On most chesscomputers with a HD6301, the user needs to turn off the power manually, otherwise battery save won't work right. This is either with a STOP button (eg. Mephisto Europa, Saitek Leonardo), or with a power off switch which is mapped to the F1 key in MAME.

By the way, a similarity between Sphinx 40 and Triomphe/Y301XL, which may be coincidental, or could be due to being programmed by the same person (Mark Taylor?)... or someone else programmed the user interface.
The similarity is that they all play an (annoying) jingle when the CPU makes a reply move.