EM21D User’s Manual
Page 4 of 4
Additional Functions
Q Mode
The Q mode is enabled by adding the letter Q as the fourth letter in the
configuration file. In the Q mode, the left channel audio output is in-
verted. For stereo files this creates a virtual surround. For mono files this
quadruples the power output - in this case the speaker must be con-
nected between the LEFT and the RIGHT terminals.
Regular Mono
BTL Mono (4X Power Booster)
Since BTL mono provides four times the output power of regular mono
with the same supply voltage, it is often used to boost the output power
when the supply voltage is low. However, the speaker impedence should
be 8 Ohms or higher to avoid overloading the power amp.
Background Music
To loop play a file as background music when the system is not triggered,
name it BGM.mp3 and copy it to the memory card. The background
music is interrupted when the system gets triggered, and restarts from
the beginning after the trigger is handled.
The background music function is available for the TRG mode and the
Keypad mode only. It’s not available for the Timer mode.
Trouble Shooting Guide
Basic Test - TRG Operation
1. Connect power supply, push button and speakers.
2. Name an MP3 file 001.mp3 and copy it to an SD or SDHC card.
3. Make sure there is no configuration file on the card, so that the system
will operate in the default mode.
4. Insert the card into the unit while power is off.
5. Turn power on. If the power LED does not light up, check power supply
polarity and connections.
6. Press the push button and the file should play.
7. If no audio, make sure the volume knob is turned up.
Basic Test - Keypad Operation
1. Connect power supply, keypad and speakers. Make sure the keypad
is compatible.
2. Name an MP3 file 001.mp3 and copy it to an SD or SDHC card.
3. Create a plain text file called MODE.TXT and put KNB in it. Copy it to
the card.
4. Insert the card into the unit while power is off.
5. Turn power on. If the power LED does not light up, check power supply
polarity and connections.
6. Press 1# on the keypad and the file should play.
7. If no audio, make sure the volume knob is turned up.
Basic Test - Timer Operation
1. Connect power supply and speakers accordingly.
2. Name an MP3 file 001.mp3 and copy it to an SD or SDHC card.
3. Create a plain text file called MODE.TXT and put T01 in it. Copy it to
the card.
4. Insert the card into the unit while power is off.
5. Turn power on. If the power LED does not light up, check power supply
polarity and connections.
6. The file should start to play immediately. After playback is over, the file
will automatically play again after one minute of delay.
7. If no audio, make sure the volume knob is turned up.
Common Mistakes
* Files are not named/numbered properly.
* Wrong file types - only MP3 is supported.
* System configuration file is missing or incorrect.
* Unsupported cards such as SDXC are used.
* Trigger mechanism is either faulty or of the wrong polarity.
* Some wire connections are loose.
* Speaker volume is too low to be heard.
* Bad components such as push button, speaker and etc.
* Keypad is incompatible.
* Power supply is under powered. This may cause the audio to distort.
