In the Docutech Family Frequently asked by Techs

By Raymond Cote

When I was quite young, I remember asking my father a question about a model airplane I was building. The propeller of the model needed to be shaped a certain way, and I was not quite sure how to finish the tip of the propeller. When I questioned him about the propeller, his response was, “What do you think?” The photograph on the box showed a model plane that had a running engine, and the tip of the propeller was impossible to determine. I went down to the basement and found one of my dad’s aviation mechanic books. After looking through the propeller section for a while and thinking it over, I came up with a solution, finished, and mounted the propeller on the model. I was extremely proud of myself for solving this problem. Afterwards, I apologized to my dad for asking him a stupid question, and his response to me was, “The only question that is stupid is the one you do not ask.” I can’t tell you how good it made me feel to hear that from my dad. As I got older, I was never afraid to ask questions, even if someone later told me, “That was a stupid question.” Because when that happens, there is always someone in the crowd that will approach you and tell you that they were thinking of asking the same question. 

Dicorotrons (125K1450)

Mark S, a technician from the greater Boston area, e-mailed me with a question about dicorotrons. Before asking the question, he was apologetic and almost unsure of whether or not he should ask the question. Dicorotrons, for the most part, will live for many millions of copies. Knowing when to change them is the sixty-four dollar question. Here is the way I look at Dicorotrons in general.  When you check the HSFI screen (09-820 - 09-821 – 09-829) Charge 1 Dicor, Charge 2 Dicor and Charge 0 Dicor, the recommended replacement is 3 million copies. That’s all well and fine when you are working for the manufacturer and your parts budget is on paper. What happens when you have to purchase Dicorotrons in the field? You pay exorbitant prices for the replacement parts. As a cost-cutting measure, I always inspect the Dicorotrons for contaminants or any damage to the core itself before replacing any Dicors. Remove the wire (48K56790) and clean the Dicor housing assembly. Don’t use a wet rag because the water will wash the special (DAG) coating that is applied to the inside of the housing assembly. What I have used in the past was a slightly moist (soft) cloth with Film Remover (8R27). Inspect the housing for badly worn (DAG) coating inside the housing and any damage to the Dicor. If the Dicor is in good condition, replace the Dicor wire assembly (48K56790) and install it into the processor. If the housing assembly is damaged in any way, or if the special black coating is worn or damaged, then it is time to replace the housing assembly with a fresh one (48K78750). Or if you are compelled to pay top dollar for a fresh chopped Dicor, order part number 125K1450.

The same thing goes for the white Dicors (125K1081)— look them over very carefully, clean them, and replace the Dicor wire assembly (48K56790).  Before replacing the wire, check the housing to see if they are bowed in any way. This is especially true for the Transfer Dicorotron assembly because the transfer blade might not work properly or cause a copy quality issue. In some instances, it may even give you false 09-201’s.

Meanwhile, Mark was rolling with the punches as he was having an ongoing “Ozone” problem and was constantly replacing photoreceptors (1R88). He was under the impression that if he cleaned the Dicors on a regular basis, he would eliminate the Ozone problem.  About three weeks later, Mark called me and told me of the Ozone contamination problem and that washing and replacing the Dicor wire did not resolve the problem. He told me that he replaced a truckload of parts and e-mailed me a laundry list of parts that were in the photoreceptor vicinity and in the Xerographic process area.  Sure enough, the laundry list of parts was extensive and perhaps overdone to a point where it cost him a bundle. Once the Preclean Dicorotron becomes contaminated with Ozone, it is impossible to clean the Dicor housing.  You can call the local fire department and hose the Preclean Dicor for ten hours and never wash out the contaminant from Ozone gas. Somehow, and I don’t know why, the plastic absorbs the gas when a Dicor becomes contaminated with Ozone, and it is irreparable. When I see an Ozone contamination problem, I replace all six Dicors in the Docutech along with the photoreceptor belt and brush (4R57).  Needless to say, the cost of replacing all six Dicors was a deciding factor for Mark. At $125.00 each for the Dicors, cleaning and re-wiring them seemed like the cheapest and quickest way out. 

If you are at all curious as to what DAG stands for, it means Dimetreous Aqueous Graphite.  That’s the black stuff on the inside of the Dicorotron housing assemblies.  The material is actually a water-based paint that is supposed to keep the resistance of the Dicorotron shield and housing assembly very high. It is strongly recommended that you should never wash the Dicorotron housing assembly. Any liquid seems to wash the DAG coating thin. When the DAG coating is washed away, the electrons go off in unexpected ways, and the Dicor will become useless. When you notice the DAG coating is getting thin, it’s time to replace the Housing assembly.  For the stupid question department: e-mail me at VillageCopierNY@AOL.COM and I will probably come up with an equally stupid answer.  Hey, at least you will feel better for taking the challenge and asking.

