It seems the issue is your coin acceptor is constantly sending signals to your USB encoder, and that's triggering the button input. Some things to troubleshoot, to see if the coin acceptor is correctly interfaced and talking with your system:
Wiring
Confirm the wiring between the coin acceptor and the USB encoder is correct. The coin acceptor should send a signal, only when a coin is inserted. Make sure the 'COIN' or equivalent signal wire from the coin acceptor is connected to the correct input on the USB encoder.
Coin Acceptor Configuration
Many coin acceptors have DIP switches, or programming menus, that allow you to configure how they operate. Check the manual for your specific coin acceptor model and see if there's a setting that controls the duration or type of the output signal. You may want to try sending a momentary signal, instead a continuous signal.
Pull-Up or Pull-Down Resistor
Depending on the design of your coin acceptor and USB encoder, you might need to use a pull-up or pull-down resistor on the signal line to ensure it only sends a signal when a coin is detected. This can help prevent 'floating' signals which can be interpreted as continual button presses.
Microcontroller
An advanced solution is to use a microcontroller, like an Arduino, to read the signal from the coin acceptor and then send a clean and single signal directly to the USB encoder. This will give you complete control over the signal, but does requires additional hardware and programming.
Coin Acceptor
If all else fails, you might have a faulty or incompatible coin acceptor. Lookup you specific USB encoder and then try to find a model that is known to work so there are no compatibility issues.
Hope that helps. Let us know how it goes!
