Have you ever been wondering, why the Alix 2D13 never made any sound? Then yours was probably also shipped without the small piezo buzzer populated. It seems like all the 2D13s were practically fully equiped with the exception of this small device.
The photo shows the area where the component BU1 should be mounted but never was. All the rest (driver etc.) is present. So solving this problem implies soldering just a suitable piezo buzzer here. After contact with pc-engines as my local distributer I got the info that a buzzer can be ordered from their web shop by ordering the item “special” [1] and leaving the note “1* buzzer”in the comment field. Be sure to select the PC Engines direct shop instead of a local distributor (See [2]). The total amount for the order of 1 buzzer is 0.50€ plus 3.40€ shipping and handling.
After delivery just solder the HY-05 buzzer to the PCB where item BU1 is located and you are done. At least all current Linux systems should now be abled to attract your attention through a simple beep. Be sure to observe the correct polarity and align the cathode to where the + sign on the PCB is located.
Please be aware that any modification to your hardware may lead to a loss of warranty. Use this information at your own risk. I am not responsible for any damage to your equipment.
References
[1] http://www.pcengines.ch/special.htm
[2] http://www.pcengines.ch/order1.php?c=2