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Script
Please follow along as you view the video. The script has been annotated to help you find reference information in THE INTRAVIA’S SERVICE GUIDE TO XEROGRAPHIC IMAGING EQUIPMENT.
As you watch the tape, we hope you will take your time and refer to pages listed in italics for thorough explanations and for related information. To help you keep your place and to be able to easily match the script to the tape, we have tried to put items in the video that are being pointed in the script in bold print.
We have placed reference information in italics. So, if you want more information on a particular subject, the paragraphs in italics will tell you where to look to find that information in the THE INTRAVIA’S SERVICE GUIDE TO XEROGRAPHIC IMAGING EQUIPMENT.
You will encounter some areas of black screen or frozen image. These were necessary to align the video and audio.
FUSER UNIT REBUILD
During this section, we will remove, disassemble and rebuild a fuser unit. We will also test some fuser components.
For an explanation of how the fuser works and what it does, see pages 20-24.
For text on disassembly, go to pages 89-92.
For illustrations of fuser components, go to pages 10, 20-24, 77, 78, 89-92, 158, 159 and 165.
Removing the fuser unit. This fuser unit removes from the machine quite easily. We open the doors, drop the transport, release the latch and slide it out. This is convenient, as we can now carry the unit to a comfortable work surface. Some units do not remove as easily and some do not remove at all. There are some where it is easier to do the work in the machine.
This fuser unit is relatively difficult to work on, compared to most others. Consider this to be an example of how to rebuild a fuser unit, not necessarily a step-by-step lesson. We will attempt to show you all components, which, although not identical to all fusers, are quite similar.
We now remove the rear contact lamp holder and then the front lamp holder. This lamp has wires and does not use electrodes as some do. Unfortunately, we appear to have lost or moved to quickly through some of the steps here.
With the fuser unit out, we remove the cover……PAUSE… (in the tape, sorry)... ………………………………………………….and remove the cleaner roller.
Since this lamp has wires, we now have to unwrap and remove all wiring. This is a rather difficult procedure on this machine. It only takes about 30 seconds, and if we felt like doing multiple takes, we could probably do it more smoothly, but in the real world of copiers, you would go through the same thing.
As you remove the wires and clips, make a note, or at least a mental note, of how they are routed. When you reassemble, you don’t want to let wires get pinched, cut, stretched etc. Also, before removing the lamp, note which connector goes at each end. In some cases they are color coded. In any case, you would hate to assemble it backwards and then have to redo the work to install it properly.
Remove the snap-ring.
Remove the e-ring on the gear. Typically, one gear holds another in place. We are replacing most of these gears, which you might not always be doing. It is quite common to have to remove several parts to get to the ones you are changing.
To remove the heat roller, we will need to release the tension put on it by the pressure roller. Use a long nose pliers or spring-hook to unhook the springs. Some machines will not require this step. In most cases, the springs are pressing directly against the pressure roller, rather than pulling against levers.
Now that we have the pressure released, we can slide out the fuser bearing. Don’t be surprised to find the bearing stuck in the housing. Tapping, hammering, prying are not that unusual.
For illustrations of fuser bushings and fuser bearings see page 23.
Slide out the heat sleeve and bearing in the front. If you are replacing the heat roller, I would strongly recommend replacing the heat sleeves. In many cases, you will also replace the bearings. If this is the case, you don’t have to worry about whether you can separate them from the roller or not. If you are reusing parts, remove the other snap-ring.
Here is a view of the thermistor. Most look like this, but not all.
For information on fuser thermistors see pages 20, 24, 91, 171 and 174.
For illustrations of fuser thermistors see pages 10, 21, 91 and 171.
On a typical fuser rebuild, you do not necessarily replace the thermistor. You would clean it, whether in the machine or out. Most are a square yellow pad like this one. Some look like small wires with toner on them. On that type, what looks like toner is actually the thermistor, so be careful about what you scrape off. On this type, you can safely remove the toner, but be careful not to damage the surface of the thermistor.
Here is how I clean a thermistor. The metal screwdriver can easily damage the thermistor, so scrape very carefully. Use liquid cleaners as well to soften and remove toner. Toner on the thermistor, such as you see on this one, causes inaccurate temperature readings, and can even cause the fuser to overheat. Remove all the toner you safely can. It does not have to be perfectly clean, but the cleaner the better.
Here is the fuser thermofuse.
For information on thermal fuses, see pages 21, 24, 91, 158, 165 and 175.
For illustrations of fuser thermoswitches see pages 21, 91 and 165.
Now we are looking at the thermoswitch.
For information on thermoswitches see page 99.
To test a thermofuse, set the ohm meter on a low scale. Note that the video mistakenly has the meter on the high scale. Also, be sure to test your meter before continuing.
Disconnect at least one lead from the item. Read across the device. You should read 0 ohms (dead short). If you use a higher scale, you could get a misleading reading, because a few ohms on a very high scale might display as 0. If the thermofuse reads open, it is definitely bad. If it reads short (0 resistance) it is probably good. It is not unusual for a component to test good, but not work under load.
Note: Testing electrical components is described in detail in the "Practical Electricity" section beginning on page 149.
Here is the thermoswitch. Testing it is the same as testing a thermofuse.
