Re: Miraculous button makes things work again.

Jeff,

Very interesting in general, and I just bought a Brother MFC-L8905CDW.
Have you encountered any of those yet?

What the above replaced was an ancient Brother MFC-9840CDW, and I did
have and repair many problems, and got 15 years out of it.

Thanks,

Joe


On Fri, 31 Jan 2025 22:02:41 -0800, Jeff Liebermann <jeffl@cruzio.com>
wrote:

On Fri, 31 Jan 2025 16:24:16 -0800, john larkin <jl@glen--canyon.com>
wrote:
>

What are the Brother design defects?

>
Brother MFC-L2740DW printer:
<https://www.google.com/search?q=brother%20mfc%20L2740dw&udm=2>
The problem appears on many similar Brother laser printers.
>
If the owner pulls out the paper tray while it's printing, the printer
does not stop printing.  Instead, it cracks the tiny feed gear.  I
have some photos I took of the damage and subsequent repair, but I
can't find them right now.
>
In the front center of the paper tray, there is a translucent roller
that is part of the paper feed mechanism.  Static electricity causes
this roller to be packed with paper dust and eventually stop turning,
causing a paper jam or other paper feed failure.  The paper dust hides
UNDER the translucent roller and is easily cleaned out if you can
figure out how it's done.  I can take a few photos showing how if you
want them.
>
Near the translucent roller in the paper tray is a friction pap.  The
pad and the feed roller above its position in the paper tray tend to
develop a smooth polish.  The loss of friction causes feed failures.
Brother's idea of repair parts are toner carts and drums:
<https://www.brother-usa.com/supplies-and-accessories-search-result#q=MFC-L2740dw>
A trick the works on some printers is to remove the rubber roller or
pad, flip it over, and reinstall it.  Fortunately, 3rd party vendors
carry suck parts.
>
The paper stop near the back of the paper tray is fragile.  Push too
hard inserting a stack of paper and it will break.  This should work
as a replacement:
<https://www.parts-distribution.com/collections/brother/products/new-oem-brother-250-page-rear-paper-guide-for-mfcl2700dw-mfc-l2700dw>
>
The main PCB in the printer uses a super capacitor instead of the
usual lithium coin cell to provide power to the circuitry that stores
the printer settings.  When it fails, printer won't turn on. Replacing
the super capacitor involves disassembly and soldering. YouTube video
on how to replace the super cap:
<https://www.youtube.com/watch?v=OgkHv1c01tQ>
<https://www.ifixit.com/Guide/Brother+MFC-J4420DW+Capacitor+Replacement/74271>
The caps are 5.5VDC 0.22Farads. 
<https://www.google.com/search?q=KR-5r5V224-R>
>
That should be enough for now...