Depends on what vintage DMR he has, the later units did have a regulator board, the older units were all relays and timers.
I have 4 Mark 5 DMR's still in operation, 21 floors with a swing car.
There have been times we have had to kill the lighting in the machine room, and throw the disconnects in, one at a time, including the dispatch panel, to look for the sparks on the controllers to find the bad relay coils.
Building owner won't spend a dime on them so he's getting eaten up in callbacks and obsolete clauses.
Too dumb to MOD.
