Sometimes the unit freezes on the "Roland Juno-Di" splash screen. While this is often a firmware issue, it can be a hardware fault in the flash memory.
The first step in any repair or servicing work is to distinguish between the available manuals and understand what each one contains. roland juno di service manual work
Roland generally reserves service manuals for authorized technicians, but many PDF copies circulate in vintage synth communities and archival sites. When searching for "Roland Juno-Di service manual work," ensure you are looking for the official technical version (usually 30+ pages) rather than the 2-page "Reference Manual." Sometimes the unit freezes on the "Roland Juno-Di"
-inch audio outputs, headphone jack, microphone input, MIDI ports, and the DC power input jack. Be mindful of screw sizes, as they can differ
This section provides detailed schematic diagrams for the Roland Juno DI:
Flip the synth over and remove the screws fastening the bottom panel. Be mindful of screw sizes, as they can differ.
This is perhaps the most powerful section for anyone performing a repair. The service manual will explain how to put the Juno-Di into a special "Test Mode". This mode runs automated checks on the keyboard, the LEDs, the LCD screen, and all the buttons. You can use this to quickly determine if a non-responsive button is a physical switch failure or an internal logic problem.