Illustrations of thermoswitches are on pages 21, 22 and 92.
Testing the thermistor.
For information on testing the thermistor, see page 171.
Since the connector is very small, our meter leads wont fit, or won’t stay in place, so I will use a paper clip to insert into the connector, being careful not to damage the connector. Connect your meter across the unplugged thermistor and set to the highest possible scale. At room temperature (probably abut 70 degrees) you will get a reading.
As mentioned earlier, an item that passes a test is considered probably ok, but not guaranteed to work. If you read a complete open or short, the thermistor would be bad. For now, note the reading. If we change the temperature of the thermistor, the resistance reading will also change. The easiest way to heat the thermistor surface under test conditions is to use body heat. My little friend here will supply the heat. The difference between room temperature and 98.6 is enough to make a noticeable difference in the thermistor reading.
So, here we go.
Note that the thermistor resistance goes down as the temperature goes up. That is because this thermistor, like most, has a negative coefficient.
Remove the fuser’s lower cleaner roller. It is attached to this plate. Note how it is packed with toner.
For an illustration of a toner-packed cleaner roller, see page 22.
We will also clean the feed-in plate. This plate guides the paper to the fuser nip. The nip is the meeting point of the two rollers. If the plate has a toner buildup, it can result in wrinkling, skewing or jamming. You can also clean it with a strong solvent on a rag, but scraping is faster. However, scraping the plate with a metal tool may scratch its surface, if you are not extremely careful. You might prefer to use a plastic ruler or plastic putty knife as a scraper.
Upper fuser pawls. Remove the mounting plate. On some machines, the pawls are replaced one at a time without removing any other parts of the machine.
Lower fuser pawls. Remove assembly.
For information on fuser pawls see page 23, 89 and 90. (They are also described as “separator fingers.”)
For illustrations of fuser pawls, see page23, 89 and 90.
Lift out the pressure roller. If reusing the press roller, you would want to clean the built up toner from it. Glass cleaner will work, but something stronger is preferable. However, whatever you use, you will find the job much easier if you also use a scotch-brite pad. This will remove toner very quickly. Do not use it on a heat roller though; it will ruin the coating.
With the press roller out, we can see the pressing levers.
Here is the exit switch actuator.
We are going to install a new pressure roller. However, the new one does not come with hardware. We will remove the shaft, bearings and e-rings from the old one to reuse in the new one. As you see, the shaft did not come out easily and had to be forced out. Inspect the condition of the bearings to be sure they are capable of being reused.
New fuser pawls are installed, one at a time. Unless you are very sure of yourself, don’t remove all the old ones until you have installed at least one new one. It is very easy to get confused and install them backwards, upside down or pointing the wrong way.
Reassemble the fuser pawl plate to the other sheet metal plate. Reinstall the pawl mounting plate along with any other items that may have been removed.
Install the new heat roller, being very careful not to scratch it. Before doing so, be sure that you are not installing it backwards. It is very frustrating to be nearly finished and have to take it all apart and do it over again. I know. I’ve done it.
Although not shown, you would next install the new heat sleeves (bushings).
Install the new bearings. In some cases, you will assemble the heat sleeves and bearings to the roller and then install the complete assembly in the fuser unit. However on this machine, we insert the roller first, and then add the bushings and bearings from each end.
Replace all the gears in the correct sequence. Generally, it is impossible to put them in the wrong places. They will usually not fit on the wrong shaft or will not mesh properly if installed in the wrong place. It is possible to put them on and not be able to get one of them on until you remove all the others again. Be on the lookout for drive pins inside the gears that are easily dropped or misplaced. This unit did not have any such pins.
When installing the large fuser drive gear, note the drive pin that fits in the slot. Some gears use screws that thread into a hole on the heat roller.
Be sure all snap-rings, e-rings etc. are in place and positioned properly.
Fuser lamp. To test the lamp, set your ohm meter on a low scale and read from one end of the lamp to the other. One ohm is a correct reading. If the lamp looks badly discolored (experience will show you the difference between badly discolored and slightly discolored) it should be replaced, even if it tests good. Remember, a lamp that tests bad is definitely bad. A lamp that tests good is only probably good.
For information on testing a fuser lamp see page 158.
For illustrations of fuser heat lamps see pages 158 and 159.
Reinstall the lamp, being sure that you put it in with the front and rear in the correct locations. Dress the wires carefully.
Reinstall the lower cleaner roller bracket with the new cleaner roller.
Reconnect the press roller springs. This is most easily done using a spring hook.
Install the top cover.
Examine the machine on the test bench to see that there are no pinched wires, no missing screws, no pawls out of position, no wires caught in gears, etc.
Reinstall in machine and test.
Pretty horrible copies. These are caused by a bad drum blade. We will go through replacing a drum blade on this particular machine and see what result we get.
For information on drum blades see pages 11, 14, 25, 56 and 70.
For illustrations of drum blades see pages 7, 11 and 26.
First, of course, we open the door and open the clamshell. Then, we slide out the developer unit.
Remove the toner waste bottle.
Next we will remove the drum/cleaner unit. To do so, we need to remove the mounting screws and unplug the connectors. The connectors are tough to get out.
