MCE

I have an old Otis job that was upgraded around 1999 with MCE controls. Two car group, eight stop traction, I believe 350fpm, MAC door operators and hoistway door gear. One of the cars intermittently shuts down at the lobby, doors closed and often traps passengers. The building engineers often mainline the car to free the trapped passenger, normally this really bothers me. At this building in particular I understand, they house recovering addicts and mentally insane individuals. I arrived at the building today, car shut down with nobody trapped. The LEDs on the flip down unit indicated "leveling sensor failure" (inactive). A fellow mechanic told me that these faults often indicate door lock issues. I burnished the shorting bar, checked pick up rollers and cleaned the door track at the problem floor. Is there anything else that I should be looking at?

Level sensor is exactly what it says. Either your up level or down level sensor isn't changing states when leaving the floor or coming into the floor. You can duplicate the fault by keeping one of those Reed switches in your selector box in the same state by jumping the ld or lu terminal hi or low and trying to run on automatic see if the fault pops up. Replace both lu and ld Reed switches problem solved.

Same failure in the same position could also be a travel cord to the sensors!!

Yep in this instance I would replace the reed switch sensors on the car and be done with it. If it isn't them, at least you know, they are ok(apart from potential trailer wire or new product failure issues). As a side note, if you think you are getting a door lock issue on the lobby doors, I tend to increase the close spring tension as the air conditioning can prevent nice and smooth door closing.

Had this same problem and replaced the tape guides, sensors and cartop pcb but in the end it was a doorlock. The car was always stuck at the same place in the hoistway though, where is your car when this happens?

It is always floor level, at the lobby. I cleaned the lock and track, checked pickups for binding and added a wrap to the somewhat weak spirator. I am going to order stationary and beak lock contacts.

I wonder...if this "level sensor fault" occurred at any other floor, would the controller shut the car down at that floor (1 or Lobby in this case), the next floor in the direction of travel or do a bottom floor demand once the error is detected? My point is, is the trouble really the bottom floor or could the above scenario be possible?

Doors closed? I "think" my problem showed a level sensor fault because as the car was starting to run, the lock bounced open for a split second after or about the same time the selector notched to the next floor but the car had not made it out of the floor it was on. Mine was a 5 stop and the car was always at 2 with the doors closed when I got there. Not saying yours is a door lock but the 2nd floor lock on this car was pitted real bad and it never happened again. Did you take the lock wires off and ohm contacts while you shake the doors?

I didn't lift any wires yet. The shorting bar and the stationary contacts don't look terrible, but not perfect either. If the problem comes back, I'll put in new contacts and get some reed switches for the tape reader.

Ran into a similar prob....I have seen the tape magnets get weak, over time ...check them ..especially near the ends ...if your reeds are real close to the ends of the magnet..this will occur intermittent..

Is this a LS-Quad or the Qute leveling unit? In either case it could be faulty reed sensors. I have seen on the LS-quad which uses and optical sensor for leveling, the IR leds get weak over time. If the car is near the very bottom or at the extreme top you can have problems. The tape gets tighter towards the bottom or top much like a guitar string so even relatively good tape guides can seem not good enough. If it is a Quad you can also make sure that little mirror on the back of the leveling unit plate is very clean.

I am not sure of the type of leveling unit. I should have mentioned that the lobby is the second landing. There have not been any call backs or shut downs at this particular building, so I haven't been back.

try mce tech support

you can also shut off this fault in the parameters as so when the fault does occur it will not shut down the car

Some of the previous responses were great, thought I would add to it...
1. CPU power supply. Always check the power supply voltage. Your 5V should be at or above 5VDC (I.E. 5.1,5.2)at the processor board terminals, and should be very stable.

2. Mash all the socketed chips on the processor boards. This has become a common practice with the older MCE boards on jobs with intermittent issues.

2. Intermittent low voltage to the inputs. Some of the landing system boards have capacitors that could be failing. You can cut all or just the related caps off the landing system board. System will function fine without them. They are typically brown rectangle style.

3. Possible failing PI/O or PCI/O board behind the processor. R&R Board. The inputs need either 5 or 0VDC to know whether there on or off. If any of them are 1.5 to 4VDC, the CPU doesn't know what to do with that info. This can be measured at the yellow chips near the center of the board. There are QR sheets out with every pin listed with the description

4. Mac door parts. The rod with the ball socket, too much play in the ball end can cause issues with the lock. The CPU sees inputs going on and off suddenly causing what seem to be bogus faults.

Thanks for all the responses, if I end up with another shutdown I have lots of things to look at.