Jardine Electronic Services
The Ole Tekkie's Printer Page

formerly The I.E.S.G. - UCB Laser Printer Repair Facility

images/cory.gif (125728 bytes) UCB's Cory Hall, home of the EECS Department 

Laser Printer Troubleshooting Notes 

Misc fixit aids from various sources. WAS constantly being updated.   This site was formerly at UC Berkeley

September 2002 update.  Howdy!  I was really surprised today, reviewing my access stats during a major re-work of my site, to discover that I was getting a lot of hits on this page that I assumed was dead.  This is a first cut at getting it cleaned up, but I must tell you that the last printer I worked on was my own LW II which had died and there I was swapping out parts and I even drove back to my old workplace in Berkeley to try it there.  Then the big question hit me:  "Are you still in the printer repair business or are you back to designing microprocessor- based data collection systems?"  So I went home, went on line to Circuit City and bought an HP Scanner/Copier/Printer for $300, and picked it up the next morning.  This was in mid-2000, and I haven't touched it, nor had any problems, except changing seven black and two color cartridges.  Think about this before you continue reading below about how to resuscitate some old kludgy printer! 


stop update 9/26/02 - check back and hit Reload on your next visit


A note to people reading this from around the world: this collection began as simply a list to help me remember from one repair to another just what I did to fix the last one.  As I had compiled it in a UNIX environment I could access it by logging in from someone else's terminal and review the notes.  Then came the Internet and these were my first HTML pages: a few tags followed by <pre> for the pre-formatted UNIX stuff and zap! I was on-line.  Then I experimented by listing the pages with a couple of search engines and now I get some 50+ e-mailed questions per year.

Well, needless to say I try to answer all of them, but it is not part of my (paying) job, so I had to sneak them in between jobs, at breaks, at lunch and even from my home connection.  I hope to have an afternoon where I can take all of this correspondence (yes, I saved it all!) and turn it into my FAQ, so keep tuned to this station.

Also credit needs to be given here to the people who taught - and are still teaching - me about laser printers: our boss, Ferenc Kovac and the real printer ace: Tho Nguyen.


Some useful URL's:

A few comments on stocking replacement parts.  Laser printer parts failures follow the same "bathtub curve" as the semiconductor failure curves: a few major parts break in the first period of use and then a relatively long period with almost trouble-free operation, and finally consistent trouble with dying parts.  What happens with the cost of laser printer parts is that they go down as the need for them increases, due to higher levels of production and competition from third party (non-OEM) suppliers.  If you base your purchase of spare parts on the history of previous printers and try to anticipate the failure problems on your newer printers you can end up with an excess inventory which also cost much more that it should have.  The parts suppliers above can meet most of your needs with off-the-shelf inventory.

An old saw from the production segment of industry:  you can't eat inventory!

Cheers and happy repair work!

Jim Jardine
Jardine Electronics (formerly at) U.C. Berkeley


Jim's Repair Notes Collection ('way overdue for updating) 

Greatest trick since powdered milk I discovered that many pickup and moving rollers develop a glaze, or are simply smoothed down by the abrasive action of the paper. On printers that are relatively new these parts can be made to operate either until new parts arrive or in some cases for thousands of copies more. For a while we were using ~180 grit sandpaper until one of our comrades suggested an emery board. Now we carry a length of ~2" in our wallets. This, plus the Swiss Army Officers' Champion model resting along side the wallet in a back pocket, can facilitate many on-the-spot repairs.

General advice from HP: - black streaks: dirty corona wire inside toner cartridge - vertical registration off on all but first sheet: sticky solenoid pad - re-occurring marks on paper: toner cartridge roller defect - toner smudging: dirty teeth or usually dry paper - blank spots: damp paper - gray background on envelopes: a dry atmosphere=static=background noise. Try setting density dial to 1. - paper curl solutions: flip paper stack load with arrow on paper package to side to be printed first store paper in flat, dry and not-too-cold area keep paper wrapped until ready to use. Rec. type is Xerox 4020 

Additional discoveries: - white line in output: dirt on corona wire or materiel in the 'teeth' - blown thermal fuse in Si series fusing assemblies: this unit consists of a normally closed switch. A ceramic rod is set above the switch and just below the convex shape of the steel plate which makes contact with the fusing roller. When the unit overheats the steel plate snaps to concave, putting pressure on the switch. The trick is to get the steel plate to return to its convex shape. We tried cooling, strong magnets and other useless experiments and finally came up with this: place in freezer ~1/2 hour and strike the aluminum holding ring against a flat surface. It must be struck with the steel plate facing in the direction of the striking movement, without hitting the plate (else it will snap back to concave!) 

