Leadwell w/Mitsubishi control won't change tools - help!

I have a 1995 Leadwell V40 with a Meldas M50 control.

It was running fine yesterday... today I load a part in and start the program - the first thing it does is a tool change. The machine moves the Z axis all the way up... the spindle orients... the tool changer moves over... then it just stops. The next step *should* be that the tool unclamps... then the Z moves up higher, the carousel rotates, then the Z axis comes down, the tool clamps, then the carousel moves back. But it stops just before the tool is supposed to unclamp.

I can't figure out what is wrong. There is no error message on the screen. I have tried doing a tool change in the MDI and it does the same thing. I can move the table fine, I can move the Z axis fine. All axes home perfectly. If I push the tool unclamp button, the tool comes in and goes out fine. Everything seems to be working but it won't change tools.

I was poking around in the control and I noticed program #9001 is called "TOOL CHANGE MACRO". The contents of this program are:

G4;
T#20;
G4 P.200;
IF [#1000 EQ1] GOTO4;
IF [#1001 EQ1] GOTO4;
M66;
G80;
#131 = #4003;
#130 = #4006;
G91 G28 Z0;
G49;
N1 IF [#1002 EQ0] GOTO1;
G30 Z0 P2;
N2 IF [#1003 EQ0] GOTO2;
G28 Z0;
G#131;
G#130;
N3 IF [#1004 EQ0] GOTO3;
N4 M67;
M99;
%

I am not getting any alarms on the servo amps either.

I did notice that if I click on the command menu to show the current program, the cursor is flashing on the "N1 IF [#1002 EQ0] GOTO1;" line. I honestly don't know what that macro really does - I recognize some of the G codes but that's about it.


Any ideas? I am hoping this is something simple. Of course, I have customers screaming for parts that I can't make :(

Thanks!
Mike

For anyone that comes upon this thread later, I got it fixed.

Turns out the sensor which detects that the drawbar is down was not actuating all the way... took the covers off the spindle, found the sensor and adjuted it up 1mm or so and it's all set.

The macro program is the process the machine uses to change tools, and it is just a linear series of events. The variables are the values of various sensors, so the line

N1 IF [#1002 EQ0] GOTO1;

basically just says "wait until variable 1002 is not zero", in other words, sit and wait (while the drawbar is moving down) until it's completed moving down and the down sensor actuates.


I also want to send a thank you to Campat machine tools in Dallas, TX. I called them up and they were happy to walk me through the troubleshooting to figure out what is wrong and it didn't cost a penny. I have no connection with them other than having bought some parts in the past.


Mike

this machine has Meldas 300 controls and i lost the macro for the tool changer if anyone could please help!