Revised 11/09/2005 09:45:30
The Canon ImageRunner 8500 (from here on out called the Canon IR8500) is a
simple joy of a machine to run. It rarely jams, hardly ever malfunctions, and even
when it does, the service techs are actually enjoyable to work with (which is more
than I can say for some other vendors, such as R*COH, eh?). However,
there’s only so much legitimate fun to be had from any machine. To
really get the full enjoyment of the IR8500 (it being no different from any other
machine in this respect), you have to get under the hood. Of course, Canon
doesn’t want you to do this, for entirely-understandable liability reasons: in
fact, service techs can lose their jobs for giving out the code to put the machine into
service mode. (For the record, the code can be found online, so
there’s no reason to go shooting my service tech, okay Canon?)
First, you have to go into service mode. I mean, come on, this is where all the fun
is, right? Service mode in the Canon IR8500 is entered by pressing the
“*” (Additional Functions) button, then immediately pressing
“2” and “8” together, followed by the
“*” again. This is known affectionately as the
“star-twenty-eight-star” among Canon service techs.
If you’re not greeted by a beautiful white screen with a few boring grey
buttons on it, try again . . . and again . . .
and again if necessary. It’s a skill which takes a while to get the hang of, and
even then, experienced service techs sometimes have to do it several times before it
finally “takes.” (To exit service mode, press “Reset”
several times until the machine returns to normal, end-user menus.)
Before you go pushing any service-mode buttons on your dear old IR8500, let me
give you a friendly little WARNING: by entering service mode, you
automatically incur the disfavour of the entire multinational Canon corporation, your
friendly neighborhood service tech, and your boss (if you mess anything up). That
said, let’s dig in.
Viewing the Analog Sensor Data (temperature, etc.)
Menu: COPIER > Display > ANALOG
Just hit the “Copier” button (the top one) upon entering service mode.
The first panel/tab it drops you in ought to be the “Display” tab. From
there, hit the “Analog” option. There’s not much to do here,
but it’s actually where I spend most of my service-mode time. When the
copier’s warming up, there’s not a whole lot to do; so you might as
well watch the fuser temperature rise, right? Here are your readouts: pick your
- TEMP (ambient temperature, °C)
- HUM (ambient relative humidity, %)
- ABS-HUM (ambient absolute humidity, g/m3)
- OPTICS (optics temperature, °C)
- FIX-C (fixer center temperature, °C)
- FIX-E (fixer end temperature, °C)
The ambient temperature (TEMP), is, of course, the temperature of the room
around you, as measured from somewhere in the copier itself (and as such, it has a
tendancy to be a tad high: for example, it usually gives me a reading of 23°C on
a 21°C day). The optics temperature (OPTICS) is measured in the optical
chassis, in the top of the machine. They are kept heated, mostly to preclude
condensation, to around 75°C. The higher the relative humidity, the higher this
temperature should be, I assume.
The relative humidity (HUM) is the most reliable measurement of humidity (and
of course, will be a tad low, since the temperature it is measured with is a tad high),
since it is independent of pressure and temperature effects on air volume.1. The
absolute humidity (ABS-HUM) gives you the current mass of water per cubic meter
of air, and as such, is affected by barometric pressure (because barometric pressure
affects the volume of a given mass of air or other gas).
The fixer temperatures (FIX-C and FIX-E) are the temperatures of the center and
ends of the top fixer (or, fuser) roller. I had originally thought that they were top versus bottom rollers (FIX-E is usually about 10°C cooler than FIX-C — ~187 as opposed to
~197°C — os I figured that that FIX-C was the bottom roller, the extra heat
compensating for its indirect contact with the toner, since only the top roller directly
contacts the unfixed/unfused toner), but a friendly Belgian Canon engineer read this post and corrected me.
It’s mildly amusing to watch the fixer/fuser temperature rise as the copier
warms up, but other than that, there’s not a whole lot of action here. Now if
you want to actually feel like you’re doing
something . . .
