minidisc audio recorders
Many minidisc recorders have a "hold" mode that temporarily suspends operation of most of the buttons on the recorder. You might use this when you've selected a number of settings in preparation for a recording and you don't want to accidentally press a button and change any of the settings you've selected.
But sometimes you'll accidentally go into hold mode (by accidentally pushing the hold button), and then will not be able to change any of the settings or get the recorder to function as you want.
On the Sharp Net MD and MD-MT90 minidisc recorders, you'll know you're in hold mode if the recorder screen displays the word "hold" or "hold on" when you push any of the buttons.
To get out of hold mode, you need to press down on the off/hold button for several seconds until the words "hold off" are displayed on the recorder screen.
Similarly, if you do want to go into hold mode, press down on the tiny off/hold button for several seconds until the word "hold" or "hold on" is displayed on the recorder screen.
On the Sharp Net MD minidisc recorder, the off/hold button is at the bottom of the main large button.
On the Sharp MD-MT90 minidisc recorder, the off/hold button is a separate button on the top of the recorder.