www.machinecrt.com
Prototrak crt rebuild page
Checking your mx or age pendent
1 unplug logic cable from back of unit
2 turn on pendent you should here three beeps
And if the monitor is working you will see 9 bars 
On the screen
M series pendents
M series will beep when the cpu is fired up if it does not beep 
The cpu power supply is bad ( note we do repair that power supply too)
If it beeps and the disk drive runs you have a monitor problem.
If you have any question about your prototrak monitor feel free to give us a call