Hi Guys,
We have an Old 1950's Otis 21 NICL lift that has a few issues and the age is clearly one of them.
Long story short, we needed to order and replace the speed governor and idler. This took about 6 to 8 weeks to come and the lift was turned off for this period.
Once the parts were replaced we went to put it back in service but it kept blowing the F5 fuse which feeds the safety circuit and car door circuit. This has since been replaced with a DC circuit breaker.
It now works but this is where our current issues start.
We found that the DZ1 and DZ2 contacts on the pie plate selector had got that hot that the springs under the contacts has welded together and crumbled to pieces. We replaced the spring and then found the cause was the shorted DO coil.
We have replaced the DO coil not knowing what resistance the coil is supposed to be as it was worn off, we have replaced with another old spare coil which is 2.2Kohms and no issues with the DZ contacts now.
Our problem now is that the lift will only run at full speed between floors when called from the hall buttons, when we try push the floor relays in the motor room they won't latch and send the lift straight into slow speed and trips the 3P (slow speed protection relay) relay unless you hold the floor relay on the whole time of travel.
We are not overly concerned with this as it will still run on full speed from the hall call buttons.
Our biggest issue is that the lift won't open the doors when it arrives at a floor. You can force the DO contactor and it will open the doors which made me think it might be the wrong coil as the magnetic force isn't enough to pull it in being such a high resistance (most I've seen for that type of coil have been 1.2 to 1.8Kohm for DO).
When on Cartop inspection you can switch the DO and DC toggle switch and it will open the car doors but only while you have a hall door open looking directly at the lift, if your on top with all doors closed the toggle switch won't do anything.
RO, SG and NT all trigger a signal for DO but neither of them pick DO with they are picked. Besides changing the coil, I'm running out of ideas so any help would be appreciated!
