Newsgroups: sci.electronics.repair
Subject: re problem when replacing cartridge wiper blade in Canon PC-10, etc. or CX laserprinters
Applies to most Canon-based copiers and laserprinters including PC-10, PC-15, PC-20, PC-25, Apple LaserWriter, and many HP laser printers with the Canon CX or PC print engine
W. Curtiss Priest, Director, CITS Center for Information, Technology & Society 466 Pleasant St., Melrose, MA 02176 Voice: 781-662-4044 snipped-for-privacy@MIT.EDU
Technical Repair Note #5 April 4, 2007
Laser/Copier Printers and Copiers
Reassembling the Cartridge
I. Introduction
This is the fifth in a series of technical repair notes for these machines.
Incredibly rugged, there is little that goes wrong with these Canon designed devices.
In an era where prices of new machines are low, and where service costs are high -- re-use and repair has become a lost art.
Yet, there is hardly anything as rewarding and engaging as taking a known and loved machine and breathing life back into it.
And, often, the time to do this is a fraction of the time it takes to either have the item repaired or go about the process of discarding one and purchasing another (with the attendent relearning and "infant mortality" problems associated with acquiring something new).
It is in this spirit that these repair notes are written.
Problem: Paper jams. Location of the jam is at the black pin that has the plastic band resting on it, back side of unit, 5 inches to the right of the inside green felt pad over the fuser roller.
Fyi, repair of the plastic band appears in the news groups as:
Date: 2000/01/07 Subject: re: REPAIRING plastic paper feed strip in Canon PC10, etc. or CX laserprinters
[Note: In subsequent manufacture of the feed strip I note two improvements:- use a "pencil torch" -- this small flame is easily brushed on the pee-wee clip where the jaw arms overlap -- allowing even heating of top and bottom of the clip jaws
Do observe heating only to discoloration, and douse immediately with water. If the (yellow) plastic shows any black, rather than a dark brown, the loop is likely to break
- to improve the weld, I now apply the clip twice -- vertically near one side and then vertically near the other side. This reduces failure due to torsion
Strain test the final result using two pins and, say, a postal scale -- apply 16 ounces. The spring, when in use inside the machine applies about 8 ounces of tension
I note that the original Canon band is superior to using plastic sheet used as report covers. The original band behaves like the plastic used to hold a six-pack of cans together. The kind, that if stretched, narrows and becomes clearer to light. Unfortunately the plastic from such six-packs is too thick. We need 4 mil
Consult the original note for more information
] [Note: After years of cutting a hole in the top of the toner hopper to refill I note that there is a fill plug. That plug can be accessed by cutting a rectangular window into the right side wall at the rear, just in front of a plastic tab that identifies the cartridge to the machine. Place cartridge level with the counter window facing you. Now rotate the cartridge 1/4 turn, clockwise. To the far right are two indents, a tab is typically in the lower indent. Now, 1/8" in from the indent cut a rectangle with a Dremel cutoff wheel that starts just above the "rub" protrusion near the bottom, 1 1/4" high and 7/8" wide.You will see fill cap for the toner. Pop the cap and put a barrel made out of paper, about 3/8" I.D. to guide toner to the opening. Then use a funnel (taped paper, again, is fine -- disposable, only flair the end wide enough for the toner bottle.
Always remember to remove "spent toner" via 2 other cut holes. Symptom of a full "spent toner" receptacle are random drips of black on the print.
Continous black streaking is always a bad silicone wiper blade. Unit must be pulled apart. I've published how to do this as an earlier tech note.]
***Even a twenty-five year old Canon PC copier or laserprinter never jams. Paper pick-up remains reliable even with well over 100,000 pages.
Yes, fuser rollers are no longer used. Heat must go through the paper, making the use of thick stock difficult as the toner rubs off. I compensate by taking a catalytic propane heater (used for removing paint) and waving that heater over the toner if the stock is thick. This also applies to the use of Avery-like self-stick address labels. Also, the feed fingers do score the fuser roller. Toner collects on the tips and abraids the light coating on the aluminum fuser drum. However, one can lightly feather these thin grooves fine carbide paper and the quality is fine. (I used to replace these rollers ... not worth it.)
Only recently did I find one rubber part that goes gooey. There is a tiny roller that is spring loaded against the plastic band (above). That presses on a rubber sleeve on a shaft that turns. To replace this rubber, take a strip of rubber that is about .1" thick, about .4" wide and the circumference of the plastic hub located there. Wrap the hub, mark the overlap, cut to fit. Now take 2 pieces of 25 lb. mono filament fishing line and tie the "wheel" into place. Put the 2 lines about 1/16" from each side and tighten so that they just pull into the rubber enough to be flush. As this is a feed assist roller between the 3 main paper rollers (before the cartridge drum) and the fuser roller, this wheel helps keep the paper taut as it moves to the fuser. Position the knots to fall into the gap. Also use contact cement as a secondary attachment.
I checked two other machines. The PC-10 copier has a rubber sleeve that is still firm. An Apple LaserWriter lost that sleeve and I never noticed. As for the PC-10, this is a splendid copier and because it doesn't use complex optics like the PC-25, the xerographic prints are remarkably clear to the point that it is difficult to tell the copy from the original! It is the back-up copier and also the one I use for very precise reproductions.
***With the cartridge removed, the paper would not jam. One can easily watch the paper move, by removing the cartridge door, two clips and one screw.
Cause: in reassembling the cartridge after replacing the silicone wiper blade, the problem started.
If I left the drum cover off (pop two clips from a guide wire), there was no jamming.
In disassembling the unit the plastic arm that moves that guide wire had become unclipped from it. I noticed it was floppy, but didn't connect to the fact that it should have been held to that wire.
Removing the two 10 mm. torque screws on the counter cover, that arm could be pulled away and then pressed to latch onto the guide wire. (I don't have torque star bits with center holes, so I always grind away the security pin in the center of such screws with a 1/32" diameter chishel tooth carbide cutter.)
When the cartridge is inserted and then the cover of the machine is pressed to latch, there is a sloped plastic arm (often brown) that presses on this lever, opening the drum cover. Of course, the unit could be run without the cover but, while CX toner is non-abrasive and these drums "last forever" -- a single scratch of the drum will make it inferior.
The Canon PC-25 is such a wonder. Elsewhere I have a technical note covering the only serious repair needed -- grease, deep inside the mechanism to change the lense position for reductions and enlargements, gets too stiff -- yes, it is a three hour project to disassemble and reassemble -- but, you need only do this once!