Optics on the Xerox 5090
When should you Paint the Optics?

By Raymond Cote

 Several techs have expressed an interest in learning more about the operation of the optics on the Xerox 5090 copier. I would like to share some technical information with the field concerning this area. Actually, if you are experiencing a host of unrelated “09-xxx” fault codes, most of them could be traced back to the Optics cavity.

 There are four major areas in the optics cavity that will be of concern to us:

--Document illumination

--Document glass and the lens position system

--Field stops

--System registration

 I would like to center my attention on the Optics cavity and the illumination of the document. The 5090 family copier utilizes a capacitive discharge type of system to illuminate the document on the glass. What that actually means is a high voltage has to be generated and somehow stored in a capacitor (somewhere) in the illumination power supply (IPS). When the proper time is at hand, the control logic sends a signal to the flash lamps, and the stored (high) voltage is discharged and the lamps illuminate the document (on the glass).

 In this issue we will look at the flash lamps and the reflectivity of the optics cavity in the 5090 family of copiers. As we are all aware, as the copier ages so do the flash lamps—and we all, at one point or another, have replaced the flash lamps (600K36540) due to aging or when the lamps are so old they will no longer give off the bright flash required to make copies. One of the tell tale symptoms the lamps are aging is the envelope of the flash lamps gets to be a milky color and the random 09-xxx system faults. Some system faults may be repetitive and some will only occur in random shutdowns. If you are experiencing random System faults, short flash lamp and Photoreceptor belt life we should examine the Optics cavity. If the interior of the cavity is starting to yellow or the white paint seems to be dull or dirty then it is time for a new coat of reflective paint to be applied.

 In most of the older 5090’s, you will notice the walls of the optic cavity have lost the high level of reflectiveness that is critical to operate the exposure system in a satisfactory way. What actually happens is the Illumination Power Supply (IPS) has to work harder to generate the higher voltage required to overcome the dull walls in the optics cavity. It actually will place a strain on the IPS and might result in an early failure of it (105K1056). The results will be shorter flash lamp life and possibly the life of the IPS and the Photoreceptor belt (1R88).

As a short-term quick fix, clean the optics cavity with Formula ‘A’ and a soft absorbent cloth. Be careful to protect the lens with several sheets of paper. Once the cavity is cleaned, select dc-904 and check the cavity sensor (ADJ 6.1) to see if the calibration is between 150 and 200. Make sure that Formula ‘A’ never touches the Photoreceptor belt, as it will cause deletions in the area that it touches. As a safety precaution, remove the Photoreceptor belt and place it in a safe dark place while washing the optics cavity. If the cavity reading is 200 and can’t be adjusted lower, it is time for new lamps and a good paint job.

 The 5090 optics cavity can be painted when it is necessary. A high reflective paint kit (600K36530) and application kit (60036520) is also available to accomplish this goal. It is recommended that you schedule this activity, because the cavity requires two coats and 24 hours’ dry time. The cavity must be prepared as follows: select reduction (165%) to allow the optics to adjust to the lowest position, thereby allowing you the space to remove the Cavity Bottom Panel (600K36550), the lower portion of the optics cavity. Power off the copier and remove the power cord. Remove the Platen Glass (90P411) and inspect it for abrasions (from the Document handler belts). If you discover that it has abrasions, replace the glass when you reassemble the optics.

 Remove the left and right flash lamp assemblies (113K842) and replace both flash lamps (600K36540) if the cooling tube (52E313) is damaged or discolored they must be replaced as well. (NOTE: This is critical—always use disposable gloves when touching the glass envelopes of the flash lamps. The oil from the hand will contaminate the lamp and cause it to explode in the tube. This usually happens a day or two after you install the lamps. It is a good practice to wash the lamps with film remover first, and then install the lamps. This way, even if someone else touched the lamps you will be protected.)

