|
Why does the display show open circuit even with the probes correctly inserted?
First check that you do have the correct connections by referring to the RM4 instruction manual. For example if you are using a single 0.5m Twin and a PA5/PA20 probe array then note that the short black jump lead goes to the red socket and the green jump lead goes to the black socket. If open circuit is still shown then it is very likely that there is a break in the cabling of the probe array (in the "current" cable). You will require a multi-meter that measures continuity or resistance to trace where the break is in the probe array, flexing the cables in turn until an open circuit is found. Where possible replace the cable; cable type is not critical and any mains type cable can be used.
There are several places where the cable can break. Firstly, the cable that runs up the side of the probe array frame may be broken at the top of the frame where it exits and is held in place with a pair of cable ties. Secondly, the AD1 adapter may have a break in the short length of cable. Thirdly, the 50m cable can have a break anywhere along it's length; a break may be near the resistance meter especially if it is tied in a knot round the frame for strain relief (in this case cutting off a short length and rewiring the black Bulgin connector may isolate the problem - see appendix G in the RM15 manual for details on how to rewire a connector). Fourthly, the cables that connect from the drum to the remote probes may be broken.
Why am I having difficulty obtaining stable readings?
First check that you do have the correct connections by referring to the RM4 instruction manual. For example if you are using a single 0.5m Twin and a PA5/PA20 probe array then note that the short black jump lead goes to the red socket and the green jump lead goes to the black socket. If you still experience large fluctuations in the readings, often much higher than expected, yet the resulting plots still seem to produce some meaningful results then it is very likely that there is a break in the cabling of the probe array (in the "potential" cable). You may also find in dry weather that the meter gives very high readings when the probes gently touch the ground but if they are firmly pushed into the ground the meter then produces normal readings. Readings may also have a slow drift on them. You will require a multi-meter that measures continuity or resistance to trace where the break is in the probe array, flexing the cables in turn until an open circuit is found. Where possible replace the cable; cable type is not critical and any mains type cable can be used. See above for indications of where the break may be.
What do I do if there is water in the RM4?
If you have been working in extremely heavy or driving rain and water has entered the electronics housing of the instrument then you should not use the instrument until it has dried out thoroughly. Remove the lid and leave the instrument in a warm dry environment for at least 24 hours, preferably longer. Take great care not to damage internal wiring if you remove the lid. DO NOT OPERATE WITH MOISTURE INSIDE. If you attempt to operate the instrument with moisture inside electrolytic action could severely damage the electronics. If water is present in sufficient quantities that you need to tip it out, an environmental seal may have been damaged and the instrument ideally requires servicing. Once dried out you could continue to use the instrument temporarily, providing weather conditions have improved, and then have a servicing performed after the survey.
Why does the NiCad or NiMH battery pack not hold its charge?
The battery pack can be recharged up to approximately 600 times. After this number of recharges it will start to lose its ability to retain charge and will need replacing.
|
|
