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Topic starter
30/01/2025 10:06 pm
I have an Otis 411mms and it randomly shuts down on a fire recall. It'll run for a few hours or sometimes run for weeks. Until all of a sudden, I come in and find it on the 2nd landing (primary floor) with the doors open on "phase 1 recall" while the controller displays SES. When i find it on recall, I'm able to turn on phase 2 and run it as fire recall is intended. I can also just reset it with the keyswitch or with a M151, but it will eventually go right back to recall randomly. I've replaced almost everything on it - even things that have nothing to do with the FIB board or fire recall. I've checked the keyswitch itself, I've had building personnel check and verify it isn't their smoke heads, I've replaced the batram chips, I've replaced ALL batteries in the controller, swapped out CPU board, swapped RCB. swapped SOM, replaced almost all contactors and relays, and even moved the input/output for the RSL and modules for recall on the FIB. Recently i just burned new EPROMs for the CPU, FIB, RCB, and MLB board. I'm at a lost. Any and all help is immensely appreciated.
Topic starter
30/01/2025 11:25 pm
I should also mention this is in a 4 car group. Two sets run 6 floors whereas the other two run 7 floors (these have a basement). the one I'm struggling with only has 6 floors and is the only one that I'm having issues with.
31/01/2025 4:40 am
I think I’d set up something to prove that the recall devices aren’t causing the problem. A data logger or a latching relay circuit on each of the external inputs.
31/01/2025 11:15 am
I'm pretty sure that at least one of the Phase 1 inputs is active low (0V on the input), possibly the one called EFO or EFK.
If whatever is holding that high (+24VDC) is not reliably doing that, and the software senses it is low (i.e. active) then the car will go onto Phase 1.
This could be a problem with wiring (perhaps an intermittent connection), momentary voltage dips (check power supply feeding this input's Remote Station), or loss of communication to the Remote Station (check it's not a flakey IDC style connector, run an RSL test and look at parity errors, etc.). If you are able to set up a camera watching the service tool screen (M-1-1-2 ?) where EFO, EFK and other fire-related inputs are shown, you might be lucky enough to see something glitching.
31/01/2025 8:31 pm
Loss of 24VDC or loss of Car RSL are the most common causes for this behavior.
Topic starter
28/02/2025 4:15 am
Thanks for the input, guys. I finally got to go back to the job today and took some of your suggestions into play. So the inputs on the FIB, that triggers emergency service is 120VAC. I used some monitoring relays for that and it checked out. The RSL power distribution is 12VDC. I noticed that every time it triggered an SES, my RSL to my FIB was roughly 8-9VDC. I tracked down the supply that feeds the FIB and found my CAP7 and R7 is where I lost my volts. Lo and behold, I found a loose connection from the + of my CAP. I'm assuming when that big ass contactor picks and drops it rattled that connection - sometimes a good connection, and sometimes not. I tightened it down and it has been going non-stop. Fingers crossed it stays that way
28/02/2025 6:40 am
The local otis guru by me told me a couple years back that
on the 411 controllers you need to routine all the connections, especially on all the wires that have those crimp on ferrule ends, ever 250k runs or so. I had some 411's in a hospital that were worn out and had tons of intermittent mystery problems. I went through the whole thing and id say 65% of the terminals were able to take at least 3/4 more of a turn. Probably 5-10% of the wires with the ferrule ends took 1.25-1.5 more turns. After that 99% of the mystery problems went away.
on the 411 controllers you need to routine all the connections, especially on all the wires that have those crimp on ferrule ends, ever 250k runs or so. I had some 411's in a hospital that were worn out and had tons of intermittent mystery problems. I went through the whole thing and id say 65% of the terminals were able to take at least 3/4 more of a turn. Probably 5-10% of the wires with the ferrule ends took 1.25-1.5 more turns. After that 99% of the mystery problems went away.