Troubleshooting; No Power - Bunn Ultra-1 Service & Repair Manual

A troubleshooting guide is provided to suggest probable causes and remedies for the most likely problems
encountered. If the problem remains after exhausting the troubleshooting steps, contact the Bunn-O-Matic
Technical Service Department.
• Inspection, testing, and repair of electrical equipment should be performed only by qualified service personnel.
• All electronic components have 120 volt ac and/or low voltage dc potential on their terminals. Shorting of
terminals or the application of external voltages may result in board failure.
• Intermittent operation of electronic circuit boards is unlikely. Board failure will normally be permanent. If an
intermittent condition is encountered, the cause will likely be a switch contact or a loose connection at a
terminal or crimp.
• Keep away from combustibles.
• Exercise extreme caution when servicing electrical equipment.
WARNING
• Unplug the dispenser when servicing, except when electrical tests are specified.
• Follow recommended service procedures
• Replace all protective shields or safety notices
No
Call licensed
electrician for repair
Yes
Replace Control
Board

TROUBLESHOOTING

No Power

Correct voltage
at outlet?
Yes
Does Membrane
Switch test ok?
Replace Membrane
Switch
Yes
12vac to Control Board
at J5-8 & J5-20?
No
No
Replace
Transformer
14
No
12vac from secondary
of transformer?
Yes
Check main
wiring harness