Xerox 7425 Style Fuser Modules – Part 2

Hello again! Welcome back for Part 2 on the WC-7425 style Fuser Modules. Last month we took one of these things about half way apart and now we’ll finish the procedure up. First let’s do a quick refresher, and then get going towards removing the Fuser heat Roller.

In Part 1 of this procedure (steps 1-4), we removed the two “outer” covers and the one “inner” cover. Then we loosened up and disconnected the front heat lamp wires. Next we took some notes about the positions of the Pressure Tower screws, and then backed the screws out so we could hinge the Pressure Sleeve Assembly off of the rest of the fuser. Below is a photo of where we left off.

Now let’s get right back into it with the next step.
5. Remove the Heat Roll Stripper Plate (black plastic, 3 screws), but first mark either end to help guide you later during reassembly.

6. Next you’ll want to clear up a little bit of clearance for the Heat Lamp to shift towards the rear end (you will need every millimeter of clearance you can get). To loosen up the metal plate which holds the rear ceramic plate, remove one screw (screw #1 on Photo #12).

7. Loosen up the Far Rear End metal frame (the one which holds the Main Fuser Connector) by removing 3 screws. One of the screws (#1 on Photo #13) is near the Exit Idler Assembly and the two other screws are at the very far end (#2 & 3 on Photo #13). With this plate loose you can get to the CRUM board (fuser board). Disconnect it and fish it out of its alcove (see Photo #13). You need to replace the 20 Milliamp fuse (soldering is required).

8. Let’s get the Exit Idler Gear Bracket out of your way next, because it will get in the way of removing the Heat Roller. Remove two screws (#2 & 3 on Photo #12).

9. Now very gently turn the fuser over (the heat roll is loose at the front end, so it will drop down a bit and you don’t want to damage the glass lamp by any sudden moves). Remove one screw from the wiring harness channel piece, which is a black plastic piece which holds several wires (see Photo #14) and then pry from above with a small flat-head screwdriver (see Photo #15).

10. Next comes the Thermistor / Thermostat Assembly. Remove the 5 screws along the length of it (see Photo #16), then shift the Far Rear Metal End Plate towards the rear end, lift the front end of the Thermistor / Thermostat Assembly, and “hinge” it away from the frame (see Photo #17). Be especially careful not to damage the Thermistor head which is tucked under the metal frame nearest the rear end.

11. Now free up the front wires of the Fuser Heat Lamp by first shifting the lamp and all of the metal plates near the rear end of the lamp towards the rear end until the wiring at the front end has just enough clearance to sneak it out from under the lamp’s front metal holder plate (see Photo #19).

12. With the wires freed up, you can now lift the front end of the Fuser Heat Roll up and slide it out over the twin Heat Lamp Assembly (see Photo #20).

13. Now just as you thought you have this thing licked, you still have one more bit of trepidation. You need to come up with some gentle yet powerful way to remove the Heat Roll Bearings. These are pressed in place. I found that a large pair of channel locks and a hammer did the trick (see Photo #21). Hammering the bearings onto the new heat roll offered a similar challenge. Make sure to put the bearings on the new heat roll so that the flanges are away from the center of the roller (you don’t want to have to remove the bearings once they’re on, that’s for sure). You can use one bearing to help push the other one onto the front end. Then slide the second bearing onto the rear end where the cutout for the Drive Gear is. It needs to slide on just beyond where the cutout ends. I found that I needed the channel locks again to get it on the last couple of millimeters.

Now you can go ahead and reassemble everything. Take your time–you’ll find that there are little indexing nubs on several of the metal plates which helps get them positioned properly during reassembly. The black plastic Stripper Plate is one place you want to pay close attention to what you’re doing. Use the marks you made to find the plate’s original position as closely as you can. There is plenty of play there; you want the plate as close to the heat roll’s surface as possible on either end, without allowing it to make contact.

That’s a wrap! Hopefully with this set of articles in hand, you’ll find this fuser a little less intimidating. I’m confident that after having rebuilt a few of these, they will become familiar and a whole lot easier to work on.