JRC JMR-92 Series Field Service Manual page 758

Rollback of the Software
5.5
Do not turn off the power during Rollback.
Otherwise, a function may fail, and an accident may occur.
Do not do the rollback operation of data while sailing.
The radar application should be ended to begin the data backup. It becomes
impossible to observe using radar and this may lead to accidents.
Whenever you try to perform rollback, always make sure that the backup power
is fed to the PSU of the Display Unit. Unexpected shutdown during rollback may
cause a system malfunction.
By rollback operation, you can downgrade MFD software version to the previous version.
The software version you can downgrade is until the version you have updated just
before. You cannot downgrade the software version to the second or more versions from
the latest install version.
If the software of the Display Unit have never updated ever, you cannot downgrade it.
1.
Turn on the Display Unit power.
The splash screen will appear.
5-15 Section 5 Software Update