Removing the charge corona will give us some more room for the fingertips to get in there. Part of the problem is that the video camera is looking at my hands and I am not able to without blocking your view! With the charge corona out, we unplug the connector, and slide out the drum/cleaner unit.
As you can see, there is toner all over the drum; rotating the drum does not wipe it off. This machine has a fixed cleaner blade (one that is in contact with the drum all the time) and if the blade were OK, the drum would be cleaned even rotating it by hand.
We will now remove the drum.
For information on drum removal, see pages 86-88.
We have to remove the screws from and rotate the drum shaft on the front, and then slide it out.
After removing the drum, we want to protect it from becoming damaged or scratched and we need to protect it from being out in the light, which can also damage it. We will wrap it in newspaper and put it in a safe place.
For information on drums see pages 7, 11, 37, 45, 46, 86, 87 and 88.
For illustrations of drums see pages 37, 45 and 87.
To remove the blade, we first have to remove the cleaning lamp; however that step was not recorded for some reason.
For information on cleaning lamps see pages, 11, 14 and 60.
For an illustration of a cleaning lamp see page 160.
With the cleaning lamp out of the way, the next step is to remove the three screws that hold the blade in place. After doing so, this blade is still pretty tightly in place and so we will work it out with a spring hook.
We now open the new blade and install it, using the three screws.
We now reinstall the cleaning lamp board.
We reinstall the drum, being very careful, as always. The drum is still coated with toner. There is no reason to wipe it clean. The blade will do that. Also, the toner acts as a lubricant between the new blade and the drum. If we did not have the drum coated with toner, it would be a good idea to use starting powder on the drum. Wiping the toner off the drum could also scratch the drum, depending on what you used to wipe it. Drum surfaces are quite easily scratched.
For information on drum installation and removal, see pages 86-88.
Installing the dirty drum adds to the "drama" of what you are about to see. As we rotate the dirty drum, with the brand new blade, see how the toner is perfectly wiped off the drum.
For information on priming the drum see pages 87 and 88.
In the case of a new drum, new blade or both, you may have to coat the drum with starting powder. Some machines have routines or specific procedures for priming the drum, so that the new blade and/or drum does not get damaged in the first few rotations. If you know them, you should use them, but you can't go wrong doing it this way either.
To prime the drum, keep patting it with the starting powder until the entire drum surface is covered. If the new blade has no powder on it (many come pre-powdered) apply some to the edge of that as well. Install the drum and continue.
In either case (primed drum or toned drum) we are now ready to install the drum/cleaner unit. We slide it in and reconnect the plugs
This is the toner waste bottle full sensor. As the bottle fills, it gets heavier, sinking down until it breaks the beam of the photointerrupter in this unit, signaling the machine that the waste bottle is full.
For information on toner waste bottles, see page 11 and 26.
For illustrations of toner waste bottles see page 26.
Reinstall the charge corona and reinstall the screws.
We close the clamshell, reinstall the developer unit and turn the machine back on.
Here is the copy that comes out. Next to it is the copy that we made previously.
Replacing paper feed tires is a common repair. There are many different types of feed tires and we can't show you all of them, but we will replace them on this machine.
For information and illustrations on paper feed units, paper feed tires, etc. see pages 15-17 and 92-94.
We get the "P" symbol indicating there is no paper, but when we open the cassette, we see that there is paper.
On this particular machine, we remove the entire paper feed unit from the copier. There are about five screws holding it in. We must first remove the transfer corona, which is held in with one screw through the rear. We remove that screw and slide out the corona unit.
After removing the other mounting screws and unplugging the connector, we lift the paper feed unit out of the machine.
These are the paper feed pickup rollers.
For information and illustrations on paper feed units, paper feed tires, etc. see pages 15-17 and 92-94.
Lift one end of the paper feed tire shaft and peel off each of the pickup tires.
Here are new tires to install. We will install one on camera. The others are all installed the same way.
Reassemble the feed unit and reinstall it into the machine.
Reinstall the transfer corona.
Make a test copy.
For information on cleaning optics, see page 3.
We will first remove the glass.
Remove the screws. Remove the lead edge guide.
Lift the glass off. Make at least a mental note of how the glass goes in. This covered section goes towards the front.
With the glass off, remove the black lens cover.
Clean the area around the optics first.
Clean the mirrors and the lens that are under the lens cover. Some machines will have a slit glass in this area as well.
Clean the black cover before you reinstall it, only because its dustiness looks sloppy. It will have no direct effect on the copies.
Now clean the other parts of the exposure system. Clean all mirrors using a soft rag (such as a piece of a T-shirt. Paper towels can scratch mirrors.) In tight spots you can use a Q-tip.
To get to the exposure lamp and its reflector, we need to move the light baffles. Loosen them, and slide them out of the way, but note where they have to go back to when you are finished. You can usually tell by the screwhead marks in the baffles.
One way to clean under the exposure lamp, without removing it is to do this. Apply some glass cleaner to a paper towel or piece of paper and slide that under the lamp, helping along with a flat blade if necessary.
Clean the underside of the glass with glass cleaner and paper. Don’t use rags. They will cause streaks.
Reinstall the glass, being sure it is correct. Reinstall the lead edge guide and screws.
Now with the glass safely in place, go ahead and clean the top surface.
