Hi there,
your hi-hat pedal input on the megadrum should be a jack with 3 connections.. so called tip, ring, and sleeve. Typically the sleeve would be 0v (ground) tip and ring will be 5v and signal or vice-versa depending on how you connected it (measure it with a multi-meter) or just check your connections.. in the syntex pcb there is a jumper (or switch) to cross these two over or not.
the hall sensor is just connected directly.. one pin to each. you should check the data sheet of the sensor to know which is which.
Here is data sheet for the sensor I used
http://www.jaycar.com.au/images_uploaded/UGN3503.PDFhere is the one for yours which seem to be the same sensitivity and brand as mine (1.3mv/G) but different model / packaging
http://pdf1.alldatasheet.com/datasheet- ... A1302.htmlnote that the magnet should oriented with North side towards the label. this will give approx 2.5v out when magnet is far from the sensor (hh open) and about 1.3v out when the magnet is close (ie hh closed). the distance away from the sensor that you can move before reaching full open I think is a function of the magnet size (not peak strength). If you are placing in the pedal then maximum distance does not matter so much... if directly in the top of the hh then its more important. (with a small magnet the range may be very short)
the actual mega drum settings for high and low can be adjusted to make these equal to full open / full closed (I can't remember the exact values I used but its easy to do by trial)
hope this is helpful
Dean