Home Forums General Discussion Technical Questions Door op mod Otis 7777A to Otis AT400

Gentleman, first time poster here but looks like a helpfull bunch of guys.
As the subject line says, I'm upgradeing an old otis 7777 screw drive resistance control operator to a Otis AT400. The install went fine but after wiring up everything as the cut in prints say to, no commutation between the LRV 3 controller and the AT400. Door takes and holds a learn run but that's it. Also, and I have no clue way,The car won't run on normal just car top inspection. Unitech is no help past the door operator and as this is my first one, it's driving me nuts. I would be forever grateful for any insight anyone would have. Thanks for even reading this.

First I can't believe you still have a screw drive 7777 in operation still. Second, there is no communication from the processor to the AT400. You should have the discreet wired door operator. Basic wiring should be motor voltage, control voltage, nudge command, and open/close command.

Thanks for the response. That's exactly how I understood the prints and I'm sure, how I wired it. That's why I'm baffled. We just picked this job up and also were amazed to find a 7777. I've found 4 jumpers on the relay board done by others in the past and can't figure out why they were placed there. I'll have to dig deeper on that issue as maybe their affecting the new door op. Again thanks.