I had a really annoying problem with a lock connected by a dry contact to fingerprint scanner. The person who installed it 5 years ago did a horrible job and after all that time the wire shorted together to I had to replace the botched wiring job after I replaced all the wiring I find I’m getting some interference from somewhere that’s causing the lock to open close randomly. After 3 hours of bashing my head agaisnt the wall I figured out the the 12v transformer for the fingerprint scanner wasn’t working right…it was causing the fingerprint scanner to send pulses every couple of seconds to the lock to open.
