The Case of the Mysterious Servo Drive Repair

Damaged Hypertherm Servo Drive

Burnt components in Hypertherm drive

Ever wonder what happens to your servo drive when the motor is bad or there are line spikes?  Besides the obvious (it stops working) nearly every component inside gets damaged, burnt or blown to bits, often beyond recognition.  What then?

What if the part numbers are no longer visible and there are no schematics?  How do you know if this drive is repairable?  That’s when you will be glad to have an experienced repair technician on call who is one part electronics whiz and one part Sherlock Holmes.  The short answer is yes; this drive is most likely repairable and let me prove it to you.

Check out the pic of the Hypertherm servo drive that came out of a U.S.-based farm equipment manufacturing plant.  It is worse than it looks in the picture…. blown IGBT, open 3 phase bridge, old e-caps, blown resistors, blown film cap, blown TVS diode, bad opto, and PCB/trace damage for starters.  To up the challenge factor, many of the component part numbers had been obliterated.

As bad as it may seem, this kind of servo drive repair is not unusual.  The risk comes from potentially using replacement parts that are not the right value which could result in the drive still not working or, worst case, cause it to blow up again.  Some experience and a little sleuthing will get the right component part numbers to avoid this trouble.  In this case, we had a similar drive on hand with much less damage which made it fairly simple to identify the correct part numbers.  Mystery solved.

This Hyperthem drive was repaired, tested and sent back into action manufacturing farm equipment.  We are glad this manufacturer can get back to business keeping our farmers supplied with sturdy equipment.  Don’t wanna mess with our groceries!