depends..
if you have a test vend button, wire up to that and use a push button switch to activate..
on my old rowe changer, the computer part was shot... my rowe also is old enough that it used to take 50 cent pieces...
so i wired the little door/solenoid that "spits the coins" so its open at all times.. I then wired 110vac to the hopper motor and the circuit is completed via a pushbutton switch mounted inside the frt door. THeres a coin retuen lever on mine bieng it used to take 50 cent pieces so i made the coin return lever acuate the switch. So now when i hold down the coin return lever, the hopper motor runs and she spits out tokens...
I would strongly reccomend the test vend button to external button method if you changer is in proper working order.
My way was done because my machine is just totally effed otherwise lol