Turning off sleep mode on mfc-9840 printer
This may help some (22Jun2022): MFC-9840CDW using wi-fi option to connect, currently running on Windows 11 and for a long while, years even Windows 10, I too was constantly having a problem of this machine going into sleep mode and not coming out when wanting to print, the driver/firmware is the latest from the brother's support site for this model. The actual printer machine: no status light, says "Sleep" and the "menu key button" does not respond (need this key to respond). The PC, the brother printer icon does show in the control panel but do not have the "set as default printer" option. I assume in sleep or deep mode the PC does not see the actual printing device. In my case, Brother PC-Fax v.2.1 was selected and I could still scan a document to my PC. Fix action (need to turn off sleep mode on the printer itself): turn off printer (maybe wait 5 min, probably don't have to wait). turn printer back on, it cycles itself the status light on the printer should be green, at this point the printer should work as normal. But you should immediately turn off "sleep mode" because once it goes into sleep mode it no longer responds. Press the "Menu" key, enter "general setup" press "OK" button, arrow down to "ecology" (6) press "OK" button, select "Sleep Time" enter 000, press "OK" should respond with "accepted". After I did this, I currently have no status light and it still says "sleep" just like before. I just did this and it's been a couple of hours and I can print a test page whereas before I could not. And the icon in the control panel is as it should be, a check mark showing its the default printer. Hopefully, this is a permanent fix at least until I replace this printer.
6/22/2022 7:23:02 PM •
on Jun 22, 2022