spindle speed changer problem v2xt

[meanmachine85]

i have a v2xt with a speed changer that only works when it wants to. i can set a spindle rpm, enter spindle start line, and it will sometimes go to the correct speed. today it jus stayed at the last speed it was set to. has anyone had this happen? if so, what did you have to fix?

[machintek]

I know that on my Boss 9 this feature can be turned on and off. Not sure with the V2XT. Would have to find a operating manual. This is only an approximate speed as the feedback is done by a variable resistor (like a volume control). Ut is a common issue for the coupling to this device to get loose.

George

[machintek]

Also make sure your air is ON as the speed is changed by a air motor.

George

[meanmachine85]

the air is hooked up, and the speed changer works. I turned on the spindle today and pulled off the air lines and jus ran the speed changer with a blow gun running off an air dryer and the speed will adjust and the rpm on the screen does change. one thing i noticed is that the rpm readout is missing the last digit. for example: 1200 rpm just shows up as 120. Is the potentiometer the variable resistor you talked about? and the coupling is its set screw? is it common for the potentiometer to just go bad?

[machintek]

since you can use the air hose to move the air motor and adjust the speed:
Put it in low gear and watch the display as you run it through its full range. What range does it display. 60 RPM to?
Then put it in high and try the same thing.
Trying to see if the hi/low switch is recognized and if the potentiometer is working correctly.

George

[meanmachine85]

when its in low it reads 60-450. when i turn the knob to high it reads 60-450 because i just noticed today that it always says spindle lo on the screen. so could the hi/low switch be my problem or should the machine still change speed with a bad switch?

[machintek]

Ah Ha! It is not seeing the hi/low switch. If in the wrong gear electronically speaking it will not attempt to adjust speed.

George

[meanmachine85]

ok, thanks! I'll see if i can locate a high low switch then.

[machintek]

Follow the wire. It is in the metal block that the hi/low lever pin locks into.

George

[meanmachine85]

i moved the hi range switch out just a little bit and now the machine recognized it. in high range the readout reads 540-4200 rpm. it still wont adjust speed. the speed increase/decrease knob has never worked since i got the machine and i was wondering if that could be tied into the problem. the book doesn't say anything about it affecting the speed adjust, but i thought i'd run it by you.

[machintek]

I would be checking for a voltage drop across the solenoid coils when the Jog button is pressed to change spindle speeds. No voltage? Trace it back. Coils may be open or shorted. If shorted could have blown a fuse. Does the air brake work?

George

[meanmachine85]

i have 24 vdc across the speed increase and decrease solenoid coils when the button is depressed and the switch checks out also. the air brake does work.