Problem 50 Service error
Source of trouble failing fuser
Resolution The fuser is the element that melts the toner onto the page. The basic principle of laser printing is this... a laser writes the image on the toner drum. The toner drum rolls through the toner and picks up toner where the laser hit it. The page is passed between the toner drum and a heating element (the corona wire) which is just warm enough to make the toner stick to the paper. The page is then passed through the fuser, which is hot enough to fully melt the toner and fuse it to the page. There are actually two important parts in that last step... one is the fuser, and the other is the DC voltage unit. These are important because the error 50 refers to a malfunctioning fuser, which can be caused either by a faulty fuser or bad electrical source. The fuser is a roller with a lamp in it (like a halogen lamp) providing the heat. There are two main power units in your printer, one is the DC converter, the other is the high voltage unit. Before tearing into the printer, turn it on and let it warm up, shut it off and open the printer. Does it get hot? If it doesn't, you most likely have a bad bulb. Do you live at the end of a long dirt road? Kidding, but that could do it. The fuser is located inside and toward the back of the printer. On an LJ III (which is, in my opinion, one of HP's greatest printers - half a million pages is not an uncommon number before needing any serious maintenance), open the top of the printer and remove the toner cartridge. The fuser is black and has a hinged top that opens. There will usually be a long, narrow brush inside the fuser that wipes it clean. The fuser is held down by four screws. Once extracted, the lamp is accessible by removing one of the end coverings. My recommendation is to start by replacing the lamp. You can get one at any of a number of parts places, such as http://www.pcss.com/. Alternatively, you could just buy a rebuilt fuser assembly. If this doesn't fix your problem, the problem may be that the fuser is getting insufficient power, and you may need to replace the AC power unit. This is the part that the cord actually plugs into... power comes out from it in DC current to the fan, high voltage unit, fuser, etc. To remove this you actually have to remove the cover... start with the fuser ( the most brittle part), and if that doesn't fix it, email me.
Problem Print is too light
Source of trouble Expired toner cartridge
Resolution How old is your cartridge? Did you know that exposure to UV lights can reduce the adhesion of toner dust? You may need a new cartridge. Begin by removing the toner cartridge and vigorously shaking it from side to side, then trying it again. If that doesn't work, check your high voltage setting (below). If that fails, get a new cartridge.
OR Incorrect high voltage setting
Resolution Look for a darkness setting - it may be in the menu system, but there might also be a lever or knob inside of the printer (check your owner's manual). HP conveniently colors these knobs and levers green. This switch regulates the amount of high voltage power that is sent to the laser and influnces the amount of toner that is attracted to the paper. Crank it up. If neither this or a new toner cartridge works, you may be having fuser problems, or need to get a new high voltage unit.
Toner cartridges Laser printers work like a self-cleaning oven, making it often difficult to spot the obvious source of the problem. However, if the printer is mechanically functioning correctly (paper feeds, toner gets onto the page, etc), then the problem is most often the cartridge. Usually, that is the first place to start. Also see the cleaning overview.
Problem Spots on the printed page
Source of trouble Toner Cartridge, waste bin full or paper path contaminated
Resolution Replace the cartridge - you can try to empty the waste bin yourself, but don't say I didn't warn you (messy). Using a Qtip, trace the paper route looking for toner globs - most commonly on the anti-static teeth next to the corona wires
Problem Streaks on the printed page in vertical lines
Source of trouble Toner Cartdridge drum contaminated or paper path contaminated
Resolution It is easy to determine if the toner drum is contaminated - remove the toner cartridge and open the drum shutter, revealing the green cylinder (toner drum). If any toner clings to the drum, there is contamination, and the toner cartridge must be replaced.
Problem Vertical blank stripes
Source of trouble If not drum contamination (above), laser path could be blocked Resolution There is a mirror on the top of the case that reflects the laser onto the toner cartridge. Open the printer, remove the cartridge, and press the latch on the door half way. This should reveal the mirror for inspection. Clean it if necessary using a can of compressed air or a Qtip and some window cleaner.
Problem Printing too light or characters too thin
Source of Trouble Insufficient voltage for proper toner transfer
Resolution Voltage adjustment necessary
Problem Paper Jam
Source of Trouble Bit of paper somewhere Someone has been yanking on the paper(?) Resolution Search the paper path - bits of paper are very commonly found within the fusing assembly
OR Paper sensor stuck
Resolution Paper sensors are usually little black levers that swing freely across the paper path. Get the service manual, if you can, to find all of them - you can count on at least three. The printer monitors the length of time it takes for the paper to travel along the paper path, and if a sensor is not tripped, the Paper Jam error occurs, and the printer stops. Go to each and flick them repeatedly to knock loose obstacles and ensure proper movement and use a can of compressed air to blow out dust.
OR Roller or separation pad fault
Clean paper feed area (below). If the rollers feel slick to your fingers, they may not be able to pick up paper. Rollers are best cleaned with just plain water.
Cleaning the Paper Feed Area
Paper is fed into the Laserjets via roller and separation pad. The roller is rubber, and the separation pad is usually cork - it is designed to separate one page from the rest in the stack. If the roller has paper or dust adhering to it, it will not feed the paper correctly. The roller can usually be felt by reaching into the paper tray bay (make sure the printer is off) it may have a flat spot that should be facing down when it is at rest. If you can run your fingers over it with no resistance, than it is probably too slick to work effectively. It should be cleaned with a diluting medium (just rubbing your finger on it won't do - skin oil will clog it up quickly). Water works well, and alcohol is OK for very old rollers (alcohol causes new and soft rollers to wear out more quickly). The cork separation pad may need to be scrubbed with a Qtip - if this is dirty it can also be the cause of multiple feeding.
Last Updated 12/2004