Home Forums General Discussion Technical Questions MphII question

Anyone know what dach and dacc stand for on a Schindler mph print . Fuse 3 feeds dach then the door control board. Dacc is on the ground side.
Keep blowing fuse 3 replaced the door control board unplugged everthing and still blew fuse but doesn't blow when not connected to board.

Not sure but I wonder if dach is the + and dacc is the -. As to the fuse blowing, it is a little weird but I wonder if you've got a dud new board(however unlikely). The fact that it doesn't blow a fuse with the board disconnected, is also weird. Is the loom going to the board from the controller to the top of car? If so I would try to run a 'test' loom(outside of ducts/existing wiring) to prove your not getting some induced voltages in it, or a short that is only apparent when connected to the pcb. Anyway some food for thought.

Dach and dacc is just the 115vac power supply to the door operator, it comes through the door switch on the controller, then to the power input of the door operator, the only other path, is that it feeds the controller board that lights the KDPO led in the controller. I believe that some of the door operators require a MDL type fuse, which is a slow blow fuse. if the board is new, try a slow blow fuse, if that does not work, put the door board switch to test, so that it is not trying to operate the door when power first comes on, you could have a bad door motor.

I thought someone else used that nomenclature as well. DACH/Door AC Hot and DACC/Door AC Common.

I'll try some things today get back to you guys

looks like dach and dacc go through a resistor and some blocking diodes then a zenor I think it's all in the main relay board just wondering if I should try replacing it. fuse three opens when I plug in the door control board with nothing else hooked up.

There are 2 plug connectors on the DCB (I'm assuming it's a DCB and not a TDC?). I'd plug each one in seperately and see if just one blows it and/or both. I would of done the same, change the board. Did you use a known good board? Did you check the door motor? A FCB is involved also..

I would still want to know if the loom going to the door board is ok. Take the board to the motor room and wire it directly there to see if the fuse blows. make a separate loom don't use the fixed one. At least doing this you prove the wiring isn't getting some sort of induced voltage or short. Maybe then the supply board might be faulty with that supply bridge you just described.

I unwired door motor and unplugged everything to door control board and still blew so I'm going to change relay control board tomorrow and see.

Sounds like your rectifier is shorted on the RMH.