bklein

Saw used one on CL with extra batteries $2500 obo. LA area.

I’d be interested in one of these if for sale cheap. Fixing component level with no schematic is challenging...

I’d take a variable dc bench supply and see if attached to the charging input, the battery might show signs of charging with it. Start low voltage and start increasing while looking at the current. Don’t go over .5 Amp for any long period of time. If you leave the detector on to drain the cells, one may have dropped under 3V and refuse to charge. You then have to manually charge it the above way to get it above 3V, then switch to the charger to continue charging. If you can’t get at the cells you may be stuck.

I’m a sick individual that enjoys the challenge of repairing a unit like this if I get it cheap enough. I spent months repairing a GP Extreme with a blown front end I got for $500 several years ago. I found someone in Australia that was a super great help. I am talking repairing a board with no schematics and just relying on years of working on stuff to find sources of intermittents and bad components with little idea of what the replacement part might be. So if you have a GPX closet queen I’d love to have a chance buying it or trade one of my many detectors for it (preferred approach). I’m happy with my GP Extreme - even got a second one I couldn’t turn down. I run one with a Beach Hog Bigfoot type coil and another with a mono coil. I use a Bluetooth transmitter for audio on one and two 18650 cells in Fatshark housing. I have several coils to use, gotten from eBay, but I don’t go desert hunting anymore - just beach hunting for me. I haven’t seen any ads for non-working Minelab detectors. Don’t know why you guys don’t post something. I don’t do repairs. I only take on one of these if it is worth it to me. To have a GPX-5000 would awesome. I might even try desert or mother load areas again if I had one.

Did you try several coils on the GPX at the beach? Curious which you liked best - mono or DD. I got a BeachHog from Rick and its really nice on my GP Extreme. Great coverage and as deep as you care to dig. Great to pinpoint the target too.

I think many of you 60+ Guys will get the harness. Just ask CTX hunters - and you’ll probably be using bigger coils than it’s 11”. Just a big coil on a stick is still mass you have to move repetitively and it’s going to get your elbow or forearm.

There was some Russian outfit that would take your sacrificial coil and make an adapter box for the CTX allowing any coil you wanted. Anyone have the link? Maybe they are doing it for the Equinox too?

Jeez. I have been and have bought two such coils from him already! That makes 3 for me, plus I may try making my own for one of my surf pi’s. Would love one for the CTX or Equinox but probably will never happen.

I replaced the buck converter with a buck boost. I also replaced the batteries with better cells. Has worked fine since. The Beach Hog is awesome. Use the fuel gauge on the Fatshark to monitor cell voltage does not get below 3V/cell.

I agree that a detector should handle overloads but it seems the GP Extreme has a history of front ends frying. Maybe from changing coils under power?

I took a Fatshark battery pack that holds two 18650 li-ion cells and fed it into a buck converter adjusted to 6.86V output and used it to power my GP Extreme. I'm testing out a (TDI) Beach Hog coil at the beach. I have a Barrie Johnson Nuggettfinder MKII that has its own speaker/amp as well as speaker/phones volume controls. The buck converter has less than a volt dropout so it has a reasonable life of about an hour and a half. I did run into a problem though - if the coil got too near my scoop the detector overloaded. Something, the audio amp, the detector, I don't know which, overloaded and went into a low frequency oscillation. I thought I had fried the detector inputs but I shut everything down, waited a bit, and repowered and everything was fine. I can't duplicate the issue using an input signal from a signal generator into the Nuggettfinder - which has me scared now. It happened twice in the latter part of the battery life so maybe this is a factor? Is the GP Extreme designed to take overloads from large metal or is it at risk of frying? I bought mine with fried inputs and fixed it - don't want to do that again. I may move to a buck boost converter, put a 2S battery management circuit on the pack, and use larger 26650 cells which would keep the voltage stable and last longer.

I’m with you guys on the steep slope beaches in south OC. Seems to me targets just aren’t there like they used to be. Used to hit big patches of them. Very risky now to get near where the good stuff probably is - where the waves crash. Even some of the one or two foot tall surges are so fast they have knocked me over. Good luck trying to hear the results of tweaking some delay setting or minute coil position with these waves coming at you. Good luck getting more than one effective scoop dig without it filling back in as well. I’m beginning to think we need a super powered pi with all the guts in the shaft and a super deep scoop. Maybe make the scoop plastic so we can scan it onsite.

Maybe try some experiments that might give more clues: 1. Walk to an area where you can try with control pod above water and then below water to see if water contact of the control pod is the key. 2. Are there any exposed metal on the connectors that could temporarily be wrapped with silicone tape or similar to isolate from water contact? 3. Flip the detector so coil is up but still in water and pod is down. Stable? 4. Disconnect coil from shaft and stretch out coil cable. Attach coil temporarily to wood or pvc pipe and see if any different. 5. Submerge the whole detector in the salt kiddie pool sideways and see if its characteristics with targets or ferrous material change.

Seems like the recognized limit is 140’ F so it should be ok.

Wow, 131 degrees is pretty hot for a consumer product. Does it vary with TX frequency/pulse settings?

Got a link to find out about it?

I see somewhere little magnets are sold to create the buttons.

Arrghhhh!! Stock of EBL 18650 3000mA cells appears to have dried up. Walmart, Ebay, Amazon... out of stock. Suggested alternate? I gave up driving around the vaping shops.

The version shown above appears to be the flat top type. Aren't they intended for spot welded tabs? Will they make good contact inline in a tube?

The EBLs appear in button top and flat top. Any difference in protection features. Flat top mainly for packs using metal strapping? There is a cell the vape shops are selling for $10 each that is quite big. I should have gotten it’s details.

Anyone checked out a couple of these? https://www.ebay.com/itm/Mobile-Power-Bank-Case-26650-Battery-Holder-With-USB-Interface-For-Bike-Light/312829220805?epid=20023749936&hash=item48d61317c5:g:h~0AAOSw2H1dvUB1

I bought a beach hog wide coil from Rick a year or two back to try with my GP Extremes. Haven’t gotten around to it yet. Other hobbies and desire to hunt with the CTX have delayed my GP experiments. Does work ok in the garage... I want to cover the control box with a plastic bag kind of thing so no added weight. Don’t need to mess with settings it seems.

I was rather shocked when I visited the local vape shops to buy 18650’s last Black Friday. Seems they have some kind of approval for that use now (and everyone was out of the high capacity cells). Looking online proved different too. Must be difficult/expensive to ship. Then came the tv ads inferring that using these cells will end in a flash fire. Lipo packs for RC use are still available for sale from hobby shops online, but many of the local hobby shops vanished - even before the virus. Anyone know more about 18650’s for vaping and what the “certification” for them infers? I’m thinking it may be for high run current but what would that be? They custom label many of them. Recommendations?

I think there is another aspect to this - if you don’t like hunting with it is there something wrong with it? I bought my CTX used but with warranty. Had problems with it, sent in for repair, fixed coil and gps. Liked it, got the 17” coil everyone was liking. It had issues, sent it back got another. It was better but the 11” is better for me. Then the EQ800 came out. I waited for the forum talk/hype to subside and got one. Used it for 8 months and just didn’t like it. Always wondered if I got a bad one. Went back to the CTX and immediately loved it again. Sold the EQ800 but always wonder if mine was a poor example. So if you like using the detector keep it as the next one you get may not be as good.