Minelab GPX4500 tips, settings, questions

I have a technical question to ask , please .

This maybe something to do with the halo effect , but i`m still trying to get to the bottom of what happened on sunday with the GPX4500 using the standard 10 " mono coil .
As mentioned in the old blokes thread on sunday , I got a target next to a test hole and it turned out to be a hot rock and then i got another faint signal within a foot of the first one and Mark and i spent 2 hours or so digging a nearly one metre deep hole which was around 2 feet by 1 feet in diameter . The signal was repeatable everytime i stuck the detector in the hole at varying intervals while digging. It got stronger as we dug deeper and then disappeared.

Mark`s SDC2300 and my pinpointer would not pick up the signal.

The dirt consisted mainly of clay and some red soil ,but not much gravel. There was a tree root about 2 feet down that was the thickness of your arm.
I had the RX gain on about 9 and the Stab on about 7 ( I think ) . I was in fixed ground balance , general search mode and normal timing. When I did the initial autotune it went out to about 205 and I left it at that.

With the SDC and pinpointer turned off and all of our gear ,including the picks sitting about 1 to 2 metres away we used the shovel and pick and plastic scoop to dig and clean the hole.

We dug with a pick ,at first and then used a shovel to dig straight down ,making a square hole . The signal was on one side of the hole and seemed to be either in the bottom under the tree root or in the side of the hole.
Once we dug the side wall out on one side ,the signal disappeared . I ran the pinpointer around the hole and got a good signal in one spot on the remaining wall ,but then it disappeared without moving the pinpointer. Very strange.

I put it down to hot soil ,but I am wondering if 2 things may have happened . With the settings I mentioned above , was the pulse induction sending signals from the hot soil that got stronger the deeper we got and it was falsing or did the small metal ring on the shaft holding the bungee cord get picked up in the enclosed area of the hole and that is really what set the detector off ?

Remember, I had this repeatable signal ontop of the ground before I even started digging and only lost it when we took the wall of the hole out.

We checked the dirt we took out and re-checked the hole with both detectors before we filled the hole in.
Could we have tipped something like a coin or gold on it`s thin side and the signal was so faint ,it was hard to pick up ?

Got me stumped.

Any input is much appreciated .

Thanks .

FOZ

I should have said the soil had sand,red soil and clay ,but not much gravel.

Your main issue will be because you are running in normal. There are not many areas (especially when there is red clay) that you can run normal. Most of the time I run enhanced.
You will have been picking up the red oxides in the clay. Sometimes if you do a ground balance over the spoil you remove from the hole you might be able to cancel it out but its unlikely when using the normal timings.
Sometimes in normal, tree roots will also set it off due to the moisture content compared to the surrounding soil.

Thanks, Steelphase.

You hit the nail on the head. I remember now that i started the day in enhance and changed it to normal .

Beginner`s error and inexperience.

Moisture in the treeroots didn`t occur to me ,but the red soil was ringing alarm bells .

Your input and advice is much appreciated.

Thankyou .

FOZ

I was very interested to read Araratgold talking about the GPX 4500 with the 17 x 13 evo coil being almost as good as the GPZ 7000 . I was going to buy the Zed but after reading what Rick had to say about the 4500 with the evo coil i may need to take another look at the GPX 4500. Anybody out there had similar results with these two detectors?

I did a depth test using my 4500 with a 19" evolution coil, against the 19" coil on my 7000. I used a 26 mm lead ball, which weighed 100 grams. I drilled a hole with a 28 mm drill so as not to disturb the surrounding soil/mineralisation. I detected around the test area with both detectors to gain the best settings on each, then I placed the lead ball on a piece of string into the hole. Using the Z I kept lowering the ball until the signal was just audible. I put a rock on the string to hold it in place, then ran the 4500 over the target. The signal was exactly the same! So, if you're looking for deeper, larger gold, the 4500 is just as good as the 7000. wiley coyote.

I was there when old mate had a nice sound usin the Z with 14 inch coil, his 2 mates swung there 4500 with 15# nugget finder and a 5000 with 18# nugget finder coils. They changed settins couple of times, still nuthin. Old mate dug a 24 inch deep hole and ended up with a 7 ounce chunk of gold. Was enough to get me thinkin, sell me 4500 and get the Z. So earley january 2020 i will buy the Z.

Great thread from people who know the 4500

Read the whole thread - learning much. Also reading through the manual and re-reading.

