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There are images and a basic description following on how to install a handle ground balance button on a GP series Minelab detector, to make it similar to a GP3500 in operation. The image at the left shows a push button switch, a mono audio socket (3.2mm) and a plug to suit. I used some small co-axial wire (2 wires) for the connection between the handle and the plug. |
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The first one of these I did was my own GP3000 as I found it inconvenient to ground balance with the switch position on the box. This one is going on a GP Extreme and the handle at left is an old GPX4500 one that the button died in. This makes it easy as the hole is already there to accept the new switch, but the original handle is fine if you want to drill it similar to the image. |
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The image beside is a close up of the socket. The jack fits in from the left, the tag to the top is used for one connection as is the tag at the bottom right. The tag at the top right is cut off flush and not used in this instance. The 2 tags to the right actually connect together when the jack is removed and that doesn't suit this application, hence the removal of the one not needed. |
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A wire is soldered to each of the push button switch terminals and the assembly is fitted into the handle. The nut on the switch is used to hold it in tight and a dab of silicon (not pictured) is used on the wire just below the switch to hold it firm, before the foam handle is refitted along with the top of the hand retaining strap. |
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This shows the handle assembly re-assembled and ready for the jack to be soldered on. |
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A hole to suit the socket (5.8mm in this case) is carefully drilled through the front panel from the foil side, and the foil trimmed back slightly so it doesn't contact the metal parts of the socket. I situated this hole 16mm down from the outside edge at the top and 18mm in from the side. This allows this socket to clear everything inside although other types might need to have these measurements re-assessed.
The ground balance switch is the red one just above the coil connector. I unsoldered the 2 wires from it and removed the heatshrink. I attached an additional wire to each (orange and yellow) and resoldered them to the switch. These additional wires then solder one to each of the remaining tags on the socket.
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The jack is fitted to the handle wiring once the length is determined, and then it plugs into the socket we just added. The finished article is below. |
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The original ground balance switch is "open" in the Fixed position, and "closed" in the Tracking position. If we leave this switch in Fixed (open) we can control the Fixed/Tracking function with the red button. Holding this red button in then puts us in Tracking mode and releasing it puts us back to Fixed.
To detect in Fixed we leave the original switch in Fixed and control ground balancing with the red button when needed.
To detect in tracking we set the original switch in Tracking.
If we suspect there is a problem with the button then disconnecting the jack from the socket returns the detector to normal.
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