Next, remove both light shields (55K4312) and place them on a (paper covered) work area. Remove the cavity bottom panel by releasing the four quarter-turn screws and tilting the panel to one side to remove it, and place it on a clean work surface. Some technicians have successfully painted the light shields as long as they were not too badly burned or discolored. NOTE: If the light shields are burned or discolored beyond restoration, check the Optics cooling blowers (127P2347) to make sure they are both hooked up to the proper hose connections and that they are in fact blowing cool air into the flash tubes. (The blowers come on while in print mode.) Remove the Photoreceptor belt (1R88) and dispose of it. Cover the Photoreceptor module with heavy paper to prevent any contamination from the paint, and then close up the photoreceptor module assembly and close both doors. Remove the lower lens surround panel (55E3463) and the lens shield (55E12380) (NOTE—do not paint!), which sort of just sits on the lens. Cover the lens and the whole lower optics cavity with heavy paper or a drop cloth so that it dose not become contaminated with paint. You can see how far down the paint goes. Try to work neatly and clean up any spills or mistakes that occur.

 If you are budget concerned, you will be able to go to a well-supplied paint store for quality paint and application rollers. Xerox paint is an excellent paint with superior reflective qualities and longevity. However, there are several excellent quality paints on the market that will do just as good a job as the Xerox brand. My first use of a competitive paint was Behr Premium Plus Exterior Flat “Ultra Pure White,” number 4050. I have found that the paint (when applied according to directions) has a tough surface that has high reflective properties. The paint is mildew resistant and is 100 % acrylic latex. which makes for easy clean-up. I started my first optics cavity paint job at 8 a.m. and by noon it was ready for the second coat. The directions on the paint require 4 hours between coats.

After the second coat, it is advised that the copier be allowed to dry for 24 hours. If you started this job on a Friday, then on Monday the re-assembling of the optics cavity can be completed. The parts that were removed from the Optics cavity should all be individually painted, paying particular attention to the cavity bottom panel (600K36550) (sometimes referred to as the “wash tub”) and the black (felt) strip that circumvents the “wash tub.” From constant motion of the cavity optics, the wash tub (light) seal may become worn out or in some cases start to peel off causing “stray light” (09-361/2). If you notice the felt strip is loose, try an adhesive like Krazy Glue to restore the seal. If the seal is beyond repair, you can replace it from a store that sells sewing supplies; it’s just a strip of Velcro.

 On Monday morning, start by cleaning up the cavity area and removing the protective devices you used on Friday on everything. Start by installing the Lens Surround Panel (55E3463) and the lens shield (55E12380). Replacing the Cavity Bottom Panel (600K36550) is next, and then the two flash lamp Light Shields (55K4312) and Flash Lamp Holder assemblies (113K842), with the new flash lamps (600K36540) already installed. Slide in the glass (90P411) but do not yet secure the platen surround Front Cover (2K11371), because we will be adjusting the optics cavity sensor assembly later. Remove all the protective paper or drop cloths from the Photoreceptor module and install the new belt (1R88), and close up the assembly and both doors. Re-install the power cord to the 220-volt AC line and turn on the copier.

When you can enter DC-131, select MIM and location 169 and reset it to 100. (This is the address that tells the copier that you have new lamps installed) Reset the photoreceptor belt in DC-107; this also tells the copier you have installed a new Photoreceptor belt. Not only does it reset the counter but it also resets the on-board computer that controls the logic for the DSS—new belt, new patch, new charge requirements, etc.

 Use plenty of white paper on the platen glass, enter “DC-951” and select Preflash setup, and press start. You should get an “06-236” almost right away. That’s because we kept raising the “Cavity sensor” as the lamps aged. Now that we have new lamps installed we have to lower the setting on the cavity sensor. Check adjustment ADJ 6.1 in the adjustment section and adjust the cavity sensor assembly. Then return to DC-951 to adjust the Preflash. Run Preflash to its completion and then enter DC-951, and complete the Xerographic set-up using the test pattern 82E2770. Check paper tray 3 and ensure that you have at least four reams of paper loaded.

 The Independent Service Organizations I share information with, or ISOs, have had good results with non-Xerox, high-reflective good quality paint. Actually, the first paint to be recommended was Glidden 3400 white paint. It was successfully used by an end-user of a high-volume copy shop. His philosophy was simple: If it presents a problem, he will have to buy Xerox’s paint and then repaint the optics tub. Would it be double work? Maybe, but at least we were thinking outside of the box. At the very least, if we were not successful, then we would have to paint twice. By the way, the paint I used cost about $14 and the foam roller cost $ 2.49.