How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Nathan Your Own Question
Nathan, Engineer
Category: Printers
Satisfied Customers: 24929
Experience:  Computer networking/repair. 12+ years experience.
Type Your Printers Question Here...
Nathan is online now
A new question is answered every 9 seconds

My brother mfc-9840cdw shows"unable print 21"

Customer Question

my brother mfc-9840cdw shows"unable print 21"
Submitted: 2 years ago.
Category: Printers
Expert:  Nathan replied 2 years ago.
Hello, I’m Nathan, and I’ll be assisting you today. My livelihood depends on your positive feedback, so your satisfaction is my highest priority. Sorry to hear you’re having trouble.
Expert:  Nathan replied 2 years ago.
Unfortunately, this error is the result of a hardware fault, specifically it is a beam/detect error, meaning a fault in the laser/imaging unit assembly. While there are a few steps that we can try to dismantle and clean the printer, this almost always comes down to a hardware fault that will require extensive repairs to correct.The cost of parts and labor to repair the imaging unit will be as much or more than a whole new printer, and if you're at the point that this item has failed then the age/usage is sufficient that other wear items such as the fixing unit, belts, etc are at their end of life also, compounding the costs and making the repair investment even less practical. If you have the time and inclination to get inside the printer, I'm happy to guide you through some steps here for cleaning/resetting, but in all likelihood you'll end up needing to make the repair/replace decision anyway. If you'd prefer help finding a local repair shop, or replacement recommendations, just let me know. Best regards, ***** ***** for the news,Nathan
Customer: replied 2 years ago.
I did some poking around on-line and saw that this fault often requires replacement of the laser scanner unit. Is that what you're calling the imaging unit? I'm pretty mechanically inclined - is this a replacement I can make myself?
Expert:  Nathan replied 2 years ago.
Yes, that is exactly what I'm referring to.This is not a quick or simple job, even for an experienced printer tech. That isn't to say it isn't possible, but it involves fully dismantling the printer handling the very sensitive laser assembly and optics which are easily damaged. Much of the casing is press fit plastic that breaks when assembling/disassembling, so chances of getting it properly installed without harming something else is high.The part alone is about $450. Given the other wear items that would need replacement in the near future, I'd lean toward replacement when you can get a brand new comparable model printer for about the same price as the part: you prefer to replace, you can get the part here:'d suggest purchasing a service manual to guide you through with specific diagrams. Best regards,Nathan