Tachometer problem on THC

[awegner]

I'm new to all this.PROBLEM: Hypertherm 1250 THC height sensor not working..however, apparently after calling company and trying a few things with them it was determined that the THC tachometer is shot...
Anyone have any experience with this??

[adbuch]

What kind of table, and what kind of thc? Which company did you call?
David

[awegner]

Table and THC is a C&G Systems, Challenger but from the 90's running Burny 10 LCD Plus. During the set-up checking procedures: the fast and slow control both go the same speed - fast. When checking the thc, the torch drops to the plate and jumps up like 4 inches when height pierce knob is set to .3, when knob is set to zero it jumps up to 2 inches.
When torch is on and plasma is set to test cut, the program starts torch taps metal and jumps too high (2 in), fires but doesn't go down to a cutting position and loses arc...when we manually adjust it after program starts, it will run but then jumps...
Motor is Dynetic Systems - DC Servo Motor - Part No. 516064 B; Rated Volts 36.

[adbuch]

Does your setup use ohmic sensing to detect the material surface? If yes, then it is possible that you have a small piece of slag stuck between the shield and nozzle which could cause a false condition and cause your torch to continue raising up until it detects a "clear the material" or open circuit condition. Otherwise I would suspect a problem with your thc unit. If the manufacturer has diagnosed it as a faulty thc tachometer and this is a part you can order and install yourself - that would probably be your best bet. Otherwise consider sending your thc in for repair.
David

[awegner]

Thank you for helping. I think that replacing the tachometer would be the easiest as that is what was diagnosed the problem...the motor runs fine. If THC is not being used, the Plasma Cutter will run fine but it's a pain manually watching it while cutting and adjusting. Where can a tachometer be ordered? Does it have to have specific specs?

[awegner]

Here is a picture of the DC Servo Motor.