Fisher F2 Ground balance mod

[Dave J.]

I've been trying to figure out what yourvibes actually did. I think brudulje asked the right question.

My followup questions: will the smoke smell like toasted voice coil, or vaporized MOSFET? Or will the abused F2 actually survive this mistreatment?

--Dave J.

[brudulje]

I've been trying to figure out what yourvibes actually did. I think brudulje asked the right question.

My followup questions: will the smoke smell like toasted voice coil, or vaporized MOSFET? Or will the abused F2 actually survive this mistreatment?

--Dave J.

hehe, yh im trying to figure out if the F2 actually can handle the jump from 9v to 12. but from what i have gathered from yourvibes it should be ok? im waiting on an reply, i have the f2 open and i am currently adding the 10k pot for ground balance.. =) gonna use a 11.1v lipo battery if i have understood yourvibes correctly and he is putting 12v into the MD this should be fine =)

[brudulje]

fisher F2 input voltage

I think i have figured out this F2, it seems that it runs on 18v, that the two 9v batteries are in series. there is probably a voltage regulator that is regulating it down to 12 or so volts internally, and that is why it can run on the 12v battery in yourvibes case. im not 100% sure about this. but that is what i have found out after an hour or two of measuring and studying the pcb.
if you check on the picture you see the two sets of wires coming from the batteries, and you can clearly see that the positive from BC2 is connected with the negative lead from BC1, in other words in series..and i measured 18v..so i think ill just stick with the standard batteries for now. if anyone have some more input ill be happy to hear it, and thanks to everyone who contributed to this thread so far

[brudulje]

cant really seem to let the volt issue be..after some more thinking and speculation im starting to wonder if it is 18v or if it is using +9v gnd and -9v??? (like amplifiers)

i hope yourvibes or anyone else can help me out on the subject =)

[Skippy]

Correct, the 9V batteries are in series, so it runs off 18V. From memory, there's a series diode (for reverse battery protection?) then it's linear-regulated to 12V,. So the lowest supply voltage I would run it at is 14V. Might I suggest you do the obvious thing, and run it off two PP3 9V batteries like the manufacturer intended, and if cost is a problem, use rechargeable NiMH type. You can get capacities of 160 - 200mAh easily now, they last a decent number of hours.

[yourvibes]

the gurus on here are more knowledgable than me with all this modding. . . . . . but heres my F2 working fine .. not smoked, doesnt smoke . . . . . although the battery gauge doesnt work now !. . . . . heres some fotos hope they help

just a pic of detector showing battery location. . really easy to swing


wires going through detector housing. . . i suppose you could run the wires through the stem also !!


inside battery housing. . . each battery place is wired as 12 v. . . i didnt wire directly to pcb only to battery points inside housing as can be seen

i use the 12v battery from a makita drill. . . so if your going to use an 11 volt you should be well safe. . . .

[brudulje]

Correct, the 9V batteries are in series, so it runs off 18V. From memory, there's a series diode (for reverse battery protection?) then it's linear-regulated to 12V,. So the lowest supply voltage I would run it at is 14V. Might I suggest you do the obvious thing, and run it off two PP3 9V batteries like the manufacturer intended, and if cost is a problem, use rechargeable NiMH type. You can get capacities of 160 - 200mAh easily now, they last a decent number of hours.

thank you thank you for the reply! =) yh i think i will just stick to the 9v batteries for now then.
so happy i got that cleared up. yey!!

im done adding the ground balance pot and have been outside and testet it, seems to work as intended and actually balance the machine!

[yourvibes]

i

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 =)

i had an old drill and batteries just lying around and i was tired of buying 9v batteries ----- spending my new found coinage !! so the 12 v seemed a viable option as most electronics have a tolerance i didnt think that 3v would be that much of a jump -- tried it and it worked so no more buying 9v batteries for me . . but as i say the battery indicator doesnt work so maybe on its limits and i use it for full mornings/afternoons changing the battery after a couple of hours use. . or when it starts becoming erratic

[yourvibes]

heres a vid of detector. . i know in house doesnt help. . . . but it put my mind at ease !!!

http://www.youtube.com/watch?v=blANq0yjkKw

[Skippy]

[shocked smiley]

[yourvibes]

[shocked smiley]

hi skippy. . . . ( there always seemed to be a little negativity around this post right from the very begining even from the hole in the keypad ) or ( maybe just my imagination ) i dont mean to be of any offence to you or anyone else or cause any other argument and im not typing in caps so im not even shouting . . i know its supposed to run at 9v and was designed around that . . . . but i thought this site was for modding and tinkering ( detectors and coils etc ) in a friendly way . . well that is what i done and it worked and it works pretty good and if anyones around the north east england uk and would like to test it themselves they are more than welcome to come out detecting with me to test it and see for themselves .... and now for a big thankyou to anyone thats added any info or pics

to brudg hope the info works well for you too and if you get the coil upgrade could you pls let me know how good/bad it is.( i was thinking about the 8.5 x 12 hunter coil ) . . . . as i really like my f2 especially when it locks on to something the sounds are so distinctive and easy to reconise and you can use it on the wet now

[yourvibes]

TO all i would not use more than the 12 v power ( !!! i may have been lucky !!! ) !!! who knows !!!. . . . . . !!. . as can be seen in pic from Brudg. . . . UNDER RIGHT SIDE RED WIRE there is a track comming off the 9v power !!!! (i know its hard but look closely you can see it ) ( you have been warned ). . . i know you can see a track joining batterries together to make 18v but there is a 9v track comming off the single battery aswell . . . so i would not be putting a 14v or 18 v into the power input as this would be doubling up later to 28/36 and would not leave anything for the tolerances +/- so would surely blow something . . . . . . . . ( yeh i remember now thats why i soldered onto battery points inside the battery housing ) and not onto pcb

[yourvibes]

hi dave
my mistreated badly used and abused F2 works like a dream . . . not toasted not smoking and not vapourised and it still lives on pulling the finds out

and by now brudg should be trying his to great effect too

I've been trying to figure out what yourvibes actually did. I think brudulje asked the right question.

My followup questions: will the smoke smell like toasted voice coil, or vaporized MOSFET? Or will the abused F2 actually survive this mistreatment?

--Dave J.

[yourvibes]

hey brudge

hows your results on mod any improvement

[brudulje]

yh, hehe. im sorry i was wrong and you where right on the track running over the hole in the panel :P im gonna order the nel tornado 12x13 next week so that i get it around the time the last snow disappear. and yh ofc im gonna share the results with you =) oh and i think im gonna make a video soon showing ground balancing it too. and yes you may be on to something with the 9v track going of there.
cheers guys, and happy hunting!