Hello, I am new here and relatively new to the emergency equipment world. I am looking to get ahold of a Federal Signal PA500M or some other PA500 device that is compatible with a PA500L controller. I have very little information on the 500L itself and I cant seem to get it to power on because I cant figure out the ground wire as it is internally soldered to the device. Any information on any of these units or if there is a modern alternative to bring life back to the PA500L is appreciated. I have looked in quite a few places and have found very little and haven't seen much for sale. Thank you!