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Spent 4 hours chasing a phantom door fault on an old Otis last week | Elevator Mechanics - HW Forums

Spent 4 hours chasing a phantom door fault on an old Otis last week

Elevator in a 12-story office building downtown kept throwing a door zone fault at random times, no pattern at all. I swapped the door locks, checked the wiring, even replaced the door operator belt (which was fine). Turned out to be a loose ground wire on the controller cabinet door, of all things. Has anyone else had a gremlin that took way too long to find just because of a bad ground?

2 comments

2 Comments

lewis.diana5mo ago

OH MAN, you are SO right about that. I used to be the guy who would ALWAYS skip the grounds first and go straight for the expensive parts. I thought it was too BASIC and never the REAL problem. But then I had a ThyssenKrupp in a mall that was driving me NUTS for three days. Chased a phantom door lock fault that only showed up when someone slammed a door on the 2nd floor. Swapped the whole door operator, replaced the motor controller, the works. Finally, my old timer coworker walks over, jiggles the ground wire on the control box, and the fault CLEARS. I felt like a COMPLETE idiot. Now I always check grounds first, no exceptions. It's the cheapest fix and the one I always ignored.

thead445mo ago

Oh man, don't you hate those! I had a similar thing on a twenty year old Mowat in a medical building. Chased a sporadic fault for the better part of a week. Swapped relays, cleaned every connection, even replaced a perfectly good limit switch. The answer was a loose ground screw on the main power supply. It would just barely make contact most of the time, but a big enough vibration would make it lose connection and the whole controller would glitch. Now I always start with the grounds before I do anything else. It's amazing how many little mysteries a bad ground can cause.