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phrunt

T2 Circuit Board Wire Question And Possible Emi Upgrade

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So there was a rattle inside my T2 when swinging it so I popped it open to have a look what the rattle was.  It was a loose black wire,  I can't see anywhere it was meant to be soldered on, the wire is stripped at the end but no visible signs it was ever soldered anywhere.

t2board.jpg.d34e98dbdc630f6e3915b4b84a5ea02a.jpg

This is a photo of a T2 board I found on the web, I've marked the black wire with the Red circle showing the wire in question.

There is some hot glue on the back of the control box case that looks like it could possibly be the location where the end of the wire is meant to be, maybe it was just hot glued onto the control housing? 

The T2 is working perfectly with this wire not connected to anything, it's damn lucky it didn't hit something and short it while it was floating loose inside the control box.

It's not worth sending the T2 overseas for this to be fixed and it's out of warranty now anyway, especially seeing it's working fine so I was hoping someone knew what this wire is for and where it's meant to be connected to.  I think I'm right it was just hot glued to the case but I'd like to know for sure.   I also have no idea why it would be there like that, like an antenna?

Also, The T2 is a bit of a pain with EMI, has anyone considered or used EMI reducing coatings on housing to calm down emi?  I've always known they existed but never tried one so it would be good to hear from someone who has had experience with them.

This is the one I think might be the best, but there is also EMI reducing tapes and the more traditional metal with holes in it method.

Super Shield Conductive Coating - 12 oz. aerosol

Reduce or eliminate EMI / RFI interference in plastic electronic enclosures. An excellent general purpose EMI / RFI shielding spray. Protects sensitive electronic devices from electromagnetic interference. Ideal for use on plastic electronic enclosures.

https://www.circuitspecialists.com/841-340g.html

Could also do it the dodgy way and stick tin foil onto the inside of the plastic housing 🙂

It would work, if you wrap your mobile phone in tin foil and try calling it, the phone won’t have any signal. These radio waves are a form of EMF radiation. The tin foil acts as a barrier and completely blocks those waves.

Thanks in advance for any help.

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Never mind, shortly after posting I found a photo on a Russian website showing the wire and where it connects to and it was just glued onto the housing, odd... I still wonder what it's for

img_2210-jpg.2004876

https://reibert.info/threads/kloni-teknetics-t2-viking-goldfinder-i-t-p.345457/page-5

The mystery remains, but at least I know what to do with the wire now 🙂

 

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Initially I was thinking  it may be some form of ground but since the housing is plastic that probably isn’t the case.  May be some form of antenna that works with the DST tech in some type of noise canceling????

Great times to be alive when it comes to DIY repairs!!!  A few clicks on the old interweb and you can find a photo of most anything. 

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On 4/12/2019 at 9:15 AM, phrunt said:

Never mind, shortly after posting I found a photo on a Russian website showing the wire and where it connects to and it was just glued onto the housing, odd... I still wonder what it's for

The mystery remains, but at least I know what to do with the wire now 🙂

 

Is there no conductive coating sprayed onto the inside of the case? Going by the photos (both yours and his) there appears to be a graphite coating. A lot of those plastic case have either a foil shield glued to it or are sprayed with a graphite coating. They then glue the wire to it so it has a rf shield. If the wire comes loose then they get very noisy.

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On 4/11/2019 at 7:11 PM, phrunt said:

So there was a rattle inside my T2 when swinging it so I popped it open to have a look what the rattle was.  It was a loose black wire.

 

On 4/11/2019 at 7:11 PM, phrunt said:

Also, The T2 is a bit of a pain with EMI....

 

On 4/21/2019 at 6:35 PM, SteelPhase said:

A lot of those plastic case have either a foil shield glued to it or are sprayed with a graphite coating. They then glue the wire to it so it has a rf shield. If the wire comes loose then they get very noisy.

Simon, I'm wondering if the wire wasn't secured for a longer time before you heard the rattle.  Could your EMI problem been related to a loose (but audibly quiet) shielding connection?  All(?) detectors are susceptible to EMI at times.  I know my Fisher F75 (close relative of the Teknetics T2) sometimes has issues with EMI.  My Minelab Equinox has given me the most EMI problems of any detector when run in multifrequency.  Fortunately the Swiss Army Knife of detectors allows me to find a single frequency which isn't bothered.

 

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22 hours ago, GB_Amateur said:

Simon, I'm wondering if the wire wasn't secured for a longer time before you heard the rattle.  Could your EMI problem been related to a loose (but audibly quiet) shielding connection?

I think it's quite possible, I was down on my T2 for a while due to it's terrible EMI problems, I haven't used it since fixing the wire back in place so I'm not overly sure how much it's improved but hopefully it has!

I'd like to see a photo of the guts of a newer T2/F75 to see if they've improved the internal shielding, it looks like Steelphase is right there is some form of spray paint on the inside of the plastic, like a graphite spray they use on electric guitars to help with EMI.  I'm wondering if the newer ones have copper EMI tape inside them or something.  I will add some to mine and connect that wire to it to see if it improves things even more.

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It was standard on a lot of Fisher machines to have an electrically conductive coating on the inside of the control box with a wire attached for shielding purposes.

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Thanks guys, I've ordered this and I'll give it all another coat and reattach the wire to the new surface, see if I get any noticeable difference over the stock coating.

https://www.catmusic99.co.uk/product/shielding_paint

Claims to be better than standard graphite paint.  This is good reading too explaining it all, also why the little ground wire is there and connected to it

https://www.catmusic99.co.uk/page/guitar_shielding_faq

I've also ordered some copper EMI reduction tape and i'll experiment with both and see which works best.

My T2 is one of the old ones, not a new EMI reduced model.

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I disconnected the wire from the plastic housing again today and tested the T2, it was ratty and getting bad EMI right down to about 55 sensitivity, this is in my front yard where there is a lot of EMI anyway, I then reconnected the wire and hotglued it back to the housing as it came from the factory and I was able to run 80 sensitivity with it stable, target ID's on targets were good too so the wire most certainly does help with EMI.  I am going to use the copper foil tape first and test it and then afterwards I'll remove the tape and apply a few coats of the EMI reduction paint I've ordered and test again, then I'll apply the copper tape over the EMI paint and test again, I'm determined to reduce the EMI on my T2 🙂

With the wire back glued in place and sensitivity at 80 on the T2 using the Mars Tiger 10x13" coil I'm now getting better depth than the Gold Bug Pro on max sensitivity with the Detech Ultimate 13" coil so the T2 is back in business!  I think the wire has been loose/disconnected for some time, maybe from when I first got the T2, it could be why the previous owner sold it as it got ratty on them and they thought it was faulty.  I never knew any better.

The paint will take a week or so to get here as it's coming from the UK, the tape will be here much quicker as I was able to buy it locally.

Looks like Steelphase and Steve were right, the T2 appears to have some sort of EMI reducing paint on it's housing and the wire connecting to it is a ground wire.   I assume the more coats of the EMI paint the more effective it will be.

I popped open my Gold Bug Pro and checked and it doesn't appear to have the EMI paint, and most certainly doesn't have the ground wire, once the paint arrives I'll give the Bug a coat just because I can and see how it goes, probably won't make too much of a difference as the Bug doesn't overly have EMI issues anyway.

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10 hours ago, phrunt said:

...The tape will be here much quicker as I was able to buy it locally.

Make sure the tape has conductive adhesive.  I think both kinds are made and the non-conductive adhesive version won't help.

 

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