Some new competitive (non-X brand) toner-waste containers are causing problems in the field with toner-waste container error messages.  When you examine the box, the waste container that comes with it looks like the original Xerox® package, and you assume it’s from the manufacturer.  The problem occurs when you change the waste container, and the error message does not go away.  That’s when you dive into the machine and virtually trace out all the wires in that circuit only to discover that there is nothing wrong with the circuit. The problem is that the plastic is so thick that the sensor assembly can’t see itself and the processor thinks the waste container is still full.  Some say the containers are more “opaque”, “darker in color” or just “thicker material is used”. I think at this point in time, you have two choices: Get on the phone and call the supplier of the waste containers and demand that they send you a new batch of genuine Xerox® waste containers. Or, you can get a razor blade and cut a window on both sides of the waste container (where the sensor assembly sees itself). The window should be about 3 inches high and wide and then sealed with the widest clear tape you can find to seal the waste container. Case closed. 

It’s funny in a way because the first time I saw this problem, the key operator was the one who got me out of the jam. Up to this point, I had never seen anyone (successfully) open the waste out of a container, dump it, and then reuse it in the machine. I didn’t think it was possible to do so. Actually it was not feasible to do because the waste containers were free to Xerox® customers when they purchased the toner. There was never a need to empty the waste containers; just pick up the phone and get them (Xerox®) to send you some more free containers. As I became more experienced in the Xerox® Docutech®, my mind started to work like lightning. One brilliant flash and it’s gone.

Fuser Wraps and Jams

The only time the world beats a path to your door is when you are in the bathroom.  Or it just seems that way when you start getting calls for fuser wraps. What is disturbing about fuser wraps is that no matter what you do, they never seem to go away.  If you are having a lot of fuser jams, first check your HSFI screen and replace all the HFSI’s that are due in the fuser module.

HSFI    DESCRIPTION                                   PART NUMBER        

10-801 Metering Blade Assembly                    33E1110         

10-802 Fuser Wick Assembly                            94E680           

10-802 Fuser Agent Filter Assembly                 600K20330    

10-803 Donor Roller Assembly                         22K27670      

10-804 Fuser Idler Gear           7                      K120

10-804 Fuser Drive Gear Assembly                  7K1700          

10-805 Sensor Assembly                                  Q1009, Q1010         Clean sensor assembly           

10-806 Pressure Roller Assembly                     22K6941        

10-806 Fuser Stripper Fingers (3)                     10S21202       

10-811 Pre Fuser Transport Belt Kit                 600K8320      

10-812 Metering Roller assembly                     22K9161        

10-813 Decurler Belt Kit                                   600S7013       

10-814 Metering Assembly 

(also known as RAM assembly)                                                       Clean (change the oil)

10-815 Prefuser Transport assembly                                               Clean belts &  vacuum holes   

(As needed) Fuser Heat Roller Assembly           22K53280      

When a new customer comes aboard and a problem is noticed, I try to stick to the rules of engagement by entering diagnostics and performing the HSFI’s that are due. If the HFSI’s do not fix the problem, I will overhaul the fuser area with all the above parts just to have a starting point.  The starting point may be difficult to find when you do not know the machine’s history or where the previous technician left the machine. If he was a good record keeper, you should be able to see the parts that were installed (approximately) by looking at the logbook and the total meter.   It’s sometimes difficult to detect new parts, especially if the technician did not reset the HSFI counter. When in doubt, throw it out and install new parts, then reset the HSFI counter yourself. Hey, at least you will know where you are when it comes to the fuser area. As a general rule, replacing the HSFI parts (when they are due) will usually resolve most of the problems.  And then you can return the machine to the customer. If fuser wraps continue, then sit down, put your head between your legs, and kiss your butt goodbye. All kidding aside, nothing beats pushing the printer down an elevator shaft. When you get out on bail, check the following: Fuser Air Knife Manifold and Fuser Roll Clearance Adjustment (ADJ 10.12). If the book is not handy, use 8 sheets of 20-pound paper to make the adjustment (11 sheets when the fuser roller is cold).  Make sure the wick and blade have been replaced and (very) closely examine the heat roller assembly. If it’s worn or discolored, replace the Fuser Heat Roller; they do fail in the weirdest ways. You can scratch your head looking at a heat roller and not know it’s bad. While the machine is running paper, open the left hand (12 inch) door and observe the puffer air pressure— it should be between 19 and 25 pounds. If not, then adjust the air pressure with the handy valve on the air gauge.

