Mxb401 L4-12

[gwaddle]

I've searched and couldn't find anything on this code in the forum, if it's already here...sorry. I have an mxb401 that will get an L4-12, usually after running quite a few copies. I watched the 2turc clutch and when the code hits it's because the clutch keeps running. I've replaced the clutch and the main board, but of course that didn't help. There is a bulletin on this that says to look for a warped resist sensor unit. That doesn't appear to be the case. None of the bulletins mention the clutch continually running. Other ideas?

[Silvertoast]

Re: Mxb401 L4-12

the bulleitin refers to the unit warping to were it can move front to back. grab a hold of the unit and see if u can slide it front to back. i have had several that was warped and would walk toward the front of the machine causing the gears on the back not to mesh together. causing the code. also there is issues with the primary trans. the levers that lift the rollers up and down in the trains will break or snap out of place causing l4 codes.

another note. there is a gear in the drive unit that will get a hairline crack in it and cause l4 codes. (cant for the life of me remember the which gear and part#)
had several when the machines first came out but havent had to repl one in awhile

[mojorolla]

Re: Mxb401 L4-12

If the resist unit is to blame, an F2-45 will usually also show in the error log, but not always. Under the fuser are two slide shafts , the front one having a spring and being attached to the front of the resist unit. Being plastic and directly under the fuser, they can bind. You can remove and clean them, but be careful. The two little plastic tabs are molded into the frame and brittle from fuser heat.

[gwaddle]

Re: Mxb401 L4-12

Thanks for the info. I'll check all that out.

[JustManuals]

Re: Mxb401 L4-12

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[bdcrandall13]

Re: Mxb401 L4-12

The resist sensor unit plugs directly into a sensor that sits directly behind the primary trasfer unit. I cannot recall what the sensor is called off the top of my head but it can go bad as well. The bad part about this is that the parts guide lists the wrong part number for that sensor. If this sensor is failing the primary transfer belt cam will just turn and turn and turn and not stop until it codes. We dealt with this issue for weeks before finding out that SHARP had the wrong sensor listed and after we got it switched out with the right sensor it corrected the problem instantly. This has worked several times since then as well. Here is the parts number for the sensor. VHPGP1S73P+-18
A quick way to check this is to take the exact same sensor out of the bypass tray, (in the parts guide it is in section 8 number 17,) and replace the one behind the primary belt with it. That is a quick way to tell if the sensor is the problem without having to order anything.

Good luck.

[gwaddle]

Re: Mxb401 L4-12

Thanks for the input folks. I replaced the resist sensor unit this morning and it seems to have solved the issue. Thanks again.

[Ipcust]

Re: Mxb401 L4-12

I had my first of these today. I replaced the resist sensor unit and the problem seems to have gone away. Another thing to look at when replacing this unit, if you've got a machine that's been around awhile is pieces of eaten fuser drive gear. I am wondering if the remnants of one of these gears is what is binding the two slide shafts. It would make sense to me.

[Akitu]

Re: Mxb401 L4-12

Another point of reference is a previous firmware update to give a little more fault tolerance before throwing up the L4 code.