Tool changer problem

Hello, A friend of mine has an old (1984) Mori Seiki MV 45/55 and has a tool change problem. When he calls a tool change the drum just keeps spinning and does not stop at the correct or any tool pots.Can any one shed any light on his problem. Thanks in advance.

Remove sheetmetal covers and look for a short pipe with some slots in it and 3 proximity switches on a bracket that rotates when the magazine is moved. The combination of which ones are on/off tells the machine where the magazine is and coolant buildup, small chips stuck to the sensor, or a loose sensor slightly too far from the drum can cause it to lose position. Good luck.

I think Curt's description is for a machine newer than what you're asking about.

This one should have an absolute encoder mounted to the outside of the magazine-drive gearbox, silver in color, about 4" diameter with a gray cable coming out of the side. This is behind the cover that is above the hydraulic unit, the one where you can see the oil cooler through the hole. The encoder can cause this problem.

It could also be a stuck solenoid valve, which ports oil to the oil motor that indexes the magazine. If it rotates continuously in both directions, it's not a valve. Or, a stuck relay powering the valve, although this is low on the "likely" scale. It could also be the I/O board that "fires" the above relay.

You didn't say how you stop it once it starts rotating continuously, or what control is on the machine. Please don't leave out details like that, it's too hard to just guess at stuff accurately.