Minelab F1A4 Manuel de service télécharger pdf (Page 18)

F1A4 Field Service Manual – Level 1 and Level 2 Maintenance

Page 18

4.3 GROUND BALANCE TEST

Note: The F1A4 Control Box will memorise its last Ground Balance settings when

switched off then on again. If a Control Box/Coil combination has been previously

balanced to the GB Test Piece, on re-testing, a response to that hot rock will not be

heard again. The same Control Box/Coil combination must be re-balanced with a

GB Test Piece with different characteristics before re-testing. (If a suitable GB Test

Piece is not available, a piece of ferrite or local ground around the workshop may

suffice.)

While holding the Off/Search/Balance switch in the Balance

position, move the GB Test Piece up and down,

approximately 25 to 100mm from the Coil.

The F1A4 should initially detect the GB Test Piece (a change of threshold

tone will be heard) as the GB Test Piece is moved to and from the Coil. The F1A4

will then become “balanced” to it, i.e. the F1A4 threshold will remain stable as the

GB Test Piece is moved to and from the Coil.

1. Release the Off/Search/Balance switch so that it returns to the Search

position.

2. Move the GB Test Piece as described above and confirm that there is no

further response from the F1A4.

3. If a response is still heard check that there is no metal on the technician or

the GB Test Piece and repeat the test. If the F1A4 still responds to the GB

Test Piece, go to Section 5.1.3

4.4 COIL CONNECTOR TEST

Loop the coil cable and anchor against side of the control box, approximately

250mm from the coil connector. Grasp the coil cable 75mm from the coil connector

and gently turn 30 degrees side to side, listening for a change of threshold. If there

is a noticeable threshold change (ie similar in volume to test piece threshold

change), the coil connector is to be reterminated. Go to Section 6 for Coil

Retermination procedure.

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Minelab F1A4 Manuel de service Page 18