Hi, I have the ultimarc IPAC 2 since 2016. It worked great...and it still works great..if I dont use "COIN 1". If "COIN 1" is set to a key, it spams the selected key on the keyboard, as if it was stuck on the keyboard. I checked cables, the button and even upgraded to Firmware 1.50a. No matter which PC and/or Laptop I attach the IPAC 2...when "COIN 1" is set, it gets a continous signal. Even if the cables arent attached to the arcade button. I can play fine WITHOUT having a key set for COIN 1...except I cant use COIN 1 :'( Any idea ?
Start by disconnecting the wire from the terminal on the board just in case you have a wiring harness short. If it still does it, examine the board for shorts or bent pins on the chip. If you can't find anything, it's most likely that that specific pin on the chip is blown up - in which case all you can really do is replace the board or see if they will fix it.
If it's literally just Coin 1, it sounds like it shorted out. I'd, as the above mentioned, remove all wires to / from the button and start fresh. If that doesn't solve things and you can get ahold of the schematic, I'd beep everything out to see if I could find where the short existed
