Technical Tip: Rebuilding and Repairing Xerox 7525 Family Fuser Modules Part 1 of 2

Repairing and Rebuilding the Fusers for the WorkCentre^® 7525, 7530, 7535, 7830, 7835; WC-7545, 7556, 7845, 7855; and Phaser^® 7800

The WC-75xx and WC-78xx family fuser modules are pretty serious pieces of equipment. With the advent of aftermarket parts becoming available at long last, it’s time to take these apart and figure out the best way to go about replacing the fuser heat belt, pressure roller, and the fuser reset fuse. You will find this one is relatively time consuming to rebuild, but with the new fusers retailing for over $700, they are well worth your time. It is a long instructional so we’ll cover it in two articles.

These things are well built with a stated yield of 360K pages. They are not typical of other Xerox fusers we’ve covered. For one thing, they use a flexible heat belt rather than a rigid heat roll like most fusers. Then for the heating they don’t use traditional fuser lamps. Instead, these use a newer technology known as induction heating which reduces the amount of energy required to keep it hot. The heat on the heat belt’s surface is produced by a piece that is adjacent to the heat belt, not inside it as one might expect. Inside the heat belt you’ll instead find a thermal control assembly, which has the thermistors and thermostats mounted to it. The pressure is taken care of by a more traditional looking pressure roller rather than a pressure sleeve as we’ve seen in recent models. It is said that the pressure roll often fails before the heat belt is worn out. The pressure roll tends to swell and seize up late in the fuser’s lifecycle. So in this case it’s important to replace both pieces when rebuilding one of these fusers.

There are two very similar versions which both come apart the same way. There is a low-speed version and a high-speed version. Also there are printer models that have their own part numbers. Below are the part numbers and which models each one is designed for:

For WC-7525/7530/7535 & WC-7830/7835:

604K62200 – 110 Volt version (or 604K94290 for an OEM Rebuilt fuser)

604K62220 – 220 Volt version

For WC-7545/7556, WC-7845/7855 & WC-7970

604K62210 – 110 Volt version (or 604K94280 for an OEM Rebuilt fuser)

604K62230 – 220 Volt version

For Phaser^® 7800:

115R00073 – 110 Volt version (Alternate #: 676K12630)

115R00074 – 220 Volt version (Alternate #: 676K12640)

REBUILD PROCEDURE (Part 1 of 2): 

Tools Needed:

• Safety Torx T-15 Driver (Safety Torx drivers are the kind with the hole in the center of the driver bit. Not everyone has one of these handy. There are five of these types of screws holding the outer and inner covers in place. These are high-domed screws, so if you’re stuck and you don’t have a Safety T-15 driver, you could use needle-nose pliers to work them off one turn at a time (time consuming, but doable).
• Phillips Head #2 Screwdriver (also a 5.5mm hex driver is helpful)
• Small Flat-Head Screw Driver

Orientation:

Let’s start by getting oriented (refer to Photo #1). The rear end is the end with most of the gears and the main fuser connector, which interfaces with the machine. You’ll also find the CRUM reset fuse board tucked into the rear end.   The outer face is the face that is visible when you open the machine’s left door to go remove the fuser. It has a bunch of warning labels on it and the two thumbscrews for removing the fuser are found on the bottom edge of this outer face. The top of the fuser is where the yellow fuser exit gate can be found. Now let’s strip this baby down.

1. Remove the Outer Cover (3 Safety-Torx T15 screws from the outer face). The yellow exit gate pivots on the top of this outer cover. If you wish to remove the exit gate, it is held captive by a small black plastic pin, which holds the front-most pivot point. If you slide the plastic pin out of place with your thumb, the gate can come off (see Photo #2).
2. Remove the Inner Cover (2 Safety-Torx T15 screws from the inner face). See Photos #3 & #4.
3. Release the Outer Frame. This is a long metal piece with an attached black plastic channel on which the fuser exit actuator hangs (2 Phillips head screws from the outer face). Disconnect the electrical connector at the rear end of the long blue wiring harness (see Photo #5). Then pivot the channel and metal piece away from the rear end (it is still connected at this point at the front end of the fuser).
4. Remove the Front Wiring Guide (black plastic). Refer to Photo #6. First, disconnect the fuser exit sensor’s bracket (1 screw) and then disconnect the white plug from the fuser motion sensor which watches the fuser turning (this optical interrupt sensor watches the edge of a wheel with a series of flags on it). Shift the front wiring guide (black plastic) towards the outer face till it clears the metal frame (to the right in the photo). Next, fish the white plug near the middle of the black plastic piece out of its fastening hooks so that you can disconnect the white wire, which disappears into the front end of the fuser heat belt.
5. Remove the Pressure Roller Tie-Bar (2 Phillips head screws) and the Paper Input Guide (also held by 2 Phillips head screws). See Photo #7 for a close-up of which screws you’ll be removing near the rear end. There is a static dissipating resistor mounted under the paper input guide.
6. Remove the small black bracket which holds the Fuser CRUM Board from the rear end (1 screw). The fuser CRUM board on this fuser has a 20 milliamp fuse soldered in place and an indexing resistor. It is necessary to replace the fuse so that the fuser count will reset when you install the rebuilt fuser. The fuse must be soldered onto the CRUM board.
7. Release the large Main Fuser Connector. It is near the rear end (2 spring loaded shoulder screws).
8. Release the Rear Wire Guide (black plastic). This holds many of the wiring harnesses (1 screw near the center of it, see Photo #8). Then pivot the far rear portion towards the inner face and off. Be patient, you will need to remove some of the wiring from its channels to get this piece far enough out of your way. For reassembly, refer to Photo #8 to see where the wiring is supposed to go.
9. Remove the Pressure Cam Shaft’s Home Sensor Actuator (1 screw, see Photo #9). Next remove the Pressure Cam Shaft Assembly by removing the e-clip at the front end and a second e-clip just behind the metal frame piece at the rear end between the rear cam and the cam shaft home sensor actuator flag (see Photo # 9). You’ll need to slide the cam shaft to the rear, far enough for the front end of the shaft to clear the front metal frame and lift the front end up. Then it will slide toward the front until the shaft clears its drive gear. Watch out not to lose any small pieces. The front and rear bearings will fall right off, as will the cam shaft drive gear and a plastic bushing found in the frame near the drive gear. Notes for reassembling the pressure cam shaft assembly: the cams and the home sensor actuator flag line up with their rounded parts facing the same way. The 2 bearings have their flanges positioned outside of the metal frame on both ends. When reassembling, you will need to place the drive gear in its place and slide the “D-shaft” in to meet it.

To be continued…We’re getting there! This instructional is a bit too long to fit into one article, so we’ll finish up next month. Tune in next time when we’ll soldier on to remove some metal framework from the rear end, followed by the pressure roll assembly, and finally the fuser heat sleeve slides off of the thermal control assembly.