DZ2
(the red-blue one) each connect to wires that go directly to pins on
the mouse port. I don't actually know which wire is connected to which
pin, so I can't use that information to determine the polarity of the
diode from the pinout of the PS/2 mouse port, but it does potentially
tell me the voltage difference between the two ends of DZ2, just not
the polarity. Then I started wondering whether the other zener diode DZ1
on the PCB is also connected to mouse port pins in this way and reached
for my 7x monocle. That was the right thing to wonder about, since it
turns out that the two leads of DZ1 are connected to the very same mouse
port pins as the two leads of DZ2. Furthermore, unlike DZ2, the markings
on the PCB for DZ1 show very clearly what is the intended polarity of DZ1.
Therefore, I now know the polarity of DZ2 in terms of the known polarity of
DZ1, and I potentially know the voltage across each diode in terms of the
voltage differences between pins of the mouse port.

So, that's progress and, so far, I haven't had to use any test equipment.
--
Ignorantly,
Allan Adler <ara@xxxxxxxxxxxxxxxxxxxx>
* Disclaimer: I am a guest and *not* a member of the MIT CSAIL. My actions and
* comments do not reflect in any way on MIT. Also, I am nowhere near Boston.
.

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