At this stage im still getting familiar with my setup on the 4500 but have learnt that there is no singular setup that suits all.
Pretty much each new location requires its own setup or tweak and what works in one location may not in the next necessarily.

But overall I think im starting to get the feel of this 4500. slowly.

Had a very noisy day at Whroo (Vic) a few days ago. Lots of hot rocks....kept a few. good to test with I think.
After about 5 hours my settings were all kinda messed up......though in retrospect every outing is making me more familiar -
Not a wasted experience if I learn from it and absorb the lessons n adapt. already am.....

So with my test nugget, hot rocks and the manual, plus 'tips n tricks notes' - my next outing will be back to Reef Hills to do nothing but tests.

ive now a better understanding of Ground Balance, RX Gain, Stability, Threshold and Tuning.
Early days but will see how it goes..........

Gonna get this baby purring and then ill be on track....
erfect:

Anyone had a problem with no sound coming through the speaker?
Happened to me a few months back. Tested with headphones and it worked ok. so I purchased a new speaker and all was well for a while.

Yesterday I went out about 6 and the problem reoccured.
I don't have headphones to test with.
Tried factory reset but no go.

Anyway. Probs drop it of at Miners Den tomorrow.

Just checking in to see if anyone has experienced this before.

Sounds like it's probably the amp in the battery to me.

https://www.detectronicsaustralia.com/

Give mick a call,he will sort you out in no time at all,I recently sent him my gpx battery for a repack as the battery was no longer holding charge, awesome service,I am pretty sure he is on here but cant remember his username

Mick, aka AuMan on here
good bloke, top service :Y:

Thanks All. I'm in Bendigo tomorrow so I'll drop it in to Miners Den.
I think it may still be under warranty.
Trying to find receipt in my emails now.

Ded Driver said:

Mick, aka AuMan on here
good bloke, top service :Y:

Click to expand...

Yeah thats him,just couldnt think of it,cheers

Hey all. Dropped into Miners Den today. Mines out of warranty.
We tried a cable from the battery to control box. Seemed to fix the problem.
But this has been intermittent so I'm still not convinced. Purchased a new cable.
Only chance I have is going for a test soonish as it will be too hot next few days.
Not sure if I'm going out as I'm being a lazy slob.
If this doesn't fix it . I'll contact Auman.

Hard Luck said:

Hey all. Dropped into Miners Den today. Mines out of warranty.
We tried a cable from the battery to control box. Seemed to fix the problem.
But this has been intermittent so I'm still not convinced. Purchased a new cable.
Only chance I have is going for a test soonish as it will be too hot next few days.
Not sure if I'm going out as I'm being a lazy slob.
If this doesn't fix it . I'll contact Auman.

Click to expand...

If you are any good with a soldering iron these cables are easily fixed. The wires are quite small and tend to snap right on the plug where it gets the most stress. I was advised to carry a spare curly cable and I do but I've repaired mine in the field a couple of times. Mine gets an intermittent signal before it packs it in as well but I'm told that the intermittent connection can ruin your amplifier in the battery so fix it asap when it happens.

Thanks for the advice MB but I am not very handy.
At this stage I purchased a new cable but have not been out to test it. Heck, I've been so slack I haven't even taken it out of the packaging yet.
I don't like detecting much in the warm weather.
But I do suspect it's more than just a cable problem.
Time will tell.

If you are getting sound from the headphones but not from the inbuilt speaker, it could be the headphone socket switch.
This switch passes or bypassed the internal speaker when the headphones are plugged in.
A common problem if moisture or dirt get into the socket, when the headphone jack is remove either the contact has oxidised or has a bit of lint or dirt in there keeping the contact open preventing audio being sent to the internal speaker when un-plugged.

I have inserted 2 pictures depicting 2 of many variants of headphone sockets, some are simple like the first picture showing a mono Jack, when inserted the tip contact is pushed back opening the circuit to the 3rd tab that would send the audio signal to the internal speaker.



This picture shows you a more complex socket with multiple switch options for both stereo and mono sockets.
This socket has the standard switch options on contacts 3 and 5 for stereo as well as an isolated momentary DPST switch.

Thanks Decoy. I'll probably get some one to look at it.

It will be the amp in the battery. Very common issue. I actually sell the kits to repair them ( https://www.steelphase.com.au/index.php/front-page/spare-parts/gpx-battery-audio-repair-kit ) or you can send it to me and I can fix it for you ( https://www.steelphase.com.au/index.php/blog/services ).

regards
Pat