Here's some useful information about Otis 8200KA push buttons. I had to dig pretty deeply and there was a lot of misinformation online. I finally found a really old Unitec catalog and a schematic I drew back in the 90s that clarified it for me. Hope it helps some of you guys.

8200KA1 - pc board, 28v, with 1 incand. lamp with jumper on JW1, hall button only
8200KA2 - pc board, 28v, with 1 incand. lamp without jumper on JW1, car button only
8200KA3 - pc board with 1 orange LED with jumper, hall button only
8200KA4 - pc board with 1 orange LED w/o jumper, car button only
Important note: The KA1 and KA2 are identical except for the JW1 jumper. Likewise, the KA3 and KA4 are identical except for the jumper. If you install a KA1 or KA3 (with jumper J1) in the car it can damage the microprocessor. If you install a KA2 or KA4 (no jumper), I think the light will not work. In my experience, JW2 is always present on all of these Otis buttons.

By the way, Mathis Electronics has a replacement board that can replace all 4 of these boards.

Interesting. One question I had was if remote stations and serial comms were used with the hall buttons on new 401 installs. They did with LRV-3 and LRV-4 but was not sure if they released the technology for the 401 units.


By the time OTIS released the E311, everything went serial connection to the ring car boards and no more independent group controller since each RCB can become group dispatcher. Other thing done which was clever was using the switchover module so you have full power redundancy in the hall power. It's still done this way and is a very good design in my opinion

LRV-3 & 4 uses tones like a phone for hall call registration. There is a tone tester for these jobs also. The modem is located in the COP.

As someone who made the simple mistake of fitting a ka1 where shouldnof used a Ka2, trust me it WILL damage the processor. Also you cant buy them anymore so repair only. Always check for that jumper!

Now that is some archaic technology, telephone tones! Wasn't there a time when you could make a certain frequency tone and you could get free calls with a pay phone? This was before my time, but I've heard about it. Mark Wozniak former of Apple Computer found the toy whistles you would get with Captain Crunch cereal would make the exact tone for a 25 cent call. He was shown this trick from his friend John Draper.

they didn't use serial for hall buttons on any these. The only serial comm used on the older hydros was duplex communication between COP processors on two car groups on some versions of that vintage.

i'd order a whole truck load of buttons if they were cereal ! especially capn crunch ! mmmmmmm.

sorry. it was just too obvious. i couldnt help myself.