First post.
I am working on the controls on a 1911 Monarch Model BB3 freight elevator. They blew a control fuse and when they replaced it the control box hummed so they turned it off. I replaced the fuse and when you power up the contactor for the UP direction tries to pull in but does not pull in enough to engage the motor. I disconnected the coil of the UP contactor and it powers up fine and manually engaging the contactor the motor runs fine. I assume that the very old coil is bad but do not understand why the elevator attempts to raise on power-up. All of the switches seem fine. The car is between floors; maybe it defaults up on power up?

Are these very old coils available, or would it be best to completely rewire the controls? The schematic for this unit is completely unreadable, any ideas where to find one?

[img]https://www.fndphoto.com/Photography/Work/n-x3JG7Q/Miscellaneous/i-fM6sVn4/A[/img]

[img]https://www.fndphoto.com/Photography/Work/n-x3JG7Q/Miscellaneous/i-g8mdZS3/A[/img]

I wouldn't worry about why it's trying to run up at the moment. Could be a stuck button or it could just be close enough to a dz switch to want to level up.

It sounds like the up contactor coil is bad. Did you ohm it out? Compared to the down coil? Shorted to ground? It's best to use a megger if you have one. But from what you said it definitely would be surprising if it wasn't the coil. The fact everything else comes on with no issues when the coils disconnected and also its mechanically free and most importantly runs the motor when pushed in.

I would get the coil voltage and dimensions and start searching for something that will work. Maybe check the Adam's catalouge, working on this old stuff you just need a coil that's very close. Even if it says it's for an Otis or something else.

Very important.. do not under any circumstances replace that with a modern contactor. It can only be repaired or replaced with another carbon block contactor. Carbon block contactors cant weld shut. Modern metal contact contactors will weld shut. That old stuff has absolutely nothing protecting you or anyone else if a contactor were to weld and the car will run until the power is pulled or a fuse blows.

Thank you very much for your response.
Great information about the contactor.
I won't be the one making the actual repair on this, I was just trying to help troubleshoot for them and helped them find the main disconnect for it. I work on a lot of things but not elevators and wouldn't feel completely comfortable working on it beyond replacing a fuse or correcting issues with incoming power unless it was obvious. Once I got to the point of deciding that the power and motor/mechanics were fine, I was curious about the coil and instant Up command. Looking down the shaft, it looks like there are plates for possible position switches, but this elevator is all manual. They hold the up or down button until it gets where they want to stop then release it to stop.

CJ Anderson has the coils.

Thank you EElevator for the comment about the carbon block contactors. Very interesting point.