Inside the TX-2002 pinpointer

[sinclairuser]

that would be my guess, i'm not prepared to accept that these are hand tuned individually, i checked this 3 times with different equipment, but they all read the same within the meters specs.

[mr.sneezy]

@sinclairuser
42 ohms on the coil is huge is it not ?

I suspect you're right that they stick any old ferrite coil into these and hope for the best. I bet some are surplus FM radio tuning coils or similar.

I'm about to attempt to remove the ferrite from the pointer tube. Hopefully without too much swearing

[kt315]

: Nono:: Nono:
as you say, I wonder?

why I must scan you INSIDE THE METAL DETECTOR? may be I must give you my wife, my car, my house too?

[sinclairuser]

since this thread is active again, specs of tx 2002 belonging to my customer:- 42 ohms, 3.02mh,33nf.
works out at 15942.6hz res, and 2213.41hz operating freq.
if i understand this calculator correctly, the missing components are missing on this too, i suspect that if you tested 10 of these you would get ten different coil specs, my guess is they just bung in anything.

[walkman]

you do not want DVD because DVD you got. you want Inside The Metal Detector scanned, which is copyrighted. ask George and if he will agree to send you
files I will do. if not so that is not.

: Nono:: Nono:
as you say, I wonder?

[mr.sneezy]

I'm back from some time away.
The thread's quieter than I thought it would be after all the required info was posted up.

Who's good at creating the schematics on the forum ?

Cheers,
Martin

[sinclairuser]

I can't see that a strip down would reveal much, but perhaps measuring the coil values might be useful, as well as the parts you think might be popluted on his unit.
Thanks,
Martin
PS. I intend to see if I can melt the glue around the OEM coil in boiling water and see if I can slip it out, but that will be middle of next week.

i was only thinking about the coil measurements and the unknown components, this is someone else's pinpointer after all, totally striping it would not be good practice anyway.
but in curcumstances like yours all info is helpfull.

[kt315]

kt315, I want free DVD. I send to PM

you do not want DVD because DVD you got. you want Inside The Metal Detector scanned, which is copyrighted. ask George and if he will agree to send you
files I will do. if not so that is not.

[mr.sneezy]

Thanks for answers. mr. sneezy. But, some knowledge of the components and coil Could you give value?

Hi Walkman, you can find the final (now correct) parts list with values on post #30, in PDF and XLS file type.
The coil value is in there too in the list.

Be aware that on Qiaozhi's merged picture that the unmarked rectangular component above K1 was fitted with a normal axial resistor (2k4). It might have been for a trim pot originally me thinks.

[mr.sneezy]

thanks and nice job mate, i know someone who has one of these, i'm trying to borrow it, i cant promise to "field strip" it as you have done.
but i replaced the led for him and i'm almost sure that his board is fully populated, so photos of that board and coil measurements may help a little.
if a board has missing components its always nice to know what they do.

I can't see that a strip down would reveal much, but perhaps measuring the coil values might be useful, as well as the parts you think might be popluted on his unit.
Thanks,
Martin
PS. I intend to see if I can melt the glue around the OEM coil in boiling water and see if I can slip it out, but that will be middle of next week.

[mr.sneezy]

OK - here it is.

Very nice work, that make following the tracks very easy.
We have a long holiday weekend coming here so I won't be putting the unit back together till after that. I'm packing my main detector and hoping to do some beach hunting.

[Qiaozhi]

Can you post up a saved GIMP image of this technique when you do it, be nice to see what a pro can do with GIMP.
Martin

OK - here it is.

[sinclairuser]

thanks and nice job mate, i know someone who has one of these, i'm trying to borrow it, i cant promise to "field strip" it as you have done.
but i replaced the led for him and i'm almost sure that his board is fully populated, so photos of that board and coil measurements may help a little.
if a board has missing components its always nice to know what they do.

[walkman]

Wow, impressive given the short amount of time. Yes, you have some missing tracks, but tomorrow (late) you will have HiRes images of the top and bottom faces of the bare board.

I have a plan to use a light table to backlight the bare board as well as do a regular image of each side. Backlighting really shows up thin tracks well.

Please see the final draft of the Parts List, as there are a few corrections in it now, plus 'as measured' values as all parts were removed tonight.

Looks at first glance that the 4011 is partly being used as an inverting buffer....

Martin

PS. What is the largest file size JPG image I can attach here ?

Thanks for answers. mr. sneezy. But, some knowledge of the components and coil Could you give value?

[walkman]

kt315, I want free DVD. I send to PM