I just got my "new to me" 96 model vtc20b with m32b control.
I saw it run a test program at the warehouse, seemed OK. I did not see it get "homed" when powered up. It was already warming up when I got there.

When it hit my floor today, I got power and air to it, powered it on, but am unable to home the y axis. Here is what I am doing:

Power on, home 1 light is on, so I hold Z+ button till z homes, X+ button till x homes, but when I hold y button the machine moves so far then I get " 103 soft limit y" alarm.

this is a traveling column machine, so the limit switch in back is in clear view and the control is alarming out when about 6 inches short of making the switch. So, how can I be hitting the soft limit?

On my old Mori lathe, the brake slips on x sometimes, so when I power up I have to do it in IPL mode, then deactivate the softlimit travel so that x can move far enough from where it drifted to get it home. Is the Mazak doing something similiar? Needing more travel in order to make it to the switch?

It wont run through a program unless homed first, so it seems the dealer that sold it was getting it to home properly, I may just be missing something simple. I dont know Mazaks at all. Any help is greatly appreciated. I need to get this thingh making chips asap.

Is it required to hold the button down? Did you try both directions in Y?

I don't have my books on the M32 anymore, but the manuals should be available on the MEAU site.
Look for the Software OT limit parameter.
If you still have a problem, phone Mitsubishi CNC Tech support in Chicago.
Al.

you have one of two problems.
#1 stuck limit switch.
#2 the machine needs to re learn the soft limit.

check switch with meter to make sure the normaly open and closed circuits still work.
If switch is good then the machine has lost it's soft limit.
The machine hits the switch and then counts revolutions to actual home..that count right now is greater than the distance to the soft limit.
There is a parameter for home.Write the current number down.
the parameter needs to be set to -999999...can't remember if it's 6 or 8 nines.
turn control off then on.
Re home the machine.
When the machine homes,then set the parameter back to original.
turn control off and on.
You will need to look in the manual to find the parameter for machine home as i don't do this very often so i don't remember the exact parameter.
That will reset the soft limit.

a soft limit is not a switch,its a limit set in the control or software,hence the name soft limit,check the manuals for resetting the soft limits,and as far as holding the button,usually you only have to push the button in the + driection and let go,the machine will move until it homes

a soft limit is not a switch,its a limit set in the control or software,hence the name soft limit,check the manuals for resetting the soft limits,and as far as holding the button,usually you only have to push the button in the + driection and let go,the machine will move until it homes

The soft limit isn't a switch,but the deceleration switch is,and thats what the machine uses to set the soft limit off of.
When you home the machine out,first you travel X Y or Z negative,then when you go positive,at some point the machine decelerates,thats when it is hitting the switch.
If that switch is defective the machine will not decelerate and has no idea whare to put home,and hits the soft limit.
If it's just a case of the machine losing the soft limit position...
By doing the procedure i described,it will allow the machine to refind home and reset the soft limit.

Also,if that switch is stuck closed,the machine will only move in the negative direction when you first turn the machine on,as it thinks it is still on the switch and needs to move negative first.

http://www.meau.com/Files/MAZ_M32_T32_HOME_POS_SET_PROC.PDF

your right about that in this case,but i own one cnc that has no limit switches at all,the soft limit is in the control
could it be hes just starting to close to the limit switch and blowing by it,my one mahcines which homes off the switches will blow by it if im too close and will alarm out
just a though,the machine was working so i find it hard to believe the switch failed during the move

your right about that in this case,but i own one cnc that has no limit switches at all,the soft limit is in the control
could it be hes just starting to close to the limit switch and blowing by it,my one mahcines which homes off the switches will blow by it if im too close and will alarm out
just a though,the machine was working so i find it hard to believe the switch failed during the move

Those switches will fail at times,not often but they do.
I doubt the move had anything to do with it unless someone bumped it when tthe machine was crated or tied down.
We have three machines with the M32 control,the machines are over 10yrs old and i've replaced about 3 switches in that time.
If you take into account all the Mazaks we have,i've replaced about 15 switches.
More times than not,the switch comes loose and just needs retightened.
The machines we have are T-plus,M-plus,M32 and the homing system is about the same on all of them.