F3 Field Service Manual – Level 1 Maintenance
Page 9
•
Move the Ground Balance Test Piece from approximately 150mm (6ins)
above the centre of the coil slowly towards the centre of the coil, no response
should be heard.
•
If a response is still heard, repeat this procedure, if there is still a response,
go to Section 4.4 for faultfinding procedures.
b.
If local ground is being used:
•
Ensure that this procedure is carried out on ground free of metal and hold the
coil about 150mm (6 ins) above the ground.
•
Press and hold the ground balance button down for 3-4 seconds, this will
reset the detector internal ground balance setting.
•
Slowly lower and raise the coil to the ground (touching the ground), a ground
response should be heard. If a response cannot be heard from the ground,
find an area of ground that produces a response when repeating the previous
step. If no ground can be found that produces a response from the detector,
a Ground Balance Test Piece must be used (Section 2.2.4.a).
•
Press down and hold the green Ground Balance button
and slowly lower the coil directly to the ground (touching the ground) then lift
the coil up again 150mm (6ins).
•
Continue to lower and raise the coil until the ‘Ground Balance OK’ tone is
heard. (‘Ground Balance OK’ tone consists of a short high-pitched double
beep).
Note:
Movement of the coil during the entire Ground Balance procedure should be
slow, continuous and smooth and each down and up movement should take 3
to 4 seconds.
•
Release the Ground Balance button.
Figure 4 Ground Balance Procedure
•
Raise and lower the coil from the ground, no response from the ground
should be heard.
•
If the Ground Balance OK tone is not heard within 20 seconds of starting the
procedure, release the Ground Balance button and repeat this procedure.
•
If there is metal in the ground under the coil whilst Ground Balancing, the
detector will not ground balance correctly. Move the detector and repeat the
Ground Balance over ground that is free of any metallic objects.
•
If a response is still heard, repeat this procedure, if there is still a response
after repeating this procedure, go to Section 4.4 for faultfinding procedures.
