Machine Error 71 – Brother Fax 4100, 4100e, 4750, 4750e
The machine error 71  message in the Brother  Fax 4100, 4100e, 4750, 4750e  machines is related to the laser/ scanner unit motor. With these machines getting older this problem is becoming more of an issue.  When the machine starts its warmup cycle to print the laser / scanner motor comes up to speed and attempt to sync with the print engine motors rotation so the image is correctly positioned on the drum.  The  laser / scanner motors  rotation can reach anywhere between 20,000 to 40,000 RPM’s depending on the print speed of the machine. The quicker the print speed the faster the motor rotated.  Once the laser / scanner motor reaches it correct operating speed the paper feeds through and the laser writes  to the drum unit producing an image.  If the Brother  Fax 4100, 4100e, 4750, 4750e laser unit doesn’t reach that specific speed in a certain amount of time then they display a 71 machine error on the display.
Troubleshooting the machine error 71  on Brother  Machine Error 71 – Fax 4100, 4100e, 4750, 4750e machines.
Troubleshooting thmachine  error 71 on Brother  Fax 4100, 4100e, 4750, 4750e   machines can be pretty simple because  the machine is usually either giving you an error, running extremely noisy, or the customer complains that it comes and goes. I always ask my customers if the machine has been running more noisy than usual leading up to the error. Dirt, dust or dryness between the polygon mirror post and the motor bushings is what causes  the noise and the 71 machine error.   As the machine gets up to speed the friction between the motor bushing and post generate a noise and if bad enough result in a 71 machine error.  I’ve also  have had customers relate it to the sound generated as an airplane taking off. Because  the noise starts off soft and gradually grows louder and louder until it fail or if your lucky finally prints off your  document.  Most times the machine goes to a ready state when turned on but once you send a print or copy job to it fails. Hopefully, if your servicing the machine you will be able to hear the noise as the machine starts up to print so you can truly  verify the problem. Even if you don’t hear the problem, if your called out for this error and the machine is working fine when your on site, it’s best just to quote the replacement of the laser / scanner unit to save you problems in the long run.
Repair the Machine Error 71 on Brother  Fax 4100, 4100e, 4750, 4750e machines.
You can fix the 71 machine error in two ways. First,  is to replace the laser / scanner unit. I strongly recommend handling your repair this way if your a technician doing this for one of your customers. The removal procedure for the laser / scanner in Brother machines is a lot more difficult and time consuming than HP’s. Experienced technicians shouldn’t have a hard time doing this repair.  For some one who has never attempted something ike this before  it could be overwhelming. For anybody planning on doing this, even technicians,  that hasn’t done one before I would recommend finding a service manual first before disassembly. Several parts are tricky to remove and if not done properly can be damaged.  Second option is to remove the laser / scanner unit, take out the polygon motor (don’t touch mirrors or lenses), clean off the shaft the goes into the motor bushings and using a light oil lubricate the post and bushings. I always just replace the laser / scanner unit for the 71 machine error because  the unit is  not  very expensive, it’s  time consuming to get it out of the machine, and the cleaning and lubricate repair  tends to not last even if you can get it to work.  If it was my personal machine I probably would take it apart and lubricate it to save  money but from a professional point I would not do that to my customers. My job is to do the best work that I can and hopefully not see my customers for repeat problems on issues I could have corrected the first time by replacing. So  I replace the laser unit for a machine error 71  on  Brother  Fax 4100, 4100e, 4750, 4750e machines to protect my reputation and fix it right the first time.
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So, I took our Brother apart and found the polygon motor. Yeah, it was a little stiff to turn. So how do I lube the shaft? Does the shaft pull out from the bushing? Or do I need to get that spring washer off the top of the ‘gon to get to the shaft? Got a photo?