Hello Hector,
Is the format of the revision in your sandbox ANSI or UTF-8?
From the --guiCharacvterEncoding=value option for si diff in the Source Integrity 10.6 CLI Reference, by default, the cahracter set in the perferences matches the default character set provided by the client's operating system, and the encoding preferences for each view and command can be set in the client. For instance, if you go to the client menu to Client --> Preferences, and then in the Preferences Configuration window's left pane drill down to Configuration Management --> Commands --> Merge, in the right pane you will see a drop-down for Character encoding.
Let me know if that helps.
Regards,
Kael