Fisher F2 Ground balance mod

[Kbron2000]

I just order my 10K Potentiometer I want to try Just Bought my NEL Tornado coil and if I can get this ground balance going I'll have a Great Machine...

[yourvibes]

f 2

hope this works . . first time be gentle http://youtu.be/blANq0yjkKw

[Kbron2000]

hope this works . . first time be gentle http://youtu.be/blANq0yjkKw

How do you ground balance? can you post a vid?

[yourvibes]

f2

hi i'd say its still auto balancing but with only the power im giving it ( someone with some knowledge could explain this alot better than i could ,,, but im a newbie to modding stuff / very new ),, turned fully clockwise gets much better results probably about 3 inchs difference from full anti clockwise and as i said the display numbers have changed a bit . let me know how the coil gets on. . ps im still yet to get out on the field with it due to weather but maybe this weekend cant wait

the mod is very simple check out the other f2 post photos look for the 20 ohm resistor ( bottom right of pic )( blue resistor ) remove it and put your pot in its place


maybe mods could merge threads

[mashersmasher]

How did you pop it open! It looks like it's assembled very similar to my bounty hunter discovery 1100

EDIT: found the pics and the 1100 is pretty much the same assembly style

[lucir82]

Hi,
Any news on the GB mod? Any other forum user did this(except yourvibes)? I am curious about the success rate of the mod.
Thanx

[BADBAJA]

Joined the forum just for this thread. Just wondering if I were to get a pot at radio shack which tolerance would I need? Anyone get a part number?

I have some highly mineralized beaches I would like to see if a GB could help with.

[Sean_Goddard]

I suspect the reason your numbers have changed is because you have changed the "angle" between the I and Q channels (Ground and Disc). Unless they are EXACTLY 90 degrees (or whatever the difference in "phase" is between the two sampling pulses for the demodulators, Yes, you HAVE indeed ground balanced your machine, but at the expense of less accurate discrimination (at least the relationship between what the display shows and what the target really is at any rate).

I would think the designers used a fixed resistor for price as a SOT (Select On Test). When the machines are made, the PCB will be fitted in a jig with a POT (probably electronic controlled) in place of the resistor. The test program then goes through the range until it finds the closest to ideal and shows a value which is then soldered in place. Pot = $0.50, Fixed res=$0.02!

ALL these "bottom end" machines are made as cheaply as possible. Fisher (or Bounty Hunter as they now are) are no exception.

If it's auto ground balancing, why do you want to manually set it anyhow (unless you need an offest)? Sorry to sound like a Jonah but I don't think the way you are doing this is the right one for this particular machine.

[BADBAJA]

I am just trying to get mine to run for my son. We have highly mineralized beaches here along the Columbia.

I do nOt use discrimination when hunting

[Skippy]

I don't think the fixed resistor's value is important, they just used a small value resistor as a zero-ohm link. It might possibly be representative of the minimum end-resistance of the pot, if it were fitted. There is a seperate master ground-balance pot to set the zero phase. The reason the target ID's change is because the microcontroller is unaware of the GB pot setting, it performs the same ID calculation regardless. If consistent ID value is important for the kind of hunt you're doing, set the GB pot for neutral-ground.
Badbaja: I don't really think this machine is suited to a highly-mineralised beach, with or without GB.

[Sean_Goddard]

I have to agree with Skippy on this one.

Your best bet would be a PI if you are not interested in Disc. The Surfmaster kits Silverdog does are EXCELLENT if built correctly.

[brudulje]

want to try out that battery mod

now done. . many thanks for that. . been running mine from 12 v converyted from old drill . .lost power gauge but seems alot more perky !

how did you wire the battery to the machine? no extra components? so you have raised the voltage to 12?
its almost no snow left in northern norway, so im starting to get my gear ready for detecting =) ordered me a nel tornado too =)

[yourvibes]

I used an old cordless makita drill that i cut the handle / battery compartment from . And then taped to top of md . . Really well balanced too . Soldered wires to contact points inside handle then wired to battery points in md.. . . Very worth while i think and saves a lot of cash/clad . . . The batteries i use are the makita 12 v . 1.3 Ah they charge in under 1 hour . . . It still works very well and i still use it . Tho not as much as used to as i now have an ex11 . . . The only drawback is that i losed the battery gauge . . I change he battery after a couple of hours or when it starts to become erratic.and i think its more perky too. . . . Let me know how the coil goes

[yourvibes]

If you need a pic let me know . . Although it was pretty straight forward . . Hope it helps

[brudulje]

If you need a pic let me know . . Although it was pretty straight forward . . Hope it helps

thanks for the quick answer =) one last question; did you wire the contact plates from the two original batteries in parallel to the new battery? so that it delivers 12v to all 4 connection plates?