Fixing an older metal detector

[tundrawolf]

Hi,


This is a very basic one knob metal detector that was given to me when I was a child, it has sentimental value to me.

It is a Whites Coinmaster TR

Recently i've begun to grow interested in prospecting and metal detecting so I dug it out but discovered the detecting disc had broken.

My question: it appears as if there is a thin conductive layer (the black) on the inside of the bottom pad, that has metallic tape and a wire soldered onto it, that appears to be cracked and dried up.

I believe this thin metal film is needed to work properly, so I can't just glue it back together.

Can I use tin foil as a replacement (why didn't they just use tin foil? is tin foil too thick?)

Or, do I have to figure out another solution?

Any help is appreciated, thanks

 

[afpilot64]

I would buy one from ebay and cannibalize the parts

 

[spence]

Hi,


This is a very basic one knob metal detector that was given to me when I was a child, it has sentimental value to me.

It is a Whites Coinmaster TR

Recently i've begun to grow interested in prospecting and metal detecting so I dug it out but discovered the detecting disc had broken.

My question: it appears as if there is a thin conductive layer (the black) on the inside of the bottom pad, that has metallic tape and a wire soldered onto it, that appears to be cracked and dried up.

I believe this thin metal film is needed to work properly, so I can't just glue it back together.

Can I use tin foil as a replacement (why didn't they just use tin foil? is tin foil too thick?)

Or, do I have to figure out another solution?

Any help is appreciated, thanks





View attachment 609423View attachment 609424

Does it function ? To me that just looks like a broken skid plate. The hot glue is just to hold wires of the coil fast and stop vibration or movement of the coil wire.

 

[MasonDixonMding]

Welcome from Maryland
I wish you luck fixing your machine.

 

[HungryGhost]

 

[tundrawolf]

I would buy one from ebay and cannibalize the parts

I considered this, but the conductive glazing would likely be just as dried up. iirc the detector did not work that well when I put it up and the dried conductive sheet might have been why. I will probably try tin foil and making a new pad

 

[GroundSweeper]

I would start with just gluing it back together - maybe find a plastic frisbee or something you can use as a new bottom to glue it too. You can buy conductive copper tape if you think that is a necessary part of it. But I would start with gluing it to a new base plastic and testing. If you get issues, work from there.

I wouldn't bother with the foil or sheathing until you test it just glued back together first.

If you get issues, you can try something like this over the cracked area only.

https://www.amazon.com/dp/B07N33FPF8

 

[airbornebob]

You can download the manual here:

https://garrett.com/sites/default/files/pdf/2020-12/Coinmaster_1_TR_en.pdf

Centerville Electronics is authorized to do repairs on all Whites (which was bought out by Garrett): https://centrevilleelectronics.net/informationl.htm

 

[Carl-NC]

My question: it appears as if there is a thin conductive layer (the black) on the inside of the bottom pad, that has metallic tape and a wire soldered onto it, that appears to be cracked and dried up.

I believe this thin metal film is needed to work properly, so I can't just glue it back together.

Can I use tin foil as a replacement (why didn't they just use tin foil? is tin foil too thick?)

The conductive layer is a carbon shield paint. You can't use foil, it's too conductive and will overload the detector. First thing I would do is glue the plastic back together. It's probably ABS so get some ABS cement and cut a disc of scrap ABS to put inside for reinforcement. Then see if you can get the detector working. If so, consider buying or making some shield paint. I use MG Chemical 839 carbon paint. Pricey though, so you might consider making some by adding powdered carbon to some paint.

 

[tundrawolf]

The conductive layer is a carbon shield paint. You can't use foil, it's too conductive and will overload the detector. First thing I would do is glue the plastic back together. It's probably ABS so get some ABS cement and cut a disc of scrap ABS to put inside for reinforcement. Then see if you can get the detector working. If so, consider buying or making some shield paint. I use MG Chemical 839 carbon paint. Pricey though, so you might consider making some by adding powdered carbon to some paint.

This is what I came here for. Thank you.

From what I know, I can get conductive carbon from motor brushes (They are relatively soft, easy to crush up... Perhaps placing them in a blende ro high speed mixer with some high quality glue...)

I appreciate the word about the foil- i was considering the foil this morning, but now I know better.

I looked up the MG chemical, the price is not bad. As I said- this detector is sentimental to me. Right now I am feeling the lag in economy and really struggling financially, this may be the only metal detector I have for a while.

Eventually, I want a Minelab Gold Monster 1000, as I have been watching videos on it and have been learning the sound.

Thank you!

 

[Kansashunter]

It is a project.

 

[tundrawolf]

this one suggests graphite instead of carbon

 

[Carl-NC]

Same thing, graphite is carbon.

 

[tundrawolf]

Same thing, graphite is carbon.

I have a question, is the carbon shield used to isolate ambient frequencies say such as from buried power lines? what if I am only detecting in the desert, away from all that?

 

[tundrawolf]

Same thing, graphite is carbon.

another question, in researching it seems as if substituting iron oxide for graphite makes the shield more conductive. However the detector detects iron, if I substituted iron oxide for graphite, would it affect the detectors ability to function?

 

[Carl-NC]

Don't use iron oxide, it will distort the TX field and reduce depth. Shielding reduces incoming EMI and also isolates the coil from external capacitive effects. Commonly this is wet grass falsing but also electrostatic build-up in dry conditions. For desert use I would shield both the top and bottom of the housing, dry wind can also cause static build-up.

 

[tundrawolf]

Don't use iron oxide, it will distort the TX field and reduce depth. Shielding reduces incoming EMI and also isolates the coil from external capacitive effects. Commonly this is wet grass falsing but also electrostatic build-up in dry conditions. For desert use I would shield both the top and bottom of the housing, dry wind can also cause static build-up.

thank you!

 

[Twisted Bones]

Wish I had the dimensions for the housing. I'd 3D print you a new one out of ASA. My only limitation is the diameter. Is there any way you can get info and pics to see what we can come up with?

 

[TexasDigs]

Check out DetectorMods channel on Youtube. He does modifications to the Minelab GPX mostly and makes coils as well. He has talked ablut the coating and wire needed for coils and what it is for. Good luck restoring your detector.