otis 21ucl, 6850bv selector

I have an intermitten issue, this is a 4 stop duplex with basment operation. This is only happening on 1 elevator, on a down hall call the elevator will get to the floor open the doors and sit there with the doors open like is as stuck button. "Dhst "is not dropping out which leaves "xhst" up which leaves "nt" up which is what is keeping the doors open. I am having aa hard time figuring my way threw the "dhst" circuit to ground to find out what is keeping everything up. Again only happens on one of the cars, and it may run 8 to 20 times before it fails.

slimline relays? replace the dhst armature. residual magnetism is screwing with you. also, take a burnishing rubber stone to the pivot points of the armature on the relay, a little carbon dust, crud, dust makes them a little sticky sometimes.

Billvator
Do you have a print for this job? I have a print from 1958 for 10-21 & 30 UCL controller drawing # C2570152. My prints do not show relays for DHST or XHST. But I have HST.

May I suggest you check the set - reset on the landing coils. Check your floor bars DHS, DCS.

NT I would imagine is your door timing circuit. I would think if it only does it from a down hall call it's in that circuit.

Both suggestions above are spot on. Your reset circuit is very likely your issue-worn contacts on the selector can cause all kinds of weird issues

Can you hang your meter right across the reset coil, and see if it's getting a pulse, to drop it out?

hey billvator, ive never seen a controller with dhst(down hall stop) so im assuming there is a uhst too. ive only seen hst(hall stop) and cst(car stop) on the selector so this is new for me. the suggestions of residual magnetism is very true. clean the knife edge of the relays and also to prove faults you can slip a piece of paper in between the armature and stator temp. to help fault find faults too. you can get copper tops for these relays as well.

ok does the lift stop at the same level? if so then more likely the floor level call relay is sticking but if not it could be the hall call cancel brush on the selector(for the reset coil) not working properly. i would suggest when the fault occurs that firstly check for volts at the coil of dhst then work backwards. from what i remember the stopping pulses are just that pulses to set the advancer panel(and stop dogs) to set. im assuming that xhst is a aux relay bc of the need for extra contacts.

Thanks everyone for all the feedback, i will start checking into some of this again on monday. Prints=yes. Slimeline=?. I thinks the down relays set/reset is working fine because the other car is never sticks nor does the relay hold in..But i will start rechecking everything first thing monday, thanks and i will keep you posted.

Something just popped into my lil brain-I separated two cars for a mod-duplex setup. You didnt notice that one car was not canceling a hall call on one floor. The other car would pick it up. When I took out the first car for the mod the second car would go to the call and not cancel it. Being two four stop units it was never noticed with both in operation. I found that we installed a dispatching update in the early 80's and that the second car was lacking the UHST from the dispatch upgrade to the selector, only at that floor-the wire was never installed

E311<<<>>> thats why i'm glad not to be adjusting, troubleshooting or doing MOD's anymore, my brain can't take that Crap and my body can't take the stress anymore. management has no freaking clue what we go through out in the field making things right for our customers. all the care about is the mighty dollar.

If it's doing it on the main landing, check ML relay on both cars.

AND THE WINNER IS........Residual magnetism! Changed the DHST coil and cleanned everything on that relay, 2hours no issue! Thank for all the input just got wind of this sight and i can already see how useful this will be.

You may need to change the core also...

Thats one of the first things I check when I have sticking calls or while watching the car run while trouble shooting. Good find

ifrratedpilot, i polished the core with the Dremal made sure there was no burr's, also it did not show any magnetism to metal(even smacked it on the ground a couple of times).
Also do any of you know if they make a Sequences of Operation for the 6850 selector? i have maintance t.i.p.s and parts leaflets form the shop but the supv. is having problems finding a Sequences of Operation not sure if they even make one?

Hi Billvator,
On the residual magnetism, check the gap between the armature and the flat washer where the screw that holds the coil in. if there is no gap the coil will burn out again. there should be a buck out spring and plunger on armature. I have had these for years in older UCL. If you need info on 6850 selector email me I have S.E.O. of selectors. 25 years of wearing green pants has it's perks.

Do what every one else does with residual mag....stick a bit of paper in it...temp repair works for years usually as most are to damn lazy to strip and clean...or on a night call!!!...LOL

ha night call trick alright. in fact thats what was taught by the tuners!

by the way kiwi otis or boral?

elev8 need your email, i would like to get that info.