TM21 troubleshooting checklist: Connecting the power: On the supplied power supply, the black wire with the white line is the + voltage. This should be attached to the terminal labelled VDC (or POWER on the Version 1 TM21s). The solid black wire is the Power GROUND and is connected to the GND terminal. Connecting a button: Connect COMMON on the pushbutton the GROUND (GND) on the TM21. The NO (normally open) contact on the button should then be connected to the TRIGGER (TRG) terminal on the TM21. Checklist: __ Power LED should be ON when the power supply is plugged in. __ Entering DNO into the MODE.TXT file should automatically play file 001.mp3. __ MP3 files should be MPEG 1 LEVEL 3 **not** MPEG2 LEVEL 3. __ Using a SD card formatted to FAT16 or SDHC card formatted to FAT32. __ Audio files start with 001,002,003 etc __ Volume is turned up (clockwise) even if you are using the line output. __ Nothing else (i.e. mac trash files or directories) other that the audio files and the MODE.TXT on SD card. __ A-Data SDHC cards have been a problem (3 customers have reported cards corrupting) __ Check the voltage on the TRIGGER terminal - should be at 2.9 VDC. Sample test files: Sample test files are available at www.technovision.com/ftp/TEST_MEDIA/TECMP3