DMC doors cycle if it thinks a hoistway door is open at a floor it isn't at. I would clean all HW door interlocks and see if the problem goes away. Also it could have a bad curtain/Safe Edge.
#28082 - 10/30/1908:49 PMRe: DMC1 doors open / close every 20sec
[Re: Truegrit2]
1) Built up junk on door tracks at locked position. 2) Linkage from operator to car door needs looked at for loose bolts on driving arms. 3) Shorting SE or PHE cable 4) Broken limit collar...or maladjusted limits. 5) Door belt deformed on the motor sheave at full closed position. 6) Door belt walking off of big sheave near closed position.
All common stuff, but #1 is common on Dover.
Hope you have a FAST tool if it’s not a mechanical issue.
#28087 - 10/31/1912:26 AMRe: DMC1 doors open / close every 20sec
[Re: Truegrit2]