Garrett ADS II coil

[Melbeta]

electrogalvanic action....

The windings are aluminium wire connected to copper wire.

Yes, my experience with electronics, and with plumbing, anytime you connect two dissimilar metals together, the law of electrogalvanic action comes into play, and you will end up with one metal eating away at the other metal, and you can have a eventual connection problem.

With plumbing, you never want one metal touching another metal, as corrosion will happen. In my house, an gas iron pipe, was touching the copper water lines, and electrogalvanic action happened, and the copper pipe was eaten out, from the inside of the water pipes to the outside surface, just because it was touching the iron gas line pipe, and I had to replace all the copper water line pipe, as it was "finger soft" to squeezing.

Each lower metal on the electroglavanic scale, drops out the higher metal on the scale, called precipitation, this was my experience on refining of metals such as gold, silver, platinum and so on. Did that too...

[mel parker]

Yes they can go bad.

The windings are aluminium wire connected to copper wire.

[Melbeta]

Ground Hog coils vs ADS coils.....

Thanks! It appears the Ground Hog coil is same type as ADS II. Although the Ground hog is a 4 pin and ADS II is 5 pin. The 5 pin goes to pin 1 and it might be a common ground connection. On the pcb only 4 wires come off connector,two black and two red.I will wait for new coil to ck this out. And...I forgot, when I was cking machine out in all metal mode a quarter bately move the needle up on the meter and sound barely increased, so RX coil might be open. Thanks again!
Pat

It is an old subject back in 2008, but I wanted to mention and clarify that Charles Garrett told me, that the Ground Hog coils can be used only on the Ground Hog machines, and the ADS coils can be used only on the ADS machines.

The ADS coils, that had 4 pin connector, you can get newer 5 pin connectors from Garrett Electronics, plus the rewire instructions, and change them over, and use them on newer Garrett metal detectors.

[Pat Forster]

I just got my used 7"coil for the Garrett ADS II and the detector works! Pins 1-4 measure 19 ohms and pin 2-3 measure 5 ohms. So looks like the transmit coil was ok and RX coil open. I also noticed on old coil a small 1/2 inch long slit in top plastic cover of bad coil. It was under water alot before that.
Pat

[Pat Forster]

Thanks! It appears the Ground Hog coil is same type as ADS II. Although the Ground hog is a 4 pin and ADS II is 5 pin. The 5 pin goes to pin 1 and it might be a common ground connection. On the pcb only 4 wires come off connector,two black and two red.I will wait for new coil to ck this out. And...I forgot, when I was cking machine out in all metal mode a quarter bately move the needle up on the meter and sound barely increased, so RX coil might be open. Thanks again!
Pat

[Qiaozhi]

Well, the only coil pins that have continuity are pins 1-4, so I suspect an open in either the TX or RX coil.....On the Garrett groundhog 1-4 is transmit and 2-3 RX. Thanks..Pat

Carl recently checked the continuity for me on a Garrett Groundhog coil.
The results were:
TX -- pins 1/4 -- R=31.64 -- L=2.37mH
RX -- pins 2/3 -- R=247 -- L=14.44mH

If this is a similar coil - and it certainly looks like pins 1/4 are the same - then the RX coil seems to be open-circuit. From your description, this does not appear to be the same as a Crossfire coil.

[Pat Forster]

Well, the only coil pins that have continuity are pins 1-4, so I suspect an open in either the TX or RX coil.....On the Garrett groundhog 1-4 is transmit and 2-3 RX. Thanks..Pat

[jimmyjiver]

Hi ..I Have The Crossfire Coil And It Reads 710k Between 1 & 3 And 710k Between 3 & 4...Thanks

[Pat Forster]

Thanks Jimmy! I cut the cable at the coil end, enough to solder it back, and ohmed out the wires for intermittents and continuity from coil to plug.No intermittents. cked the pcb for the coil connections and they are ok.Pat

[jimmyjiver]

Hi..Did You Try Soldering a New Connector On It Or Have Someone Wiggle The Wire While You Hold On To The Tester? I Show About 18 Ohms On Pin1 & 4 On My Freedom Coil...Thanks

[Pat Forster]

Well I couldn't ground balance anymore. Turning the gnd balance pot wouldnt do anything like it used to (needle stays in one spot). I forget if it could pick up anything, this was last year. But I measured the coil contacts and got around 30 ohms between pins 1 and 4 and open(infinity ) between all the other pins in any combination. I think pins 1-4 are RC or TX and pins 2 and 3 either RC orTX. Thanks for any help. I found another 7 inch coil and am waitng for it to arrive to further ck this out. Pat

[jimmyjiver]

Hi, I Doubt If Your Coil Is Bad ..I Would Check Your Connectors First...Now If You Would Of Said You Was Working Water Then It Quit ,I Would Say You Had A Crack In The Coil.. I Really Need More Details To Try And Help You Out. What's Your Machine Doing? Thanks

[Pat Forster]

What ohm readings are correct on the 5 pins for ADS II 7 inch coil? Can they go bad? Thanks. Pat