MFC-7840W FAQs & Troubleshooting MFC-7840W Not your product? Sort by: Updated Date Popularity 2 Results 1. 16/11/2015 I heard a beep sound from the UPS (Uninterruptible Power Supply) when I turned on my Brother machine. 2. 08/05/2013 The keys on the control panel do not respond. More FAQs Others FAQs & Troubleshooting