Be sure to clean the document cover as well. It is one of the first things that the customer sees.
Also, clean the exterior of the machine as best you can, within a reasonably short time.
Open the front door and slide out the slit glass on this machine. Clean it with glass cleaner and a paper towel.
Developer unit is removed and reinstalled by mistake. The unit should have been left out of the machine.
Slide out the developer unit and set it aside.
Remove the toner waste bottle.
Remove the toner waste bottle bracket.
Remove the drum shaft retainer.
This machine happens to have a waste toner cap to prevent it from dribbling while you are working on the machine. Go ahead and cap the waste toner tube.
For information on removing the drum unit, see pages 86-88.
Inside the machine, unplug the drum cleaner solenoid. Unlike the previous machine, this one has its drum blade activated by a solenoid.
See the drum.
Slide out the charge corona.
For information on the charge corona see pages 2, 7, 8, 11, 12, 57-59, 62, 66 and 170.
For illustrations of charge coronas see pages 8, 57, 81, 83 and 169.
Having already removed the drum shaft retainer, we can now slide out the drum shaft.
We will now lift out and slide out the drum/cleaner unit.
Off camera, we lifted out the drum (no tools were needed) and wrapped it in paper, as we did on the previous machine. The green colored item is the drum blade. The blade opposite it (hard to see on film) is the seal blade, also known as recovery blade.
For information and illustration on the seal blade see page 64.
Here is how the solenoid is actuated.
Here is the blade being operated by the solenoid.
Looking inside.
This is the cleaning lamp assembly.
For information on cleaning lamps see pages 11, 14 and 160.
For an illustration of a cleaning lamp see pages 11 and 160.
These are the blanking lamp LEDs, whose job it is to erase unwanted image on the drum between copies, on the edges in reduction and so on.
For information on blanking lamp, see pages 59, 63, 112 and 160.
This is the transfer/separator corona assembly.
For information on the transfer corona see pages 9, 13, 18, 19 and 61.
For illustrations of transfer/separator coronas see pages 11, 19, 63, 80 and 170.
These are transport belts that help carry the paper to the fuser.
Here is the fuser; the upper roller, the lower roller, the upper pawls.
This is the exit switch and these are exit rollers.
Replacing developer
For information on developer see pages 9, 38, 39, 58 and 84-86.
Now back to the developer unit. Clean off the exterior before you start, with brush and yellow rag, just to make it more comfortable to handle.
Remove the toner hopper from the unit. It is held in place by two screws.
For information on toner hoppers see pages 39 and 84.
Remove the screws and unplug the connector to the toner feed motor.
Remove the toner hopper and set aside.
This is the developer in the unit.
This is the mag roller.
For information and a schematic representation of the mag roller see page 38.
We will now empty the old developer.
To do so, we will pour it out of the unit, turning the gears on the back to help to empty the developer.
As you can see, the developer in the unit is pouring out and the mag roller is becoming more and more bare of developer as we do so.
Always have some newspaper or drop cloth to keep your mess on. I don’t believe it is very nice to just dump it directly into their garbage. When done emptying the developer, wrap it up in paper and double wrap it, and set it aside. You will probably be throwing it away, but every now and then you may find that you brought the wrong developer with you, and are forced to reuse the old stuff.
This is the doctor blade, though it is hard to see.
For information on the doctor blade and schematic representation see page38.
These are the augers that keep the developer stirred up.
Open the new bottle of developer. This one has a seal inside of the cap. Be sure to get rid of all of this seal. A little piece of paper that is not removed could wind up in the developer, stuck in the doctor blade, causing white streaks in your copy.
Install the new developer by pouring it evenly through the entire empty unit. The unit will sometimes appear to be full before you are finished. That is because of the developer that has not yet been rotated onto the mag roller. Rotate the mag roller to carry some of that developer onto it and now there will be room for the rest of the developer.
Reinstall the toner hopper. Note the tabs on the hopper that go under the tabs on the developer unit; don’t forget the plug. Install the screws.
Sharp AR-160 toner & drum.
Here is another machine to see some routine items on.
On this machine, the entire toner & developer unit is a disposable cartridge. It slides right out of the machine.
Toner goes in this section.
This is the toner waste bottle.
For information and illustrations on toner waste bottle, see pages 11 and 26.
The drum cleaner unit also slides out.
This is the charge corona.
This is the tube that carries waste toner from the drum cleaner unit to the waste bottle on the t/d unit.
Xerox 1012
Here is another machine to see some routine items on.
Here is a fuser unit removal which is quite different from most.
Remove the cover at the front end.
Move the on/off switch out of the way.
Remove the plastic bracket.
Lift the fuser unit up.
Remove the screw in the rear.
Remove the plastic cover in the rear; it is held in rather snugly.
Undo the wires.
Work the fuser unit out.
Disconnect the front fuser lamp connector.
Remove the unit and unplug the rest of the connectors.
Remove the transfer corona on this machine by pushing one way and releasing tension on it.
The developer unit slides right out.
Exposure lamp removal. We removed the covers off camera, because it did not seem necessary for you to see. What we wanted you to see is that this machine provides an access hole for exposure lamp removal. Move the exposure unit to this spot, release tension on the electrode with a spring hook, and you can then work the lamp out through the front. Notice the green corrosion on the electrodes. This should be cleaned off before reinstalling the lamp.
