Warning: this may affect your warranty if you change anything on the machine. I do not claim any responsibility for any damages done. 

Entering Test Mode on the Sharp MD-MT15

1. While the unit is powered off, hold down ENTER/SYNC+DISPLAY and press PLAY[>].
   

2. Hello appears for a split-second.
   

3. A version number appears on the screen, (mine is 318AfX)
   

4. All LCD components light up.
   

5. TEST appears. (pressing STOP at this point turns off the unit.)
   

To select a sub-mode, press BASS. AUTO1 appears. (pressing STOP at this point returns you to the test screen.) Use SKIP BACK <<and SKIP FORWARD>> to page through the sub mode choices:

AUTO1

AUTO2

T PLAY

T REC

MANU1
MANU2

RSLT1

RSLT2

DinMon

E DATA

MORMAL

EEPROM

INNER

Press PLAY [>] at one of these to enter that sub mode. The sub modes seem to be the same as those given for the MD-MS200, but aren't in the same order, and several are split up into 2, and may use different controls. In most of the sub modes, pressing STOP returns you to the test screen.

Entering test mode seems to reset the settings saved for A-PLAY, Psave, and BEEP.

Personally I haven't explored the submenus a lot, just entered several of them, and haven't touched anything other than STOP to return to the test screen. The one I've tried to explore was Normal mode, which let's you run your player like normal mode, but there's some additional info on the display (that is, it should do that). When I enter it, all it says is: 'ErADJ.'and that's all, whatever button I push, it doesn't matter, only the STOP button works, which gets me back to the test screen.