Miprom 21 40 and 41 errors.

Sometime this week I am going to look at an intermittent issue a fellow tech ia having with a 200fpm car. It shuts down after a few weeks of running fine. Errors are first and second speed boards. He has changed both boards and replaced the bifurcate relays and it still does it. Never been one to think about it before I get there but the building is not a pleasant one to go into. Looking for a lead before I get there.

If you have a Miprom Black Book, have you followed all the notes when replacing the Boards?

A 200 fpm car has only a 150fpm switch and a 90% sw. wich should pick close to 180fpm. Make sure BJ-1 on the relay interface is in the 200fpm below position. The TSF and BSF switch's on the rail should be at 17 inches from the floor level. Actually I have found they work better slightly closer to the floor, around 16 " is good. If they are too far out away from the floor they interfere with the normal slowdown profile. Good Luck.

And speaking of those terminal switches...check them. The contacts gouge and pit, and resistance increases by switch design giving false signal blips.