colombo973 Posted January 1, 2008 Report Share Posted January 1, 2008 Hello everybody,I have a problem on my minelab XT18000 : when i turn it on, the sound is very erratic, with long staccato. If i deconnect the coil cable, i have a régular signal so i suspect the coil to be defectuous. Is there a way to check the coil with a multimeter ? I want to be sure the coil is dead before to buy another one.Thank you by advance for all your advices. Quote Link to comment Share on other sites More sharing options...
FlakMagnet Posted January 1, 2008 Report Share Posted January 1, 2008 You've probably done this, but just in case.If you have a coil cover,did you check that there is no dirt that's gotten trapped in it?Hope it's not serious,Flak Quote Link to comment Share on other sites More sharing options...
Admin nuggethunting Posted January 2, 2008 Admin Report Share Posted January 2, 2008 Hello Colombo973, Without another coil to try, it's tough to diagnose. However, take Flak's advice and remove the coil cover and clean the coil and cover off real well. Sometimes if a small fragment of metal or even some black sands it can cause the detector to go nuts! I'm sure you checked all connections, but make sure they are hand tight and not loose. Loose connections can also cause a machine to make a lot of noise. I would also remove the battery, check the connections and give it another whirl. Did you happen to get the stuff I sent you? Talk with you soon,Rob Allison Quote Link to comment Share on other sites More sharing options...
Nuggetdigger Posted January 2, 2008 Report Share Posted January 2, 2008 i had that happen with a gold bug II one time. it got some black sand in the coil cover, and that sucker drove me crazy until i figured it out. Quote Link to comment Share on other sites More sharing options...
colombo973 Posted January 2, 2008 Author Report Share Posted January 2, 2008 Hi friends,I already done all you said. A friend tell me that if the coil is near a big metal item such a car, it can burn the coil, is it right ?Rob, i'm still waiting the pocket rocket, i think i will receive it next week.But, with the stock battery, my SD2200v2 is very impressive, in only five days, i've picked up 2.8 oz in 11 nuggets. Now, as you know, i'm looking for a larger coil for it.Flak & Rob, thank you for your help !Richard Quote Link to comment Share on other sites More sharing options...
Admin nuggethunting Posted January 3, 2008 Admin Report Share Posted January 3, 2008 Hello Richard, You should receive the Coiltek Pocket Rocket system anytime. This system will make your SD2200 more stable and you will get a bit more depth and sensitivity due to this. The weight is unbelievable, you will see! Haven't heard back from you on the coil. Let me know when you get some free time. P.S. 2.8 ounces in 11 nuggets! What was the biggest piece, solid or specimens? Congrats. Talk with you soon,Rob Allison Quote Link to comment Share on other sites More sharing options...
colombo973 Posted January 3, 2008 Author Report Share Posted January 3, 2008 Hi Rob,I found an other one today, so here is a pict of my 12 nuggets i've found in six days.Regards,Richard Quote Link to comment Share on other sites More sharing options...
Reg Posted January 4, 2008 Report Share Posted January 4, 2008 Hi Richard,You can check the resistance of the windings of your coil which can tell you something about the coil but it doesn't tell all. If you can check the inductance, that would help also. Ok, here is what to expect at least for the elliptical coil used on the XT 18000. The resistance between pins 1 and 2 you should read about 46 ohm. The inductance is about 2.3 mh. This is the receive coil. You should read about 3.5 ohm across pins 3 and 4 and the inductance is 250 uh. These measurements were taken with my LCR meter. My cheap digital measured about 3 ohms instead of 3.5 and 40 ohm instead of 46. So, as long as the resistances are reasonably close, I doubt the coil is bad (unless the problem is with the shielding or wiring). The easiest way to read these pins is to get a 4 pin chassis connector and read the back of that with the coil plug connected to it. You should NOT read anything between the two coil windings. This means, there should be no connection between pins 1 or 2 and pins 3 or 4. I normally do not recommend people take their detectors apart, but if you feel confident, you might open up the unit very carefully and make sure all connectors are fully in place. I had one come partially apart and that caused problems on my XT.Now, when you ran into the problems with the detector, under what conditions did it give you the odd signals. Was it sitting still? Did it take bumping the coil to cause the problem? The coil inductance and resistance can be good, but if the connection to the shielding inside the housing goes bad, then you can get a lot of static when the coil bumps something. When this happens, one can try to take the coil apart, but it is tough to do Since they are glued quite well using a similar liquid as the housing which causes more of a weld than a glue. However, if one is careful, you can cut the halves apart and inspect the coil. Normally, the shielding is a piece of paper with a conductive coating that is taped to a form that houses the windings. A thin wire is taped to the paper and solders to the shield wiring of the coil. If this wire breaks, then the coil can become quite noisy. I have only had this happen on one coil and that was because it came apart by itself. It was a different brand that didn't glue the halves together at the time. One final note, the wiring at the coil plug can fail also, so that can be checked to assure it hasn't been broken or pulled apart. Usually, this happens if the coil has been snagged several times when using a hip or chest mount, but can happen while on the shaft also. If you determine for sure the coil is bad and are planning on tossing it, please let me know. I would like to cut it open and take a peak inside before it goes to the trash.Reg Quote Link to comment Share on other sites More sharing options...
