21 UCL need help

Hi I have a duplex 21 ucl control, one car is fine, the problem car-parks at 2nd landing and only answers a down hall call. Once you're in the car it goes anywhere you want, top to bottom non stop, but without any car call it will stop at every landing in the down direction normally cycling the doors until it reaches its parking floor. Pie plate selector, no pcb on top. Cleaned all floor bar contacts but can't seem to make the problem stop. Prints not great. I need help been in the industry more than 25 years never saw this before. Anybody have any ideas?

Had a problem similar to this before. It was a stuck relay (happens a lot on those old things) it was in the center area. TA maybe? I'm just going off my terrible memory.

Thanks. I'll take a look

Go through your hook circuit.

Hi. I've heard this term before. Can you please tell me what exactly is the hook circuit. What contacts make it up. I should've also posted that the tags on the selector are so faded you can't really read them anymore. So if you could say for example the third set from the right that might help.

Thanks

All selector contacts are clean and good. Dhs is not stuck or picking to stop the car. Anybody have any ideas?

FH bad contact possibly- Hook Circuit
FDC is mounted on moving panel (Advancing Panel) sounds like loosing direction in the up XU or LU dropping out causing lift to go straight to the top and not stopping, could be a broken selector flex wire.

Thanks for the info. However I meant to say that the unit travels normally in up direction. If taken to top landing, then it stops at every landing in the down direction without a demand until it reaches the parking floor than it holds a down direction and will only answer a down hall call.

Could be loosing XD or LD causing lift to stop every floor until arriving at main lobby Terminal C41 which is terminal feeding FDC rocking contact on advancer panel then to XD and LD coil

High speed Down contact not making. This will be the contact that keeps you from slowing down and stopping . Could be a bad shunt on the contact.