Sony 4-127-580-13(1) Operating Instructions Manual page 116

Symptom
A file name is not
displayed.
Playback sound becomes
loud unexpectedly.
Please note that recorded messages may be erased during service or repair work.
11
GB
Remedy
If an LPEC, MP3, or WMA file has no title, a file name is

displayed instead. If you want to display a title, enter it using
computer.
The title/artist name of an LPCM file cannot be displayed as

title/artist name is not supported. In this case a file name is
displayed.
"V-UP" is set to "MAXIMUM" or "MEDIUM. " Set it to "OFF"

(page 85).