Board removal
For information on board removal, see page 95. For illustrations of board, see pages 167, 168, 173 and 174
Unplug the connectors. As you can see, some require you to release tension on them first. Some pull right off.
Undo the clamps that keep the wires together.
In this case there is a ground wire connected to the board. We will remove that from the frame.
To remove the board from the machine, you must compress the plastic pins and pull the board over them. I use a long nose pliers.
Paper feed tires
Here is a somewhat unusual method of changing paper feed tires. After removing the cassette, developer unit and drum unit from the machine, stand it on end. There is an access hole in the bottom frame. Reach in through the cassette section to rotate the feed tire assembly to the correct position, and then remove the one screw that holds the assembly in place.
Another optics unit
With the glass off this machine, you can see a thermistor that tells the machine if the glass is getting too hot. But what we really want to see is the scan cable. I just want you to see this one, which is pretty typical, so that you understand why you should be very careful not to mess them up. It is routed very precisely and would be quite difficult to reinstall if you did not have a factory service manual.
1st surface mirrors.
For information on mirrors see pages 44, 56 and 100. For a graphic illustration of a 1st surface mirror see page 44 and 100.
Only one surface of the mirror is used. The first surface. Note how the business side of the mirror reflects the screwdriver precisely. The other side shows a different image, one that would result in copy quality problems. If a mirror is removed, this is how you would determine which side does the work. For some silly reason, I wanted to show how easy it is to scratch a first surface mirror, so I rubbed the screwdriver tip against it. The first surface is very soft; even cleaning with a paper towel will sometimes scratch it.
Another paper feed unit
On this machine, we remove the right side panel to access the paper feed pickup roller.
We pry out the white plastic roller.
Push out the white plastic bushing.
We can now remove and replace the pickup tire assembly.
Simulation procedure/developer calibration
For information on developer calibration, see page 85. To see what operation panel symbols of developer, maintenance, etc. look like see pages 52, 75, 192 and 193.
Each machine requires you to know exactly how to enter simulation mode and especially what the exact developer calibration; aka toner concentration, developer setup, auto toner sensing procedure is. Here is the procedure on one machine as an example. This procedure will not apply to others.
We will first cheat the front door switch so that we can perform the adjustment.
On this machine, we enter simulation by pressing a particular sequence of keys. Clear, 0, 0, clear. Then, for developer setup, we press 2, than 5, than Print. With the front door switch cheated, and the machine running, you will observe the display; the toner waste bottle is lit, indicating that we are in this mode. As we run the machine, the toner light may or may not light or flicker, depending on the status of the developer concentration at that moment. Here we see it flashing, indicating that the concentration is correct. Remember, this does not apply to other machines.
Rewiring a corona
The illustration of this technique is on pages 82 and 83.
Making a loop. In some cases, you need a loop of corona wire to hook onto an existing pin or hook. To do so, use a 2mm hex key. Loop the wire around it at the right angle. Maintaining an approximate 90 degree angle on the wire, twirl the hex key a few times. Then cut off the excess. Here is your loop.
Rewiring a corona.
The illustration of this technique is on pages 82 and 83.
Remove the old wire, trying not to lose the spring, though you should carry spares at all times. Reel off some new wire. Hook the spring into it and keep about a 90 degree angle with your fingers. Twirl the spring a few times. Tug on the spring to be sure the wire will not loosen. Take the spring and hook it on the stationary screw. Stretch the wire across the corona to the other screw, going clockwise around it. This way, when you tighten the screwhead, it will tighten the wire as well. When appropriately tightened and stretched, break off the excess wire under the screw head by wiggling it back and forth. Snip the excess wire off the other end with a good quality pair of wire cutters. There should be no pig tail (excess wire) sticking out after you do this.
Here is a corona grid.
For information on corona grids see pages 57, 58 and 83.
For illustrations of a corona grid see pages 8, 57, 83, and 169.
Here is a transfer/separator corona.
Here are the plastic fingers that prevent separated paper from falling into the corona.
Here is a corona block that has had some arcing. If you look carefully, you will see black patterns. Those are actually burn marks; the result of the corona arcing.
Here is a badly burned corona block, removed from a copy machine.
This is an example of a Pin corona. The metal sawteeth are the equivalent of the corona wire.
Here is a corona roller, which comes in direct contact with the drum.
This is a high voltage transformer, which would normally be mounted to the frame of the machine. The corona unit plugs right into this.
For information on HVTs see pages 59, 66, 169 and 170.
For illustrations of an HVT see pages 168 and 169.
The corona has a banana pin connector on it to plug into the HVT.
Paper feed clutches
For information on clutches see pages 15, 16, 93, 94 and 164.
For illustrations or wrap-spring and magnetic clutches see pages 16, 94 and 164.
Note that without the clutch being engaged, the tires do not turn. When we manually engage the solenoid (simulating the machine's paper feed signal) the tires make one revolution.
This is a wrap-spring clutch assembly.
Remove the e-ring to begin removing the clutch.
Slide the clutch off.
Note that there are five holes in this section of the clutch, and the tang of the clutch is in the center hole. You would want to know and to write down which hole it is in, as the wrong one is likely to cause feed problems.
