Try this site: http://www.combo-organ.com/
That site has tons of information about "combo" organs (which it the type of organ you have). These organs were portable and meant to be played in bands (combos) - there were many makes/models of them - most from the 60s-70s. Usually they have to plug intoa separate amplifier. The Music Mate brand/model does not "ring a bell" with me but maybe the people over at the website would know. Hope this helps.