Good electrical grounding of your K40 laser is critical to correct and consistent operation. While grounding is a safety feature with respect to dangerous voltages, this article focuses on effective grounding for the K40's low voltage DC circuit. Please consult other resources to ensure that your K40 is completely safe.
Due to the linkage to safety, please check the laws in your area - you may need to hire a qualified person to perform the work below.
- Turn off your K40's power off and disconnect the power lead
- Check that the grounding wire is making proper contact with the K40's metal case. Do this by identifying the grounding (earth) point circled in red in the photos below. There are reports that some K40's used PLASTIC washers between the green/yellow grounding wire and the case, which is completely unsatisfactory. The wire, washer, bolt and case must all be in electrical contact. Check the ground connection looks right and tighten up any looseness in the nut/bolt/connection.
With your K40 still unplugged from the wall, set your multimeter to measure Resistance, and place probes on the earth pin of your K40's power lead (green/yellow wire), and any exposed (unpainted) metal on the case of your K40 (other than the bolt shown in the above photo). Your multimeter should indicate very low resistance (eg. under 10 ohms).
- With your K40 still unplugged from the wall, check that your K40's power supply is properly attached to your K40's case. It should be firmly screwed in position, not just sitting on top of the case. It needs to be properly grounded.