Ethan M. Posted December 11, 2008 Report Share Posted December 11, 2008 Hello everyone,I'm new the the forums and metal detecting. I recently bought a Minelab GP 3500, and the detector had been working well until last night. After I set up the detector according to the instructions, I attempted to produce a target signal with a gold ring I've used for the same purpose many times now.Unfortunately, the detector, in a completely stock configuration, would not produce a target signal when the gold ring was run past the coil.Initially I assumed this was an issue with the battery because the detector did produce a slight response when I ran the coil over my aluminum scuba tanks, and I made sure the battery was fully charged to test the detector again. Despite the freshly charged stock battery, though, the detector still would not produce a target signal on nearly any metallic object, let alone the gold ring. I read in the manual that, in the event the detector will not produce a target signal but the threshold is audible, the operator should test different coils. I did so, and my 18-inch Minelab DD is working great. So, does anyone know what the problem with the stock 11-inch coil could be? Will I have to completely replace the coil, or can it be fixed? Thanks for your time and help, everyone. Quote Link to comment Share on other sites More sharing options...
adam Posted December 11, 2008 Report Share Posted December 11, 2008 I`ll just say that make sure you are not in the discriminate mode. When you are discriminating the target will blank out instead of giving a signal. Quote Link to comment Share on other sites More sharing options...
grubstake Posted December 11, 2008 Report Share Posted December 11, 2008 Make sure you have a threshold, check you coil connections, check your connector, on the coil, pull the boot back, and losin the screws pull the connector out and check to see if a wire is broken or un-soldered. Grubstake If the 11 inch dd ever had water in it, then its shot. DO NOT! EVER TURN YOUR DETECTOR ON< WITHOUT A COIL BEING ATTACHED! Quote Link to comment Share on other sites More sharing options...
DOC Posted December 11, 2008 Report Share Posted December 11, 2008 If it is not a broken wire inside the connector, then the coil is shot. They are not really repairable.Doc Quote Link to comment Share on other sites More sharing options...
Ethan M. Posted December 11, 2008 Author Report Share Posted December 11, 2008 Thank you, adam and Grubstake. Let me give you guys a little background to see if that helps.I bought the Minelab 3500 about a month ago, and I read the manual several times through before I used the detector. Right after I got the package in the mail, I checked the detector out. I made sure I could get a target signal with a gold ring, and I checked a few of the features. Everything worked fine then, right at the end of October. It has been working fine with the stock coil, until just recently.I've been slowly using the detector, checking out its features and preparing to use it in some local areas. Last weekend, I took the detector out to a test hole I've dug and I checked out every feature. By the end of the weekend, I'd verified that all of the features work, including the automatic tune function, ground balance and discrimination. Generally I've been running the detector in the fixed mode, but last weekend I messed around with the discrimination feature to make sure it was working, which it was. I have been treating the detector with kid gloves, and I've followed all the protocol in the manual. I haven't plugged the stock coil in while the power was on, I haven't unplugged the coil while the power was on, and I've never turned the detector on without a coil attached to the electronics. I haven't dropped, hit or otherwise adversely treated the coil or the detector. I haven't gotten it wet at all. Anyway, over the last few days I haven't had time to experiment with the detector, so last night I took it out to my test hole and tried to get a signal off a gold ring. I was surprised when I found I couldn't get a target signal at all. I've used the same gold ring for this purpose a hundred times, so I expected a strong signal.I checked all the settings but I could not get anything from the ring or any other metal object, no matter what mode I put the detector in. At this point, the detector was set up to be completely stock, just as I'd been using it from the moment I got it in the mail. At first I thought it was the battery, and I just bought a new stock battery as a backup, so, after fully charging my new battery, I changed to the new battery and checked again. I still couldn't get a target signal with the stock coil.I remembered reading in the manual, under the section on troubleshooting, that if you could hear threshold but no target signal, you should test a different coil. I have an 18-inch DD, which I hooked up to the detector. I got a signal right away. It seems to be working fine. I tested the 18-inch coil with the detector settings suggested in the Quick Start Instructions in the manual on page 12. What I'm wondering is, did a certain feature I tested last weekend cause a short, or otherwise adversely affect the stock coil? I am able to get threshold with the stock coil, but it will not respond to nearly any metal or produce a target signal. I can tune it, and it will verify that the auto tune function has finished running. I did get it to sound off for a second on my aluminum scuba tanks last night, but after a few passes it stopped registering a target signal. It didn't sound like it was discriminating out the signal, and discrimination was set to all metal. It just stopped reading the metal completely, like it wasn't even creating an electromagnetic field. I checked again tonight and it won't read the aluminum tanks or any other metal object.Has anyone else experienced this? It must be somewhat common, if the only suggested fix in the user's manual for a detector that produces a threshold tone but no target signal is to check a different coil.I'll be calling Minelab in the morning, but I thought I'd ask here to see if anyone has heard of this.I would appreciate anyone's thoughts. Thanks for your help. Quote Link to comment Share on other sites More sharing options...