Separate the sections of the clutch, GENTLY. It is very easy to damage a wrap spring.
Note that the other part of the clutch has three holes and the tang is in the center hole also.
Clean each piece.
I like to use a piece of scotch-brite on the hub to make sure there are no burrs or high spots.
Clean the wrap-spring. Then lubricate it lightly.
Reassemble the clutch.
Reinstall the clutch.
Install the e-ring.
Test manually, by rotating, engaging the clutch, etc.
Here is what a good wrap spring looks like.
Here is a bad wrap spring. However, they can be bad and look good sometimes.
Here is another type of wrap spring clutch assembly.
Here is my model of how a wrap spring works. Pretend these are two separate shafts. As you can see, if one is turning, the other could be slipping. However, once the spring wraps tightly, everything moves as one unit.
Magnetic clutches
For information on clutches see page 59. For illustrations of wrap spring and magnetic clutches see page 16, 94 and 164.
These two disks, nearly touching, can spin separately.
Once they are pressed together, the surfaces lock and they spin as one.
In an electromagnetic clutch this part is the electromagnet.
When it receives power (usually 24 Volts DC) the two steel or iron plates are drawn together, providing drive.
Here are the plates that engage.
This is a locking point to keep the clutch from moving on the frame when it is being driven.
This is a set screw, which locks the clutch assembly to the shaft of the item it is driving, such as the paper feed tire shaft.
Fuser components
For information on fuser units and fuser components see pages 3, 10, 13, 20-25, 77, 78, 89-92, 171 and 172.
For illustrations of fuser components and fuser assemblies see pages 10, 11, 20-24, 77, 78, 89-92, 158, 159, 171 and 172.
This is a badly worn heat roller.
This is a heat sleeve, also known as a bushing.
In some cases, the bearing fits right onto the roller.
Some machines will use a stationary bushing such as this one.
This is a thermistor. This type of thermistor is always in direct contact with the heat roller.
For information on fuser thermistors see pages 10, 20, 23, 91, 171 and 174.
For illustrations of fuser thermistors see pages 10, 21, 91 and 171.
This is a badly worn thermistor.
This is a thermoswitch. Thermoswitches are in direct contact with the heat roller.
For information on thermoswitches see pages 10, 21 and 91. For illustrations of fuser thermoswitches see pages 10, 21 and 22.
This is a thermal fuse. Some are supplied like this; with connectors and a heat resistant sleeve over them. Thermal fuses are NOT in contact with the roller. They are generally about 1/8" away.
For information on thermal fuses see pages 21, 24, 91, 96, 158, 165 and 177. For illustrations of fuser thermal fuses see pages 21, 91 and 165.
For information on fuser pawls see page 90.
For illustrations of fuser pawls see pages 23 and 90.
This is a thermal fuse as it appears without the wrapping.
For illustrations of fuser thermal fuses see pages 21, 91 and 165.
This is a Triac, as frequently used to power the heat lamp. The small contact is the DC trigger. The other two are for the AC lines, but they are not interchangeable. The wires must go to the correct pin.
This is also a fuser triac. It is much smaller, and is soldered in place.
For information on triacs see pages 21, 24, 172 and 175.
For illustrations of a triac see pages 21 and 172.
This is an SSR; solid state relay. These are also used to operate fuser units.
For information on the SSR see pages 77 and 172
For an illustration of an SSR see pages 22, 77 and 172.
This is a drum wiper blade.
For information on drum blades see pages 11, 14, 25, 56, 60, 70, 87, 88 and the detailed procedure earlier in the video.
For illustrations of drum blades see pages 7, 11 and 26.
This is a microswitch. This might be used as an interlock switch.
This is a microswitch that might be a paper path switch.
Here is another microswitch with a different type of actuator.
For information on microswitches see pages 160 and 163.
For illustrations of microswitches see pages 161, 162.
This is a reed switch. The contacts are in here.
For information and illustrations of reed switches see page 162.
This is the magnet that opens or closes the contacts.
Here is a switch problem that is not at all obvious. These are identical, but look carefully at the one on the left. This is a paper path switch whose actuator has been worn down by thousands of sheets of paper rubbing against it, resulting in false jams.
This is a photointerrupter "flag." The item that breaks the light beam.
Here is a photointerrupter that we have broken, so that you can see the internal components. However, even up close it is hard to see anything.
A photointerrupter consists of an LED and a photosensor in the same assembly. When the light beam is broken or seen, the machine knows that something is happening.
For information on photointerrupters see pages 105, 106, 163, 164 and 176
For illustrations of photointerrupters see pages 105 and 163.
This is commonly called a PT disk, pulse generator or encoder. It rotates with its little windows passing through a photointerrupter. The PI sees light, dark, light dark, etc. at a certain pace or frequency. In addition to the photointerrupter getting dirty, the window/slits on the disk can also get dirty; dust, spider webs, etc.
For information on the PT disk see page 106.
For illustrations of the PT disk see pages 106 and 165.
Lamps
Here is a heat lamp that is bad because it is discolored. We don’t care about the color, but experience shows that this lamp will work only intermittently.
Here is a heat lamp with a broken filament.
Here is a heat lamp with burn marks on the inside of it. This lamp is also no good.
