In a perfect world all manufacturers of Geophysical Instruments & Software would provide operating manuals that were easy to follow, easy to understand and complete. This would make geophysical equipment rental and usage easier for all. Those of us who have worked in the real world know that is seldom the case. Missing steps, obscure instructions, hidden instructions and a host of other missteps can lead to frustration in operating instruments and sometime contribute to their failure and/or downtime in the field. Geonic EM61- MK2 is a good example.

Those of you who have operated geophysical equipment such as a Geonics EM61-MK2 know that on the top of the electronics box there is there is a button” labeled “on/off”. It is, in fact, not a switch but a circuit breaker. To turn the instrument on you push the breaker in, and off by pulling it out. A circuit breaker is not designed to be used several hundred times and it is an absolute certainty that if it is used in this way it will eventually fall apart. We have a box full of them if you’d like to see what a broken circuit breaker looks like.

They aren’t hard to replace, but the failure seldom occurs in our shop. Generally the failure occurs in the field and shuts the survey down until the electronics are repaired or replaced. Despite being labeled as On/Off, Geonics has told us that the circuit breaker is not supposed to be the On/Off switch. On the bottom of the electronics unit there is a switch marked M/ S that can be and should be used as the on/off switch. Incidentally the M does not stand for multiple units nor the S for single unit; it stands for Master/Slave. For a single unit the switch has to be in the M or Master position for it to operate. I might
add that none of this information can be found in Geonics operating manual.

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