Xerox 5090/Docutech 135 Techinical Information
By Raymond Cote

     Over the past few months, I’ve received quite a few tips on repairs from the field, and I’d like to thank everyone for their input. I’ve compiled a list of most of the tips and would like to share them with you. Most of the technicians out in the field have some documentation at their disposal, and when they use it, it usually brings them to a logical conclusion. Some techs, on the other hand, are working with little or no documentation whatsoever. I hope that this information will help out in some way. Also, I encourage everyone in the field to purchase the latest field service manual from Xerox to make their lives a little easier. All documentation, by the way, can be purchased online at www.xerox.com.

Platen Glass Cleaning

     This may sound like a stupid topic to discuss, but as you read the following information about the platen glass, you’ll see how important it is to clean the platen properly and the problems you can cause if you don’t.

     A number of techs have expressed their concerns about cleaning the platen glass. Most Xerox-trained techs know that the platen glass is coated with a sensitive protective coating that is vulnerable to any commercial cleaning agent.  It’s strongly recommended that you not use commercial cleaning agents to clean the platen glass. However, improper cleaning agents are being used in the field to clean the glass surface. More customers are performing their own maintenance on their copiers, and it’s easy for them to pick up a jar of commercial glass cleaner and use it with the intention of cleaning the glass. What seems like a simple glass cleaner is actually degrading the magnesium fluoride coating on the platen glass, and when enough of the material is washed away, the results will be a stray light problem. A host of 09-xxx faults will result, and you may even experience several 05-xxx document handler problems as well.

     To avoid an early replacement of the platen glass and photoreceptor belt due to 09-xxx stray light system faults, follow these procedures when cleaning the glass. Xerox recommends using a soft cleaning cloth (35P3191) and a specific glass cleaner (43E140) that won’t leave any streaks. Or you can go to your local grocery store and purchase a bottle of vinegar-based glass cleaner. I’ve used the small (white) square cotton wipes used in the printing industry to apply the vinegar to the glass, and then I use a dry cotton wipe to remove the vinegar. When using any type of liquid on the glass, use a slightly damp cloth so that there are no accidents with the fluids getting into the optics cavity.

After the glass is cleaned, check the surface for any streaking because it will have an effect on the Dc-951 xerographic setup. The front cover (2K18462) on the document handler should be removed to gain access to the platen glass so that the bottom can be cleaned as well.  As a substitute for vinegar, use plain water (sparingly) on a very soft cloth. Actually, water is probably the best cleaner available because it contains no harsh chemicals and won’t destroy the protective coating on the platen glass. Antistatic fluids should never be used on the platen glass. These fluids will leave a thin film on the platen glass that will actually increase stray light and, thereby, cause the photoreceptor belt (1R88) to have an early end of life (09-203 and 09-204).  Have you ever wondered why the photoreceptor in certain machines won’t get past 400,000 impressions? Find out what the customer is using on the glass. Question the customer, and ask if they’ve been experiencing a lot of 09-xxx “stray light system faults.” My guess is they were using antistatic fluid on the platen glass to help the document handler work better. Makes sense, doesn’t it.  By the way, a new platen glass (90P411) sells for $294, and a new photoreceptor belt (1R88) sells for $365. Vinegar sells for about 95 cents.

Vertical Transport Ski Magnet Failures

     Many field techs have expressed concerns about the magnetic strips on trays 1 and 2 and the duplex tray. All copiers in this family share this problem. Transport skis separate from the magnetic strips as the adhesive dries out. Sometimes good commercial instant glue will repair the delamination of the ski and magnet until the ski is replaced. Carefully examine the assembly (while it is out of the machine) to see if the ski and its holder are free of any physical damage. If you notice that the ski is in good physical shape and the only thing that needs attention is the loose magnet, then repair the device and reinstall it in its proper location. As the ski wears, it will show signs of discoloration and possibly evidence of wear. As you examine it, take notice of any wrinkles or distortions in the ski. If you see something, then replace the ski.

     All too often, we troubleshoot a two-sided-copy jamming problem and overlook the ski assembly in each of the three tray positions. We sit on a box of paper with the doors open and the interlocks cheated to observe the machine in a print condition while watching the paper path, keeping in mind that the paper is feeding at 135 copies per minute and it’s sometimes quite difficult to see the actual problem. So, we sit there with a dumb look on our faces trying to figure out what the heck is wrong. The vertical transport belts (600K6991) and the vertical transport sensor (130K17476) have been recently replaced, and still we have this jamming problem. We closely examine the duplex ski assembly (30K53681) and note that the plastic strip has a small tear in it that is actually slowing the paper considerably when it exits the duplex tray. The random jamming problem goes away when we change the ski assembly.  On close examination of tray 1 ski (30K53691) assembly, we note that it’s discolored and deformed. Tray 2 ski assembly (30K53701) is in similar condition also. When all three assemblies are replaced, the 5690 runs nonstop.