For information on fuser lamps see pages 20, 21, 24, 78, 90 and 175.
For illustrations of fuser heat lamps see pages 78, 158 and 159.
Here is an exposure lamp. Note that it is frosted. Not all exposure lamps are frosted, but most are.
For information on exposure lamps see pages 8, 12, 27-29, 41-43 and 55.
For illustrations of exposure lamps see pages 27, 29, 41, 43, 158 and 159.
This exposure lamp has burn marks on the inside of it. This lamp needs to be replaced. When you have burn marks, copy quality suffers.
Digital copier
We are going to look at the CCD. The CCD is the Charge Coupled Device. It receives the optical image, converts it to digital pulses, and sends the pulses by cable to the machine's logic boards. The logic boards create the 1s and 0s which are used to write to the laser to put the image on the drum.
For information on CCDs see pages 8, 36, 37, 121, 123, 124, 138 and 143.
For illustration of the CCD see pages 6, 30, 36, 100, 123 and 124.
Optics servicing is similar to an analog copier: Remove the glass and then remove the CCD cover, which is the equivalent of a lens cover.
These don’t get dirty very often, but here is how you would clean them. Remove the plastic CCD/lens cover. Clean both sides of the lens with a Q-tip. Note the red screws. Never touch those. They have to do with a factory adjustment that you might not be able to do if you move them. Clean the CCD surface with a Q-tip as well. Be very careful. A tiny piece of lint or dust can cause a substantial copy quality problem.
Here is a view of a CCD.
Fuser unit. Remove the right side cover. The fuser is mounted by three screws, though we only show one being removed. Next, unplug the connectors from the rear frame. Remove the fuser.
Laser printer
We are removing the side panel so that you can see what we are doing. However, there is no reason to do so to remove the developer unit or drum unit.
Lift out the developer unit.
Lift out the drum unit.
(These are both operator jobs and require no tools or expertise.)
To remove the fuser, you would want the developer and drum units out of the machine, as well as the side panels off for easy access.
Remove the screws that mount the fuser to the base plate.
Unplug the connectors.
Lift out the fuser.
Laser unit removal
For information on laser units and polygon motors see pages 34, 35, 54 and 66.
For illustrations of laser units, polygon motors and other components of laser units see pages 6, 7, 33-35 and 66.
Open the clamshell and remove the cover.
This laser, like most, is held in place with about three screws. Removal and replacement is very easy and straightforward. Remove the screws and connectors.
Laser units are usually meant not to be serviced. They frequently have warning labels on them. They do occasionally need cleaning, as dust can get on the mirror or lenses. In any case, you want to see the inside of one, so here we go.
Open the cover, usually by prying the little snaps that are spaced around it.
Here is the laser board that interfaces with the machine, whether it is a copier, printer or fax.
Here is the laser diode, which creates the laser beam.
Here is the lens which focuses the laser beam.
Here is the polygon motor or laser motor, which is rotating at probably about 15,000 rpm in most copiers.
For information on laser units and polygon motors see pages 34, 35, 54 and 66.
For illustrations of laser units, polygon motors and other components of laser units see pages 6, 7, 33-35 and 66.
Here is the collimating lens that distributes the reflected image, one line of dots at a time.
Here is a mirror or two (depending on which machine) that reflects the line of dots to the drum, through a slit glass.
Here is a beam detect mirror. At the end of each row of dots, the laser beam strikes this mirror, which reflects the beam through this lens and into this photocell, which tells the machine that the laser unit did its job properly, for that particular line of dots.
Here is another laser unit.
We will pry this one open as well. There is the rotating mirror. Here is the lens.
Here is the beam detect mirror, which reflects the end of the beam through this lens into a fiber optic cable which does the same thing as the photosensor in the previous laser.
Here is a copier logic board.
Note the many IC chips, LSIs. This also has a battery to retain memorized settings.
This is a VR, variable resistor. However, it is pasted from the factory. That means it is not a field adjustment.
For information on logic boards (main boards) see pages 102-104 and 172.
For illustrations of logic boards/main boards see pages 35, 39, 104 and 173.
Here is a power supply board.
Like this one, they typically have transformers, capacitors and heat sinks, all designed to handle large amounts of power and heat.
For information on power supply boards see pages 72, 104, 105, 166 and 172. For illustrations of power supply boards see pages 167, 173 and 174.
Mita 152 disassembly.
Here is some more disassembly.
On this machine, we are removing the operation panel, which involves removing the entire top cover. We then have to unplug the connectors to the operation panel.
Removing the exposure lamp is not as easy as it first seems. Even after unhooking it from its electrode, it will not go anywhere. It turns out we have to remove the thermofuse holder, which also is the electrode mount. That allows us to remove the lamp.
Note that this lamp has burn rings in it, and must be replaced.
Cooling fans sometimes turn too slowly as they get older, resulting in blown thermofuses, hot platen glass, etc. This is the case in analog copiers and is not likely to happen in digital machines. Usually, if you spin the squirrel cage fan by hand, it will spin for quite some time. This fan is suspicious, since when spun, it comes to a stop rather quickly. In some cases, the fan can be disassembled and the bushings cleaned to solve the problem.