Note: if the air pressure is too high (35 to 40 pounds), you may experience jams and or copy quality problems related to fusing. Remove the Prefuser transport and clean the transport belts and make sure the vacuum holes are free of debris. Rotate the Prefuser belts as you are cleaning them and make sure that none of the belts are damaged in any way.  Make sure that the belts have a texture to them and are not smooth. Clean the Fuser baffle as well while you are in this area.  When I remove the Prefuser Transport from the printer, I always check the little holes and make sure they are free of any toner or contaminant. In DC 330, select print run and physically check to see if the vacuum motor on the Prefuser transport is actually turning and there is vacuum on the transport itself. While in DC 330, check the Prefuser sensor by blocking it with paper, then try to wiggle the sensor assembly. Hey, a loose wire or sensor could make your life miserable. 

Check all the sensors in the fuser area by jiggling the wire harness of each sensor assembly. Check the fuser exit sensor as well by (rapidly) toggling the actuator. Keep an eye on the screen to make sure the flag goes high and low as you toggle the sensor.  Re-coated heat rollers can sometimes be defective after only 500,000 impressions and are rendered useless. Hey, so much for cutting cost—you have to live with the heartaches.  While the fuser module is out, check the anti-static brush. Due to the fuser vapors, the brush will accumulate toner and will build up all kinds of gunk on it. When you see this condition, use some film remover on a rag and remove the build up material from the brush. Also note here: the brush should never actually touch the Pressure Roller— there should always be a small gap between the brush and the Roller.

As the fleet of Docutechs gets older, you will find more air leaks from dry and/or cracked hose or loose fittings.  While running the printer, keep an extra eye on the air gauge  (as if you have an extra eye) as paper goes through the fuser assembly, and make sure the air knife (deflection)  release pressure is about one (1) to two (2) pounds of air.  If you are not getting the release pressure, there might be a leaky air hose or a clogged up (air) moister filter. On the other hand, if you notice the air gauge is oscillating like a banshee, then you will have to troubleshoot for that leaking hose. Also, while the printer is running paper through the fuser area, keep an eye on the gauge (don’t blink). If you see the gauge hesitate for a split second when the jam occurs, replace the puffer solenoid assembly (121K5500). Never try to take the solenoid apart to fix it; it won’t work. Field engineers have taken them apart and played with them for hours on end with no success. 

While in the fuser area, look at the fuser heat roller and try to determine if the Heat Roller is dry.  If it’s excessively dry, try this: look in the trash container for an empty soft drink can. Find a set of scissors and cut two (2) strips about half an inch wide by one inch long.  Carefully wrap the guide pins for the RAM Assembly with the tin can (material). Then slide the RAM into the operating position. Run the printer and watch the oil dispense on the Heat Roller assembly. If you have more oil on the Heat Roller, then it’s time to replace the RAM Assembly (PL3-D10, 48K27290).

And you thought that fuser wraps would be easy? After you have replaced that laundry list of parts I mentioned, and the problem is still there, start checking the check valves in the finisher. The first check valve (53E831) is on the airline from the processor to the finisher (PL9-D1). The second check valve is near the finisher compressor assembly (PL9-D8). The check valves are never taken into consideration until we start to pull our hair out of our heads in frustration.  Make sure the “Ground Strap” 117K11010 is connected properly and is in contact with the Fuser Metering Roller Bearing assembly and the Metering assembly.  Check the Metering Roller Assembly (if not new) to see if it is smooth. It’s like teeth in a hen, you really can’t see it until you remove it from the Metering assembly and hold it close to natural light to see if it has a slight texture to it.  Think about this: When the Metering Roller assembly gets old, it gets smooth and doesn’t carry the fuser agent to the Donor Roller properly. If you are in doubt about the Metering Roller assembly, drop back 10 yards and punt (replace it). Check the fuser agent. Does the customer have some (really) old fuser shield (blue plastic bottles)?  Xerox®, by it’s own admission, has said Fuser Shield in the blue plastic bottles is defective and should never be used. It will increase jamming in the fuser area and drive you nuts.

On numerous occasions, we have found that the air line (53E1300) from the MIM compressor to the fuser roll-up cable is defective. When in diagnostics (fuser drawer open and cheated), operating the fuser solenoid the system checked out fine. With the drawer out, the hose must have been held together minimizing the air loss. When the fuser drawer is closed (in the home position), the crack in the hose was wide open. Funny thing is, we can’t see inside the plastic housing that hides the hose and wiring to the metering assembly. Only if we had x-ray vision……. Three hands and two more eyes….. Then we would walk on water all the time.

My thanks to Midwest Danny for many tips on fuser wraps.