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Bugs
in your software? How about mice in your hardware!
Just when you thought you had seen everything, along comes a mouse
wearing a big grin.
On the job, I favor
Okidata LED Page
Printers (this would say "laser printers" except Okidata uses an array
of light emitting diodes in place of the scanning laser typical of the
latter). We have a number of OkiPage 810's, 10's, 12's, and 14's
installed, several of them also have the optional "2nd Paper Tray
Mechanism" attached. Well, not exactly attached - the printer is
aligned over the 2nd tray device and dropped into position.
Alignment pins assure correct location and an 8 conductor connector
provides an interface between printer and tray mechanism.
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An Okidata 14i LED Page
Printer |
The 2nd Paper Tray Mechanism.
Also known as the "High Capacity 2nd Paper Feeder". |
I like the Oki's because they are reliable
workhorses, requiring little in the way of maintenance and most problems
- when they crop up - are relatively easy to diagnose and fix, given a
complete set of factory manuals and a good source of parts (Agson
or directly from Okidata).
So, what's the problem?
An administrative assistant telephoned me
immediately after her lunch break to say that her Oki 14i printer with
the 2nd tray mechanism, which had been working fine earlier in the day,
appeared to be turned "off" and refused to turn back on, despite
repeated attempts with the power switch. I went over to take a
look and pretty quickly determined that the symptoms indicated a total
lack of power getting to the printer's electronics. I first
checked the obvious - loose power cord? power at the outlet?
and then followed up with suggestions from the service manual - PCB
mounted glass fuses okay? power transformer okay?
Everything checked out, but the printer still
would not power on.
It was late in the afternoon and quite by accident
that I found that the printer worked just fine if I removed it from the
2nd paper tray mechanism. Hmmm... Knowing the general
construction of the 2nd paper tray mechanism and the way in which it
interfaces with the printer, I was somewhat surprised that such a
failure was even possible.
I removed the tray mechanism and brought it to my
workspace, leaving the administrative assistant with a working, albeit
slightly crippled, printer.
Hey, who cut those wires?
I had to set this project aside for a few days in
favor of other "to do's"; when I returned to it I began disassembly of
the unit and, 20 minutes later, found the problem - a pair of cut (?)
wires on the aforementioned 8 conductor interface cable assembly.
Now, how did that happen?
There was no immediate explanation. When
assembled, there is no mechanical action in the area of the cut wires
that could have been responsible and there is no practical way that the
wires could have been reached and cut (accidentally or purposely) by the
user without the complex disassembly/reassembly procedure required to
reach them.
A few weeks prior to this episode, the same
administrative assistant was overheard complaining about finding mouse
"droppings" (yeah, you know what I mean) on top of the paper stack in
this very same 2nd tray mechanism. Could it be, I wondered?
Sure enough, my suspicions were confirmed when I further examined the
device and found a severely gnawed area several inches to the left of
where the cut wires were located.
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What possessed a mouse to do this?
The black connector at top interfaces with a mating connector on the
bottom of the printer. One of the alignment "pins" can be
seen just left of the connector.
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Another view of the mouse-eaten cable assembly.
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With the
paper tray installed, the mouse must have been trapped in the
cavity at lower-right. Apparently he (she?) decided to
chew his way out of his predicament
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Once you know the problem, the fix is the easy
part...
I didn't want to bother with splicing the
cut wires so I special-ordered a replacement cable assembly from Agson.
An hour's worth of reassembly and the administrative assistant has been
restored to full printing capability.
But wait! There's more!
So, get this: I bump into our sales
manager in the parking lot one morning and follow him to his office as
we are carrying on a conversation about some long-forgotten subject.
He's standing behind his desk putting his stuff down when he stops and
exclaims, "what the heck?" (you know what he really said).
I won't bore you with the details of the ensuing investigation - the
pictures speak for themselves:
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Our busy mouse chewed away nearly half of the volume control knob on this
Dell PC speaker. Note the grey "crumbs" on the desktop.
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No ordinary mouse, he proved his intelligence by nibbling first on the
computer speaker and then on the nearby telephone's "Spkr"
(Speaker) button.
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So, what's with these mice? In the case of
the printer mechanism, I assumed that a wandering mouse got himself into
a position he couldn't easily get out of and so did what all mice do
when thus confronted - he chewed his way out. But, why chew on the
speaker's knob and the buttons on the telephone?
I have a suspicion that it has something to do
with peanut butter. Both the sales manager and the administrative
assistant are fond of toasted bagels smothered in peanut butter and can
be counted on to enjoy said treat at their desk along with their morning
coffee at least once a week. Everyone knows mice love peanut
butter (try googling "mouse
peanut butter" and see for yourself) and I'll bet dollars to donuts
that our little friends were finding minute traces of the gooey stuff
inside the printer's paper feeder mechanism and on the speaker and
telephone controls, deposited there by our human friends
not-quite-licked-clean fingertips.
The sales manager thinks I'm crazy (nuts?) but I know I'm right about this one. :)
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