Remanufacturing the Okidata B4545 Cartridge
- By Mike Josiah
- Nov 01, 2009
The Okidata B-4545 MFP printers were introduced in January 2008. They are based on a 21-ppm, 600-dpi engine. The toner cartridge lists for $169 and is rated for 6,000 pages; the drum unit is rated for 20,000 pages. They are nice simple cartridges and with list pricing at $170, very profitable to do.
These machines use the next generation of cartridge chips. Instead of a chip attached to the cartridge, they use a smart card type chip that is installed by the user into the machine. There is a slot on the machine just under the LCD display that houses the card. The card must be replaced each cycle. New replacement cards are available.
The cartridges used in this printer are:
It has been a while since the theory of a two-cartridge monochrome system has been covered so we have included it here. The drum charging system used here is rather unique, as is the toner developer roller.
The toner cartridge printing process is best explained as a series of steps or stages.
In the first stage, the drum charge brush and the pre-charge film both place a charge on the OPC drum. The pre-charge film starts the process off by placing a preliminary charge on the drum, which increases the efficiency of the charge brush. See Figure 1.
In the second stage, the laser beam is fired onto a rotating mirror (called the scanner). As the mirror rotates, the beam reflects into a set of focusing lens. The beam then strikes the OPC’s surface, leaving a latent electrostatic image on the drum. See Figures 2 and 3.
The third stage (developing stage) is where the toner image is developed on the drum by the developing section (or supply chamber), which contains the toner particles. The toner is held to the developer roller sleeve by a DC bias voltage supplied by the high-voltage power supply. The developer roller consists of a rubber-type roller with a separate resin conductive sleeve that fits around it. This DC-bias voltage is controlled by the printer’s intensity setting and causes either more or less toner to be attracted to the drum. This in turn will either increase or decrease the print density. Both the charge brush and developer roller DC-bias voltages are controlled by the printer’s intensity setting. The amount of toner on the magnetic roller sleeve is controlled by a double doctor blade system. This system has the first blade use pressure to keep the coating of toner on the developer roller sleeve constant. The second blade has a DC-bias voltage, which charges the toner. See Figures 4 and 5.
As the laser exposed areas of the OPC drum approach the developer roller, the toner particles are attracted to the drum's surface due to the opposite voltage potentials of the toner, and laser exposed surface of the OPC drum. See Figure 6.
In the fourth stage (transfer stage) the toner image is then transferred to the paper as it passes below the drum by the transfer charge roller, which places a positive charge on the back of the paper. This positive charge causes the negatively-charged toner on the drum’s surface to be attracted to the page. The small diameter of the drum, combined with the stiffness of the paper, causes the paper to peel away from the drum. See Figure 6.
In the fifth stage (separation stage) the paper separates from the drum. The static charge eliminator (called the “charge neutralizing needle” here) weakens the attractive forces between the negatively charged drum surface, and the positively-charged paper. This prevents toner dropouts onto the paper at low temperatures and humidity and also prevents paper from wrapping around the drum. See Figure 6.
In the sixth stage (fusing stage) the image is then fused on to the paper by the fuser assembly, which is comprised of the upper and lower fuser rollers. The paper passes between a heated ceramic fusing element and a soft lower rubber roller that presses the page up into the upper heating element. The upper heated element then melts the toner into the paper. See Figure 7.
In the seventh stage (drum cleaning stage) the OPC drum is cleaned. These cartridges are considered to have a 100 percent transfer system. As such they have a dust remover brush in the drum unit, but not a waste chamber.
The chip on these cartridges has a few functions. It detects a new cartridge when it is first installed, detects the cartridge is properly positioned in the printer, and of course monitors toner low and toner out. See Figure 8.
Figure 9 shows how the toner and drum cartridges fit together.
1) Remove the fill plug on the end of the cartridge. Dump the old toner out and discard. Vacuum the outside of the housing and the developer roller. Turn the developer roller a few times to vacuum all sides of the roller. See Figure 10.
Although we don't recommend it, once clean, you can fill the cartridge, install the plug and you’re done! We don't recommend this way because the doctor blade needs to be cleaned each cycle. Failure to do this will allow toner to build up on the blade causing vertical streaks, and eventually a ruined developer roller. The best way is as follows:
2) To fully clean this cartridge, the developer roller must be removed.
3) Remove both springs from each side of the developer roller. See Figures 11 and 12.
4) Remove the blue-colored bushing from the left side. See Figure 13.
5) Remove the pink bushing from the right side. See Figure 14.
6) Remove the developer roller. See Figure 15.
7) Remove the two screws from the doctor blade. See Figure 16.
8) Remove the doctor blade. Carefully separate the foam seal from underneath the blade. Be careful not to tear this foam as the cartridge will leak. See Figure 17.
9) Clean any remaining toner dust from the hopper and seals. See Figure 18.
10) Clean the doctor blade with a cotton swab and a small amount of acetone. Remove any remaining residue with another cotton swab and 99 percent isopropyl alcohol. See Figure 19.
11) Align the foam seal onto the small plastic posts on the hopper. See Figure 20.
12) Install the doctor blade and two screws. Make sure the contact leaf spring is touching the back side of the blade. See Figures 21 and 22.
13) Clean the developer roller sleeve with a lint-free cotton cloth, and place aside.
14) Install the developer roller gear side to the left. Make sure the clear spacers have the flat side down and that they are not crimped. See Figures 23 and 24.
15) Install the pink bushing on the right side of the developer roller. The clear plastic band should be over the arm of the bushing. See Figures 25 and 26.
16) Install the blue spacer on to the left side of the developer roller. The clear plastic band should be over the arm of the bushing. See Figure 27.
17) Install the small springs on both sides of the developer roller. The clear plastic band should be under the bushing. See Figures 28 and 29.
18) Fill the cartridge with B4545 toner. See Figure 30.
19) Install the developer roller cover. The fingers of the cover snap around the colored developer roller bushings. See Figure 31.
20) When packaging the cartridge, do not forget to include a new smart card. The printer will not accept the cartridge as new without one. The card is to be installed by the end user, and the slot is located just under the LCD display on the printer. See Figures 32 and 33.
Image defect chart:
Image defect charts are a good tool to help narrow down a problem that is causing an image defect. For this chart to work, the defects must be in line with one another. In other words the second and/or third marks must be in a straight line from the first. Measure the distance from the first to the second marks in and refer to the chart to see what parts may be causing the issue.
50.6mm Transfer roller
51.8mm Developer roller sleeve
75.3mm Lower fuser roller
94.2mm OPC drum
This article originally appeared in the November 2009 issue of Recharger.