     All too often with these two-sided-copy jams, we seem to tear the machine apart and replace parts that don’t need to be replaced to resolve the jamming issue. And while we’re on the subject, when was the last time you checked the drive/blower motor assembly? Now is a good time to check the assembly from the rear of the machine. Remove the rear panel, and open the access door to the rear of the tray area. Observe the O ring belt (23E741) while the copier is running. If you see that the belt is stretched, it will have excessive slop on the pulleys. The stretched belt slips on the drive pulley, causing jams in the paper feed of the duplex tray (not enough vacuum). After you replace the O ring belt, do the adjustment (ADJ 8.11), and the duplex tray will feed into the next century.

Dog-Ears Duplexing 12-, 13-, and 14-inch paper

     Ever have excessive skew or dog-ears while running duplex jobs with 12-, 13-, or 14-inch paper? As the paper leaves the duplex tray, it hits the vertical transport. It took a long time to realize, but the cause of the skew is because there are no guides in the 12-, 13-, or 14-inch area. The good news: there’s a retrofit that will fix this problem. If your customer uses a lot of these weird paper sizes, then order a duplex paper guide repair kit for your Docutech printer (family), kit number 600K34680. This advice is thanks to a tech in Maine that experienced the problem with a customer that ran 12-inch paper exclusively.

08-152 and 08-153 Paper Jams

     Thanks to a tech in eastern Los Angeles who tells us that after troubleshooting a paper feed problem, the RAP led him to replace the registration transport sensor assembly (130E342). Sounds simple, and the documentation worked perfectly. The problem was the customer needed the machine to work over the weekend, and it was a Friday, after 6 p.m. local time. Knowing his supplier was closed for the weekend, he decided to open the registration transport sensor assembly to see if it could be cleaned or repaired in some way. Using a scribe, he carefully removed the dust cover, and once the cover was removed, he was able to identify the problem. Paper lint was covering the sensor assembly to a point that it couldn’t function. After he blew out the dust, he replaced the cover and returned the sensor assembly to the registration assembly. On Monday morning, the sensor assembly was ordered through his regular vendor, and when the part arrived, it ended up on the parts shelf for another two months before the part was expensed.

Scratches on the Photoreceptor Belt

     A self-maintainer in Florida told me in an e-mail about a scratching problem that couldn’t be wiped off. After several photoreceptors were destroyed, he discovered that foreign material had somehow managed to get into the developer housing. My initial advice was to use the CQ-9-604 RAP in the service manual to isolate the cause of the scratches. It was determined that the developer was developing more than a latten image on the photoreceptor belt. He removed and disassembled the developer housing to investigate the problem. He removed all three developer rolls and closely inspected them. He noted that two bearings (13E3590) were close to failing; the third bearing was totally destroyed. Although the bearing was destroyed, it was still turning on the magnetic developer roller shaft and was heating up, causing the toner to melt and form little rocks that destroyed the new photoreceptors. While the developer housing was open, he examined the paddle wheel bearings (413W21052) and paddle wheel (600K17790). He determined that the trimmer bar (25E10) was razor sharp and needed to be replaced as well. While there, he noted that the mixing auger (94K850) and bearings (413W21054) were also in dire need of being replaced.

     It’s interesting to note that any bearing that heats up can cause the toner to melt and form rocks. Once rocks form, your photoreceptor belt is doomed. As a general practice, all bearings should be changed at 50 million copies. Magnetic developer rolls should have their bearings replaced at 15 million copy intervals. Don’t wait until you destroy a photoreceptor because of failed bearings. You can’t compare the cost of a few bearings to a new photoreceptor belt. External sources of contamination can be attributed to frayed drive or path belts, fuser agent, and fibers from static brushes or delamination of the photoreceptor belt itself.  Generally a “dump ‘n thump” will only hide the problem for a short time, and the problem will return. Bite the bullet on this one before you expense 20 photoreceptor belts. 

     If you rebuild a developer housing and replace all the bearings and the problem seems to come back, look at the way the supplies are stored. A technician in New York City told me that one of his customers stored his toner in a basement near a hot water heater. The storage room was not only dry, but also very hot. Due to the high temperature, the toner was hardening inside the container. They found that little rocks had formed inside the toner container before the toner even went into the toner hopper.

     Once again, thanks to all the techs that have sent in their suggestions and fixes for various problems they found in the field. If you have an unusual problem or experience something that is noteworthy, please send me the information, and I’ll pass it on to the field.