Machine specific: 5Si & 5Si-MX (WX) - toner spills and jams and/or paper curling. On two of our brand new MX's we have had the new HP toner cartridges dump toner inside the machines, which subsequently baked solid in two locations: the entry to the FRA and on the small tfe rollers at the FRA exit. You can scrape the buildup from the entry (be careful you don't hit the roller and scratch it!) and this will eliminate jamming. The wrinkling is caused by the small roller retarding the paper on one side as it goes thru the FRA...well, it looks that way to me! And cleaning the toner buildup from the rollers makes the problem go away, so there you are. 6/98 note: after a couple of cleanings the shafts which hold the rollers break off. Rollers are part of the separation guide and are under WX engine. To get the FRA out just open the back, snap the two blue levers down, lift the assembly ~1/2" and remove. The entry buildup is usually on the right side. To get to the small rollers, remove a single bowed e-ring in the center of the exit roller assembly, slide it to the right and then the two chrome- plated flat springs are holding the small tfe rollers and can be removed with a single screw. I used my Swiss Army knife for the whole operation. Suggestion: only use your fingernails or a non-sharp plastic scraper to remove baked toner from tfe or tfe-coated (e.g.: fusing roller) parts. Even small scratches will allow toner to adhere faster when returned to service. 

IIISi & 4Si (NX) - hollow print on high usage machines: HP would like you to put in one of their $300 maintenance kits every 200K copies so they turn on the USER MAINTENANCE message which gets everyone upset as they think the machine is off-line, etc. After buying one kit and finding most of the replaced parts still usable I began to buy only those parts which were worn and fixed them as required. The one part that can sneak up on you is the transfer roller. It takes the place of the high voltage corona wire in the II's & III's. When it gets contaminated it can no longer carry the high voltage and hollow print begins to occur. I believe this is a time/heat related phenomenon as I have seen it on older machine with <200K copies and newer units with>600K copies. - smudging or 'offset' printing. This appears as faint printing on clear portions of the paper and always appears in the same area. On removal of the FRA a built-up area of toner can be found. After letting the assembly cool down (the fusing roller on these models has 1/4" Al tube wall and can hold heat for some time.) I have used isopropanol and my thumbnail to remove the buildup (see "Suggestion:", below), followed by cleaning with more alcohol on a Kimwipe or other tissue. The problem is that this works on some units and not on others. We are still trying to find the problem with a 4Si which persists in having toner buildup even after changing fusing rollers. Our current attempt at fixing is to change the fusing lamp to eliminate the possibility of a hot spot. - fusing assembly idler gear: as the II & III series have their famous 14-tooth gear that always freezes up from the heat of the lamp, the III & 4Si's have an 18-tooth idler gear (p/n RS5-0059) which wears out on the inside. I don't know what the cause is, but the symptoms are a lot of noise in the printer but operation seems OK. Eventually the gear gets bad enough that it lifts up and begins to skip contact with the fusing roller drive gear, causing jams. Our gears became worn at somewhere in the 750K copies range so replacing the gear automatically with a fusing roller change at anywhere over 500K copies is probably a good idea. Of course oiling on a regular basis might prevent the wear to start with. - 4si: error message 18 MIO other than those given in the book: network down, usually cleared by resetting 

4 and 5/M/+, 860, 1260, etc (EX) - wrinkle, curl or accordion fold at exit. We have found that an early (i.e.: <30K copies) cause for this to be an accumulation of dirt on the II, III & -D's (SX) - soft rattle during paper movement : worn 14-tooth gear in FRA - paper jam w/ loud rattle: frozen 14-tooth gear - hum and vibration during paper movement with apparent gear jamming/ stopping: bad motor, loose or bad motor connector. - skewed image on 1st page: still trying to solve! - first page ok, following pages have horizontal offset: sticky pads on clutch solenoids. - SERVICE 50 or 2 flashing red LED's: (first check continuity of fusing lamp, if ok, then) with the printer cover up, hold down the cover sense switch, the toner sensors (2) and the fusing assembly lever and turn on the printer. This should cause the fusing lamp to come on for ~3 seconds and then turn off. Continue holding everything on and after the warmup period (~2 minutes) the printer should try to print the startup page (Apple), during which the fusing lamp should stay on for at least 5 seconds. If the lamp does not come on the power SCR in the AC module is bad or flaky and should be replaced. This part has a Mitsubishi logo on it but it is carried by Newark under the Powerex brand: Newark # Manuf p/n Cost 03T BCR8PM-12L POWEREX BCR8PM-12L U$S 2.48 IIP (incl 

DEC 1100) - curls paper: bad rollers on face-down delivery ass'y - fan folds paper as it outputs:" " " " " - paper jam msg before motor starts: broken wire in door harness also check the paper sensor above the toner cartridge for dirt and/or improper operation (connects to DC controller thru density PCA.) - paper fan folds before toner: broken drum drive gear - paper sticks on input and reports jam: worn (slick) separation pad You can rough up the surface of these pads to get a little more service: at least until a new part arrives. Try a 100-200 grit sandpaper. 

Desk Jets - We had no repairs at UC Berkeley of HP Desk Jets, altho we worked on a few. However, due to this site being found by outsiders I received a Desk Jet inquiry, and I owned one myself, so we were able to resolve the problem by e-mail: - A few lines or even a page of normal print and the printed material stops, while the printer continues to spew paper and go thru all of its normal gyrations. Remove the ink cartridge and gently clean the contacts inside the cavity as well as those on the cartridge using a Q tip and alcohol. Using a bright light also check for corrosion on the cavity contacts. These are gold- plated contacts so treat them gently. 

For this fix I received a printerfield promotion from Guru to Wizard. :-)


HP tech service locator: 800-243-9816

Back to JES home page

To Jim's Page


Copyright (C) Jardine Electronic Services 1999-2006
Last updated Sunday, November 05, 2006 . Comments or questions?