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Seeing that I have got out of the metal detecting busness. I thought I would pass this on to you all.
Be very carefull unsoldering the componets. Distroying the circuit traces is very easy to do.
Remove VR1 Trimmer off the board. Replace with a 50k linear taper, single turn potentiometer.
Remove VR4 trimmer off the board replacing it with a 100k linear taper, single turn potentiometer.
Mount these potentiometer’s externally on the top of the case.
Replace resistor R24 with a 2.2 Meg. You could have either a 470k or a 1.5 Meg there depending on when the unit was manufactured.
Check resistor R7. If it’s not a 51 ohm resistor, replace it with one of that value. It’s most likely a 100 ohm from factory. Later manufactured units had 51 ohms.
For potentiometer wiring, I use flat multi wire such as type used in computers for component connection to the board. I cut a 2 wire, 7.5” piece for the 50k ground balance pot, and a 3 wire 7.5” one for the 100k threshold pot. I secure these wires with a wire tie to the head phone & speaker wire near the connectors. I used one other wire tie to secure the pot wires together up near the pots.
Caution. Be sure that the pot closest to the end of the case doesn’t short out against the installed board components.
S.A.T changes. R32 220k resistor can be changed out. Raising the value slows the SAT. I have been installing a 375k running it through a toggle switch with the 220k. Giving a high & low setting of the SAT. One could use a potentiometer for variable results.
If your detector uses a ID meter, open the meter case, and replace resistor R28 (3.9 meg) with a 10 meg resistor. This aids in increasing the meter response depth.
Be very carefull unsoldering the componets. Distroying the circuit traces is very easy to do.
Remove VR1 Trimmer off the board. Replace with a 50k linear taper, single turn potentiometer.
Remove VR4 trimmer off the board replacing it with a 100k linear taper, single turn potentiometer.
Mount these potentiometer’s externally on the top of the case.
Replace resistor R24 with a 2.2 Meg. You could have either a 470k or a 1.5 Meg there depending on when the unit was manufactured.
Check resistor R7. If it’s not a 51 ohm resistor, replace it with one of that value. It’s most likely a 100 ohm from factory. Later manufactured units had 51 ohms.
For potentiometer wiring, I use flat multi wire such as type used in computers for component connection to the board. I cut a 2 wire, 7.5” piece for the 50k ground balance pot, and a 3 wire 7.5” one for the 100k threshold pot. I secure these wires with a wire tie to the head phone & speaker wire near the connectors. I used one other wire tie to secure the pot wires together up near the pots.
Caution. Be sure that the pot closest to the end of the case doesn’t short out against the installed board components.
S.A.T changes. R32 220k resistor can be changed out. Raising the value slows the SAT. I have been installing a 375k running it through a toggle switch with the 220k. Giving a high & low setting of the SAT. One could use a potentiometer for variable results.
If your detector uses a ID meter, open the meter case, and replace resistor R28 (3.9 meg) with a 10 meg resistor. This aids in increasing the meter response depth.
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