Ethan M. Posted December 11, 2008 Author Report Share Posted December 11, 2008 If it is not a broken wire inside the connector, then the coil is shot. They are not really repairable.DocI'm kinda fuzzy on checking the wire. How can I go about removing the coil wire from the coil to see if it's broken? Are you referring to the end of the wire that connects to the control box? If so, that appears to be fine, though I'm definitely no expert.If you mean the end of the coil wire that plugs into the coil, that appears to be fastened tight to the coil. Is there a way to loosen it without damaging the coil? It seems odd that the coil could be so easily damaged. Is it common for them to just stop working? The detector has only been used for testing purposes so far, and I've been very careful with it.Thanks for your response, DOC. Quote Link to comment Share on other sites More sharing options...
grubstake Posted December 11, 2008 Report Share Posted December 11, 2008 Ethan, the end that connects to the box, this most likely the cause, pull the boot back, youwill see two screws holding the bale in the connector, remove them, the there is a small screw holding the plastic end in the connector, remove it also. then twist the plastic part and work it out, pushing the cale from the back of the metal part. as you get it out, you will see a clear plastic insulator around the soldered pins, check it for lose or broken wires, you could also have a wire broke as far back as 6 inches or so. so wiggle the cable and see if it make a difference first. More than likely its a broken wire in the connector, or a cold solder joint. If thats not it, well I'd say get new coil. Like DOC said not much can be done if its the coil. 99% of the time its a broken cable connection. You could take the coil to a TV shop and ask them to check it out. My uncle can't solder and his quit, and they olny charged him $5.00 to re-solder a new connector on. You can get them at a CB shop or Radio Shack. Grubstake Quote Link to comment Share on other sites More sharing options...
Ethan M. Posted December 11, 2008 Author Report Share Posted December 11, 2008 Thanks guys, you've been really helpful. DOC, I did as you suggested, and sure enough, one of the four wires is sheered clear off right above where the two wires connect. All of the other wires look fine.How does this happen? Is the break caused by a mechanical force, or is it an electrical short of some kind? Is it caused by a twisting of the cord? Well, it looks like I just have to re-solder a new connector back in. I'll have to take it in though, as I don't know how to solder. Maybe I should learn, though, seeing as how I've taken up a new hobby.Good advice, DOC. Thanks again for your help. Quote Link to comment Share on other sites More sharing options...
grubstake Posted December 11, 2008 Report Share Posted December 11, 2008 Ethan, its caused by the wire flexing, when you put it on and off, and also it flex's asyou detect. There is a fix for it, I use cable holders, fixed to the bottom of the handle, some use metal ones, I use nylon cable holders, like they use to fasten wires ti the car body, I remove the 2 bolts fron the handle, and put one on each bolt, in the crak in the handle, and leave one side of the holder lose, after I put my coil on and connect it, I simply puy the cable in the holders and its enoght to keep it from flexing. Less cable movement, less false signals. Grubstake I thing you got me confused with DOC. Quote Link to comment Share on other sites More sharing options...
Ethan M. Posted December 11, 2008 Author Report Share Posted December 11, 2008 Ha. Sorry about that Grubstake. I was typing too fast.That sounds like a viable fix. I'll try that as soon as I get the wire fixed. My buddy is pretty good at soldering, and I'm sure he's got some cable holders. Are most cable holders that are used to fasten wires in cars made from nylon? Are there any other tweaks you use to improve the reliability of your detector? I'm very interested in that kind of information. You just don't find this kind of stuff from the usual sources. I love message boards. Quote Link to comment Share on other sites More sharing options...
grubstake Posted December 11, 2008 Report Share Posted December 11, 2008 Most are made of nylon, but you can do a metal one, some of the guys use them, as far as other tweeks, always ground balance your detector, each time you turn it on or off, I cycle mine also with the tune button, I'm in a high interference area. after you get it ground balanced, flip to fixed, use your button on the handle to re-ground balance as needed. Don't relie on discrimination, hunt in all metal, dig all targets. don't sweep to fast, keep you coil on the ground if you can, set your level ajust to around the 1:00 mark, ajust your tone to suit your ears, and threshold so you can hear it break. Hunt in deep. you won't miss anything. Volume your choise. Good hunting. Grubstake PS don't be afraid to play around with your settings, every ground is different, and so will your settings be. Quote Link to comment Share on other sites More sharing options...
Admin nuggethunting Posted December 12, 2008 Admin Report Share Posted December 12, 2008 Hey Ethan, Welcome to the Nuggethunting Gold Forums! Great questions and glad the guys on here were able to troubleshoot the problem for you. Also, always make sure you're not in the "Cancel" mode while you're out hunting, as this will kill about half, if not more of your sensitivity and depth. You might consider one of the new Lightweight Coiltek Goldstalker coils for your new GP3500. These new coils (round and elliptical) are amazing. Hope to see you posting more in the near future.Rob Allison Quote Link to comment Share on other sites More sharing options...
DOC Posted December 12, 2008 Report Share Posted December 12, 2008 Try to remember when you wrap the coil cable around the shaft to try and arrange it so the plug lines up perfectly with the control box male plug. In other words, you don't want to end your wind up and have the plug oriented in such a way that you have to twist it to get it to align properly in order to be plugged in.Twisting the plug is a major cause of the wires being broken as well as falsing. You want that plug to easilly align and not be torqued at all.Take care!Doc Quote Link to comment Share on other sites More sharing options...
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