Cleaning the Corona Wires
Now, in recent versions of the IR8500 copy machine firmware, Canon has
provided a user option to clean the corona wires. However, this procedure is
probably a pale and insipid version of the actual cleaningr process, since they
don’t want ordinary people doing anything which could potentially harm the
machine. Reasonable. Do I let that stop me? No. Here’s how an
honest-to-goodness Canon service technician gets the black lines out of your
copies. (Yup. If you have streaked copies and you’ve already wiped off the
fuser/fixer rollers, but to no avail, this may do the trick without a visit from your
Menu: COPIER > Function > CLEANING > WIRE-CLN
This will take a few minutes, but it’s almost guaranteed to get rid of streaks
and lines in your copies if they were even remotely caused by dirty corona
See, the corona wires have to provide an even electrical charge (static electricity)
to the sheet of paper so that it picks up toner powder evenly. If there is something on
the corona wire causing a stronger charge at one point, that may result in a line
across the paper where the sheet passes across that part of the corona (electrical
field). See How
Stuff Works for a detailed explanation of how the xerographic process (the
process used in photocopiers and laser printers) works.
Viewing the Maintenance Counters
Menu: COPIER > Counter
The ImageRunner 8500 keeps track of the wear and tear of nearly every replaceable
part. A counter is incremented for every copy (or, “click”) in which a
given part is involved. For some items, such as the cleaning web, this means that the
counter is incremented with every copy. Other parts, such as paper takeup rollers, are
used only intermittently (i.e. only one paper storage drawer is drawn from per copy),
and therefore have counts far lower. Counters are reset when a part is replace
(ideally, though I have some parts which show a 1,000% overuse simply because
their counters have never or rarely been reset when they’ve been
Oh, and that’s the other cool thing about the counters. They give you
the percentage lifespan used for each counted part. Has your tech been doing his
job? Now you know.
Other Miscellaneous Schtuff
- Errors and Jams: these items give you the time an error code was set and
the time it was cleared, along with the code itself and the size of paper involved
(third, fourth, sixth, and ninth columns, respectively).
- Function > MISC-P > P-PRINT: a seven-page printout of your
current machine parameters and software package versions, along with your
maintenance counter readings: the “Copy Service Report”
- A whole lot of other things. Just don’t break anything, okay?
Hope you’ve enjoyed this little exposition (or, expoundification,
perhaps?). Remember, I am in no way liable for any damage you may do, which may
result in your service tech laughing at you and charging you double. If you want
someone to blame, you can find the service code online sometimes.
Anyway, I didn’t make you do anything, eh? (But speaking of making
you do stuff, there’s some more service-mode tips and tricks for the
ImageRunner series at the Imaging Systems Group
“Canon Black and White Products” pages.
Humidity is the amount of water saturated in air (or another gas).
Absolute humidity gives the mass of water vapor per unit volume of air in the
atmosphere, while relative humidity is the ratio of the partial pressure of water which
is actually present to the vapor pressure of water at that temperature, expressed in
— Wolfram Research,
Absolute humidity is the mass of water vapor per unit volume of air in
the atmosphere. The mass of water at any given temperature is limited by the vapor
pressure, which can be found in tables of water properties. A more useful notion is
that of relative humidity.
— Wolfram Research,
According to Dalton’s law, the pressure of a gas mixture is
equal to the sum of the partial pressures of the gases of which it is composed. In the
atmosphere, water vapor always contributes a partial pressure to the total pressure,
usually expressed in terms millimeters of mercury (or inches of mercury). At any
given temperature the partial pressure of water can never exceed the vapor pressure
for that temperature, otherwise it would condense into liquid water.
The relative humidity is the ratio of the partial pressure of water which is actually
present to the vapor pressure of water at that temperature, expressed in percent. For
example, if the local atmosphere has a partial pressure from water vapor of 5 mm of
mercury and the temperature is 20°C, the relative humidity would be (since the vapor pressure of
water at 20°C is 17.5 mmHg).
— Wolfram Research,
How Stuff Works
What if you had to resort to making carbon copies of important
documents, as many people did before copiers came along? Or worse, imagine how
tedious it would be if you had to recopy everything by hand! Most of us don't think
about what's going on inside a copier while we wait for copies to shoot neatly out
into the paper tray, but it's pretty amazing to think that, in mere seconds, you can
produce an exact replica of what's on a sheet of paper! In this article, we will explore
what happens after you press "Start" on a photocopier.
More at How Stuff Works, “How