Rise!
Late to the party by 11 years, but I have some info for those that still have these change mate 50 machines! Now days even used change machines are too expensive and most large and bulky. The Change Mate 50 is great for home arcade use, cheap, and it's small profile is ideal. The 120v bypass momentary switch recommended above was a nice fix, but I wanted to feed it real bills for the nostalgia. If you are up for a little project here is how to do it!
The bill validators on these CM-50 units are a real pain and old only sometimes accepting $1 bills if you are lucky. I had 2 I tried to get to work, but even after a cleaning, recap, new magnetic heads, crisp bills, eeprom dump verifications, it would only accept maybe 1/50 times. I spent too much time trying to make it work, but there is another solution:
Upgrade to a Top TB74 12v Bill validator! It will work with the new $1,$5 even up to $20 bills, for this small change mate unit, I'll disable everything after $5. The TB74 has a small profile, and you can dremmel cut through the metal of the Change Mate CM50 lid and mount the TB74 into the top of the unit or you could do it on the side. We then can splice or piggyback solder into the CM50 wiring harness with
a small latching relay board running the show and it will utilize the existing 120v solenoid and drop the bills right down into the change mate 50. The old CM-50 bill validator can remain in place to fill the bottom void.
First ensure the CM50 power supply is working. The power supply is behind some metal shielding and is simply a wall ac/dv 12v adaptor plug, 380-400mAH with its 12v output lines going to the oem bill validator harness and the incoming 120v going to the ac/dc plug prongs. While this power supply will run the TB74 validator, you would want to match the power requirements and swap out the plug with a higher mAH. The Top manual
TB74 says 11-12v, 2A operating, but I ran it much lower without issue.
My TB74 came with 2 harnesses, a metal face bracket, sticker, a sticker surround (pic attached) around $65 shipped from Ali, prior to tariff increases.
The latching board will run on the existing CM50 12v lines. When the TB74 validates a bill it send a pulse to the latching board and will activate the 120V solenoid for a short pulse to dump the coins and then flip it off (
set the TB74 dip switches for 2 pulses/ $1 bill). Wire up the latching board (see pic) and jump into the existing CM50 harness for all the wire hookups.
Its a tight fit for the TB74 between the side lid and the quarter dispensers on the top but it will fit with some metal dremmel cutting and filing. Use the TB74 metal faceplate as a template. See pics for my cutting spot measurements. I ended up mounting the TB74 so its light is facing the user, since bills are accepted in any direction, it works nicely. This also allows the wiring harness plug of the TB74 to not be smashed up against the side of the Quarter dispenser.
Dip switch settings bank 1, 1-3: Off, Off, On (2 pulses 1/dollar). Customize the rest of the dips if you want bills accepted or rejected. A $5 will send a 5 time activation to the CM50 solenoid automatically to dispense the 20 quarters.
Dip switch setting bank 2, left on default settings.
Now you can run $1, even $5! When you first power it on, it will dispense once. If the solenoid is stuck on humming, push the latching board red switch button so the LED light switches over to the Normally Open "N.O." spot. It will remember this moving forward.
Be careful with the live voltage, build a little project box to house the latching relay so it wont short out or you hit the bottom of the board when its live. Wear PPE when using the dremmel to cut the metal lid, it will cut through with a metal cutting blade.
Video of it operating, fyi only 1 quarter hopper was filled in that vid. fill all 4 tubes to have them dispense 4 quarters.
Good luck!