grubstake Posted January 4, 2008 Report Share Posted January 4, 2008 Reg, I have a Wallaby DD, last time I used it, it was just going nuts, I had totake it off and use another coil. My fault, I left the coil, before this happened in a clear plastic box in the sun on the back of my three wheeler. It got so hot in that box, it accually bubbled the plastic on the coil housing. I figured the sheilding had come un=glued from the coil and was moving inside the coil housing , making it go nuts. So tonight, I drilled 4 holes, two on the top and two on the bottom of the coil housing, just through the platic, not any farther. and used some of that expanding foam spray into the coil top and bottom. I figured it might fix it, I have nothing to lose as the coil was to bad to use anyway. So tomarrow, I'll put it on and try it out. Before it was eratic all the time, from the time you turned it on. So I'll post on how it does, tomarrow. I hope it was a quick easy fix. And the shielding won't move around. Grubstake Quote Link to comment Share on other sites More sharing options...
Reg Posted January 4, 2008 Report Share Posted January 4, 2008 Hi Grubstake,As long as the shielding connection hasn't come loose, your fix should work providing you didn't get into any of the wiring with the drill. The coil I took apart I got from Shep didn't show anyting but the shielding was both warped and loose in places, once I had it completely torn apart. Unfortunately, I had to take it down to nothing to find out for sure, so there was no going back.Keep us posted if your fix works ok. The down side of this fix of filling with foam is once that foam is in place, it doesn't let go. So, taking it apart is no longer an option.You are right about what can happen with coils if left in the sun or even in a vehicle during hot weather. People should keep this in mind when going out hunting. Somewhere I wrote a recommendation that a person should only carry the coils they are sure they will use and any spares should be placed where they won't get excessively hot. Many years ago I had a conversation with Jack Gifford (Tesoro owner) who told me he had to heat cure the epoxy he used to assure that the windings wouldn't soften if the coil was left in a car during warm weather. He wasn't using quite the same shielding technique so that wasn't a problem. However, his coils were more likely to have problems because of slight movements of the windings since they are much more critical on VLF's than on PI's. Now, most PI manufacturers do use a technique of shielding that can or at least, could at one time, fail because of excessive heat or maybe heat and moisture. Reg Quote Link to comment Share on other sites More sharing options...
grubstake Posted January 4, 2008 Report Share Posted January 4, 2008 I'm sure I didn't get into the wires, and I'm going to know tomarrow if the fix worked. If it did, then I've gained a coil back, if it did not, then I haven't lost anything, it was already a loss. Grubstake Quote Link to comment Share on other sites More sharing options...
colombo973 Posted January 5, 2008 Author Report Share Posted January 5, 2008 Req, thank you very much for your help. I will check all pins this weekend.Today i turn it on several times, and after 10 or 20 seconds of eratic beep, it seems to work pretty well . When i unplug the headphone, the speaker don't work, i have to turn it off/on to hear something thru the speaker. Another strange thing, i can't hear any threshold (full clockwise) with the speaker, but i hear it clearly with the headphone. I start to believe that the control box is ill. Quote Link to comment Share on other sites More sharing options...
grubstake Posted January 5, 2008 Report Share Posted January 5, 2008 Tried my coil fix out today, seems to have worked, the coil is nice and stable and now does not false, but is sens. You just never know until you try. Grubstake Quote Link to comment Share on other sites More sharing options...
FlakMagnet Posted January 5, 2008 Report Share Posted January 5, 2008 Fingers crossed Grubstake...Flak Quote Link to comment Share on other sites More sharing options...
rexb Posted January 5, 2008 Report Share Posted January 5, 2008 Sorry to hear that about the xt18000, if it has the problem with and without headphones and you've already ground balanced it, you're not near metal, and you've checked the coil cover, I would think there is some problem that may require servicing, it could be loose connections, the coil, etc. Nice gold by the way...is that xt18000 gold or sd2200? Quote Link to comment Share on other sites More sharing options...
colombo973 Posted January 6, 2008 Author Report Share Posted January 6, 2008 Sorry to hear that about the xt18000, if it has the problem with and without headphones and you've already ground balanced it, you're not near metal, and you've checked the coil cover, I would think there is some problem that may require servicing, it could be loose connections, the coil, etc. Nice gold by the way...is that xt18000 gold or sd2200?Don't worry Rex, in four month, i have used it intensively and is not dead. Tomorrow, i will hunt with it and my SD2200. All the nuggets were caught by the SD. But i want to say that the XT is a pretty good detector, and give a good signal on 90% of SD's signals. Quote Link to comment Share on other sites More sharing options...
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