Simulations
The simulation procedure on this machine (a Sharp) is similar but not identical to a previous machine that we worked on. On this machine, the technician presses, clear, pause, 0 and pause to get into simulation. Then, to calibrate developer, you would press 2, then 5, then print. This machine also requires you to adjust a potentiometer on the developer unit to achieve a flickering toner light on the display.
For information on simulations see page 114.
Scan simulation. By doing this simulation, we get the scanner to go back and forth.
Exposure lamp simulation. This turns on the exposure lamp.
Switch simulation. Many manufacturers call these inputs. The display shows us a list of switches and sensors in the machine. By reaching inside the machine, we can actuate the switch, look at the display and see if it shows the activity, as we are doing with the transport switch (the switch after the paper leaves the drum area).
Here is another machine, a Canon, with a completely different simulation procedure. On this machine, we have to cheat the front door interlock, which is a bit tricky. We then insert a 2mm hex key into the access hole for the service switch.
Ignore the flashing display. To the eye when filming, that was not flashing, but the camera apparently records the frequency of the LEDs differently than the human eye.
When the machine is in simulation (service mode) the display indicates [ 1 ]
We then entered a simulation which lights the entire display
Here is the aging mode.
In this mode, the machine goes through all the motions of making a copy without producing any: It scans, turns the feed tires, runs the drum, coronas, etc.
Here is a lens test mode.
Sharp 8570
Here are some routine procedures and items.
Removing the charge corona.
Removing the developer unit. We have to unlock it and shift the toner hopper away from it. It then slides out. Reinstalling is the reverse procedure.
The yellow item is the transfer/separator corona.
These are the separator corona fingers.
This fuser slides out. This is the machine that we did the complete fuser rebuild on.
That is a view of the drum.
Scan once print multiple
You may here the term SOPM. Here is what it means. Most digital copiers will scan the original once, keep it in memory and then print as many copies as requested from that memory. Here you see us do that. We select a quantity. The machine scans the original once and produces multiple copies from one scan. For the remainder of the copies, the scanner is not doing anything.
Document feeder
Originals initially touch a sensor, letting the machine know they are there. The pickup roller than pulls them in, one at a time, to a second roller, which carries them to the document feed belt. The belt carries the original document across the glass to the home position where it is scanned. In the case of digital copiers, there is usually no belt.
For information on document feeders see pages 27, 28, 114-116 and 128.
For illustrations of document feeders see pages 114, 116 and 128.
Collator
This collator receives the copies in this section, and then transports them down below, where individual bins and gates direct each copy to the appropriate bin. Collators are being phased out, since digital copiers stack jobs in order, rather than having to sort them one sheet at a time.
For information on collators see pages 115 and 117.
Duplex
Duplex activity begins at or immediately after the fuser unit. When the machine is in duplex mode this gate directs the papers from the fuser up and into the duplex area. They then come to a stop and feed back down to the duplex tray. They are carried in there and stacked, as if they were in a cassette. There are usually jogger rails and motors to keep them neatly stacked. They are then fed by a pickup roller to the copier registration roller. In the case of digital copiers, they are usually trayless. The copies, after being turned around at the fuser, are fed one by one directly under the machine and back to the registration roller for the 2nd side of the job, one sheet at a time.
For information on duplex see pages 113 and 115.
Scan: Here is a view of a scan motor, scan board and scan cable. This is rather typical. This is a stepping motor, which can run at various speeds to enlarge or reduce, as well as copying at 100%.
For information on scan cables, clutches, and motors see pages 28-33, 41-44, 78 and 99.
For illustrations of scan cables, clutches and motors see pages 32, 33 and 99.
This is a scan clutch. Inside you can see two solenoids. One engages a clutch to drive the scanner forward. At the end of scan, that disengages and another solenoid engages the scan return clutch. This particular clutch uses O-rings to engage the two plates of the clutch.
For illustrations of scan clutches see pages 32 and 99.
This is a scan clutch assembly from a reduction/enlargement copier. These are rather complicated mechanical devices. Within each unit, there are at least two clutches. One for scan and one for return scan. In the case of reduction/enlargement machine, there is also a mechanism to change the speed of scan. Typically, different sets of gears that mesh with the main driving gear. Disassembling these is rarely done, and it is rare to find any that are manufactured anymore. Nearly all machines, even those that do not have reduction/enlargement, now use stepping motors for scan.
Cleaning fax optics
Here is a thermal transfer fax machine. Cleaning optics on this is about the same as many other faxes, regardless of type; inkjet, laser or thermal.
Typically, you must remove the operation panel to get to the optics. This often involves pushing, squeezing and bending plastic parts. They sometimes break.
On this model, we must also remove the transfer ribbon.
Having removed the operation panel, we now must remove the inner cover. This is held on by screws and by plastic snaps that are not always obvious. You have to insert a screwdriver and push and pull until the cover pops off.
When the cover is off, you can clean mirrors, lens, CCD and slit glass, just as you would on a digital copier.
For an illustration of the Fax printer section see page 120.
For illustrations of the contact image sensor/contact sensor unit see pages 37 and 124.
For illustrations of the CCD see page 30, 36 and 123.
For an illustration of a thermal head see page 128.
For an illustration of a fax document feeder see page 128.
THE END
Copier
and Video Training Package