LRLV intermittent shut down

Hello. I got an old 2 stop otis lrlv hydro that shuts down every day. I have yet to witness the problem. One report said they heard a buzzer going off. I found it shut down on both floors with doors closed. Recycle the power and away it goes works fine until I leave lol. I have gone over all door locks and limits and have the doors working good as I can see. I also replaced the marshmallow rollers on the switch tree because they needed it. Does any body have an ideas what this could be ?

It’s a lrv 4L 2000 Has a computer processor but my blue tool will not connect to it.. no pin connector Im going to change the black door open and close contractors next to relay board. But I don’t think that’s the problem. I cleaned all locks and limits well. I found it last buzzing on the 2nd floor when I got there with doors closed. I opened up bottom floor hall door looked up closed it and the car ran down to lower landing and shut down. It had been up on top floor buzzing over night. My first thought was problem with lower lobby hall lock since it moved after I opened it. But the contacts and door mechanics are great. Do you think it could be processor board ? Does Unitec still sell these ? Are they drop in replacements with no programming etc.. ?

Power supplies cause trouble all the time in the car panel. They use a voltage doubler circuit to get the 30 Volts and the caps go bad all tthe time, Then you get ripple and it will ruin the ram chip on the board. Ram chip is in a socket as processor is.If it's real old, the EPROM is bult into the processor an intel 8749 chip. If it's an 8749 chip the checksum should be EFC1.

Thanks rolly the date on data tag is 2000.. Does Unitec sell the processors and power supply’s still ? Is the processor with chips drop in replacement?

No Idea what they sell!! Yours is not an orig Lrv, they were much older. But they all have the same power supply issue.

You might look deeper into that bottom floor door lock. Next time you take a call on it check to see if the door lock circuit is made up. Not sure if you have hoistway access circuitry associated with the bottom floor door lock circuit. Hope you have a Merry Christmas.

Ok. Txs. Does anybody have a LRV4L print ?

i have a 5L. send me your email.

I would guess that the DZ mag switch is failing intermittently, I have actually replaced several of the plastic ones with the original brass ones I’ve salvaged from mod jobs. But usually when these fail the elevator goes to bottom floor and shuts down buzzer going on way down with please exit when jewel lit.

Check your email.

Got some more info. It’s now homing to the 2nd floor top terminal. It will go up there after completing trip to lower landing. It goes up and doors never open. Car still answers hall calls at this point. As soon as it relevels after sitting for a while or opening up manual lowering valve it then will not answer 1st floor hall call as it stays lit but you can open it up from 2nd floor and operate it from car station before cpu shuts down. . If you break the top floor hall door contact and then re make it then it will go down and open. Very strange. The one thing I did notice was it was releveling onto the top DZI magnet .. I moved that magnet up a little to avoid that . But it eventually times out I’m assuming after releveling and not answering hall call. .

If this has those modular open and close door relays, I would replace them both.

Replace all the ice cube relays on an lrv when having intermittent problems for starters.

Ok thanks. I am about to start ordering parts but I want to Try and get it right on the first parts order