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Cathode MeasurementsHIGH VOLTAGES ARE PRESENT. IF YOU ARE NOT EXPERIENCED WITH HIGH VOLTAGE CIRCUITS, DO NOT ATTEMPT THIS PROCEDURE. ALL MEASUREMENTS ARE REFERENCED TO LINE VOLTAGE.
The Cathode has a direct relationship to the operation of the laser tube. Does your laser exhibited the following symptoms:
These are common signs of a failing cathode. A poor cathode can crack your laser tube. Catch this before it happens and your laser will have several remanufacture lifetimes remaining. Contrary to belief, it is not healthy for the laser tube or the system to run "flat out" with a faulty cathode. In some cases we can help you rejuvenate cathodes of low ours, Give us a call. The cathode effects tube voltage (fill pressure ). When a cathode is failing it changes the tube voltage characteristics. This in turn confuses the auto fill in the laser. Depending on the system, this can cause the tube to go high or low in pressure. The Cathode Delta measurement below can help determine this.
Cathode "Delta Current" is a measurement where-by you are measuring the AC current on the cathode prior to the start pulse and then again after the laser has started.
This is done using a clamp on ammeter clamped around one of the cathode leads as shown. Typically a water cooled laser prior to starting will show a current of 24-28 amps. Once started this current should rise or stay the same within -1 amp. You can take this measurement at various laser currents to see how the cathode holds up. IF YOUR CATHODE IS SHOWING A > -2 NEGATIVE DELTA CURRENT, SPUTTERS OR THE TUBE IS WINKING OUT. THE LASER TUBE IS IN DANGER OF CRACKING. THE CATHODE MUST BE REPLACED AND THE LASER NEEDS TO BE REMANUFACTURED.Low power due to cathode sag can be verified by a different method, Call us and we will go through the procedure with you. |
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