HP 4200/4300 Swing Plate Problem

                                 HP 42XX/43XX SWING PLATE PROBLEM

     The HP 4200/4300 series of printers were a very good replacement for the HP 4000 and HP 4100 product line. Faster print speeds of 35 pages per minute for the 4200 and 45 pages per minute for the 4300 model. The 4250 providing 45 pages per minute and the 4350 cranking out 55 pages per minute on letter sized paper all using the same basic print engine. Overall a strong well built print engine. There are a lot parts that are not common to each model such as the fuser, paper pickup assemblies, laser scanner, drive assemblies and motors. There are some parts that are common to each model such as the paper delivery assembly, paper pick and feed rollers, feed assembly (paper transport) and the swing plate assembly. The failure of this part is common to all models and it will fail at some point. It’s not just the number of pages that determine when it will fail. If the printer does a lot of larger sized print jobs, such as 300 pages it will last longer than a printer that just does 10 page print jobs. The starting and restarting of the drive assembly and fuser takes it toll on the swing plate gears. When testing a replacement fuser sleeve on a 4200 printer in which 250,000 pages were ran though the printer using a 500 page print job, the swing plate looked almost new when it was removed from the test printer. It had been replaced before the test was started. On the other hand printers with only 100,000 pages or even less experience the swing plate failing. So how the printer is used will influence how long the swing plate will last. It’s not just a page count factor like a maintenance kit.

     The swing plate assembly is located in the left side of the printer if you are looking at it from the back. It’s just a metal bracket with 2 gears and a small spring to hold the tension on the gears. The swing plate connects the main drive to the fuser unit. The rear gear on the swing plate meshes with the 40 tooth gear on the fuser causing the fuser to turn. As the teeth on the gears start to wear down they will begin to make noise. The rear gear of the swing plate wears down first. There are two things that start to happen. The first of course is the grinding of the gears as they no longer mesh properly. The printer is still able to feed paper through the printer without jamming. The second problem is actually jamming most likely as it reaches the fuser as the fuser is no longer turning. If you have gotten to this point the printer has given you plenty of warning of the impending failure. Remove the face up tray and then the fuser by pinching the blue holding clips on each side of the fuser. Check that these retaining clips are not broken. If the fuser is not snapped securely into place it can exhibit the same symptoms as a bad swing plate gear assembly. Once the fuser is removed you can see the rear gear of the swing plate. As the teeth wear down they get sharper as the plastic is eaten away. You might notice a pile of what looks like paper dust under the gear. This is actually plastic dust from the inside swing plate gear and possibly the fuser gear as well. You can inspect the fuser gear for wear.  The rear or black gear can be removed as well by removing the formatter and accessing a hole in the frame to loosen the screw that holds the rear gear in place. Once this is removed you will be able to inspect the inner gear of the swing plate. There are some instances where just replacing the rear gear will bring the printer back temporarily, to a usable state. It’s best to replace the whole unit while you are there for smoother operation of the printer.

     Removing the swing plate for the first time will require some time to be completed.

The top, left and right covers will need to be removed. The fan and environmental sensor connectors will need to removed from the power supply on the left side. The formatter cage and right side cassette guides. The power supply is next. Make sure to have all the cables from the power supply to the DC controller routed into the center of the printer before removing. The power supply should slide out fairly easily. If it doesn’t do not keep pulling on it, most likely there is still a cable connected. The power switch actuator bar will need to be removed as well. This can only be removed after the lower cassette guide is out of the way. Once the power supply is removed you can actually see the swing plate assembly. The cable guide or shield, which helps to protect the cables that come through from the inside of the printer, will need to be removed at this point. Next remove the gear that connects the swing plate to the main drive, inspect and clean it while it is out of the printer. There are 3 screws that hold it in place and are easier to remove if you turn the printer on its side. Trace around the swing plate on the frame before you remove it. It wont be seen when the printer is re-assembled. This will help when installing the replacement. The black headed screws will strip very easily so use a screwdriver with a good tip. If the screws are giving you trouble, try and tighten a bit to break the seal. If you are having trouble getting it out you can remove the cartridge guide, which sits right over the swing plate. A spring hook tool is very helpful in moving the captive spring that holds it in place. Remove the old swing plate and install the new one. At this point be sure that the cartridge lock lever is in the down position, simulating the toner access cover being closed. If the new swing plate is installed with the lever in the up position the toner access cover will not close!!! I have also seen some instance’s where the new swing plate will not go back into the hole. The old one drops right in with no struggle. If you encounter this just swap the new gears and spring to the old frame. Reinstall the cartridge guide at this point. Take your time and reverse the dis-assembly process. The HP 4345MFP has the same setup as far as the swing plate goes. This model is based on the same print engine but has more bells and whistles so the replacement is much more involved.