i have a 4 stop hydro, a 1989 LRV4 unit, that after a reset will take a call, only travel one floor, then begin buzzing the nudging buzzer immediately after opening the door at the landing. I've thoroughly ensured the safety edge is operational, relay is changing state and giving the reopen signal, but that buzzer behind the COP is howling away.

I thought maybe otis microprocessor uses that same buzzer as an output for a fault? All the i/o's on the microprocessor board appear correct. Any advice would be swell

Probably the RBI board in Machine room or the filter caps on the power supply. Two caps on Power supply and they use a voltage doubler circuit which strains the caps. Both are common problems. Power supply has been there a long time powered up.Ripple causes a lot of faults and failures.

that's interesting, I would have not thought to check the capacitors. Usually when a cap fails it will split/pop and be visually obvious or even have that distinct smell when they "cook out", none of which had been apparent while I was there troubleshooting. I'll head back and meter them out today.

thats just one way a capacitor can fail. Electrolytic capacitors dry out over time and increase in equivalent series resistance. They are by far the most common failure point of any power supply be it switching or linear. AC ripple is an indication that those largest electrolytic filter caps are failing. You may see them bulge or leak but you may not.

It’s worth saying when talking about power supply capacitors that the voltage stored on them can kill you even long after the power supply has been disconnected and if you are going to mess with them, you should carefully discharge all electrolytic capacitors.

Had this problem, watch your inputs on the micro-processor. Reed switches. First, Then all of the above, I spent months on this. Reed switch bad out the box,

Thanks for the friendly reminder. I always isolate and drain capacitors prior to work, and carry a gamut of resistors for doing so.

Safety never takes a holiday

Dear All,
we are converting sigma Otis Di2 by Aybey turkey but we are facing an issue that traction machine taking high current. A guy advised me to change its star connection to the delta connection. The problem is that how we can change star connection to delta connection. if anyone helps out we will be very thankful to you.