Vallon VMH3CS Mine Detector

[Qiaozhi]

Hi to Brian and Th'r,
You don't actually need 7 pins; 2 will do . Vallon use 7 pins to make a psuedo coax connection, i.e. the middle pin is live and all the outer ones are connected together to coax ground. I suspect that this is an emi precaution, but not relevant in civilian use. I have a 'rejected' coil and shaft where one outer pin has broken off. It works perfectly.

Eric.

Presumably Vallon make this pseudo coax connection in the plug because the housing is plastic. With metal connectors (such as those used by Whites Electronics and Minelab) I always add a bare wire from the coax to the metal housing of the plug. This allows the metal case to act as a shield. Otherwise I've noticed that touching the outside of the plug can sometimes produce a signal. This is a bit odd because you would think that the metal case of the plug would already be electrically connected to the metal socket.

[Ferric Toes]

Eric; Thanks for the Vallon manual link. Here I show an adapter for a White’s lower rod to the Vallon VMH3CS. It is made from two common home improvement store plumbing items, and requires some lathe work. There may be a 7 pin connector that could be potted in, but one could probably just use pins and wires, sealed out to a small external connector. Not ordinarily opening that joint again (by changing coils at the coil end). I used a threading die to cut a 1.5-8tpi thread on the adapter’s existing OD, though threading in a lathe would make maintaining axial alignment easier. Also, the ID on that end has to be opened up to 1.215”. The other part is a sawed off and faced pipe nipple with the existing hole drilled out to .75”. There is plenty of opportunity for further refinement.

Hi Th'r,
That is a good way of doing it and using the existing thread on the middle rod. Now you have identified the thread, I will look into that further.

My way is perhaps a bit more drastic and also requires lathe work. First is to cut off the existing connector housing and locking collar. You might think that undoing the three screws would achieve this, but the screws seem to have Threadlock applied and even if you do get them out, the body is cemented to the shaft with epoxy. Be careful not to cut through the coax. Undo the locking ring securing the hard rubber connector body in the now free outer housing. Pull the plug forward and then cut longitudinal slots in the housing to free the cable.

I can't remember the exact stages from then on, but the picture paints a thousand words. At least it shows that various parts involved and the potential to use alternative home built coils. In this instance the yellow tube contains a ferrite cored probe. The correct size pins are readily available and I plug the live one into the middle female socket and the ground one into any of the outer six. When coupled together, the pins just retract into the internal space in the yellow tube, which could alternatively be a Whites lower shaft.

The inline connector is normally on the end of the coax, but I cut it off so that I could pull the whole cable from off the bulkhead but leaving enough to rejoin later. The red and blue wires are from the battery supply. All the latter is only necessary for a full dismantling. The connector plugs into the distribution board, which is the first thing you see when opening the main box.

Oh yes, the pipe fittings are George Fischer pvc and available from RS Components. Heavy duty and O ring seal. Pvc parts are secure to the fibreglass tubing with Double Bubble epoxy resin, Pvc needs to be roughed up with sandpaper to give good adhesion.

All the above by Th'r and myself are just suggestions and ideas, and requires a certain level of mechanical expertise and use of a lathe. Refinement is ongoing and it is better to wait until full instructions emerge before attempting changes that may be irreversible.

Eric.

[Mdtoday]

Hi Eric,
If it's not too much trouble, could you post some pics of the 7 pin connectors please.
They look suspiciously like Conxall Mil-E QUAL series connectors with custom over mold.

Brian

[tifred]

Hello eric
The tape looks like this, nickel woven canvas.
A photo piece that I retrieved on a computer
,is conductive...

[Ferric Toes]

Hi Eric,
If it's not too much trouble, could you post some pics of the 7 pin connectors please.
They look suspiciously like Conxall Mil-E QUAL series connectors with custom over mold.

Brian

Hear are a couple of pictures. The two inserts appear to be the same except that one is male and the other female. The bodies are a rubber type material with an additional O ring on the shaft side. Both are held into the housing with a threaded plastic retaining ring. This is seen detached from the connector body in the smaller picture. The coiled cable goes into the telescopic shaft. The wire loop connects to the 6 outer pins which are electronics ground.

Eric.

[Mdtoday]

Interesting, thanks Eric.
Would you mind posting a pic of the socket connector front view when you get time to please Eric.
It's possible they have used a mil spec connector insert and machined it. There doesn't appear to be an over-mold.
Seeing the front view would help narrow the search.
I'll keep looking.

Brian

[roadhog]

Hi All
So i managed to get out for a couple of hours today to have a play with the Vallon VMH3CS.
So first impressions are its well built rugged piece of kit as for using it for general metal detecting ie in a farmers field looking for the elusive hammered coins i am not so sure as yet?
Iv not found a way of discriminating against iron or copper at the moment it all sounds the same to me, as for the led display still trying to work that out too.


would be handy to know if anyone out there has had some more time on this unit and could put up pictures or video to explain more.

Cheers all

[Mdtoday]

Hi roadhog,

Sounds like a good detector, I'm waiting on mine to arrive in OZ so cant help much at the moment but I will post my experience.
In the meantime, have you looked at the Vallon manual via the link that was posted earlier in this thread?
Good luck with it.

Brian

[6666]

Hi roadhog,

Sounds like a good detector, I'm waiting on mine to arrive in OZ so cant help much at the moment but I will post my experience.
In the meantime, have you looked at the Vallon manual via the link that was posted earlier in this thread?
Good luck with it.

Brian

If yours comes in a canvas bag, do not breathe the dust, the battery cap can be a bit dicky when you first insert the d cells
so switch the machine on, then slowly screw on the cap until the machine starts up, this gives you a better feel for how much
pressure the cap needs to make good contact, and how tight it should be.
The manual has a few strange comments in it and does not describe all the functions and processes fully in good english.

[Ferric Toes]

If yours comes in a canvas bag, do not breathe the dust, the battery cap can be a bit dicky when you first insert the d cells
so switch the machine on, then slowly screw on the cap until the machine starts up, this gives you a better feel for how much
pressure the cap needs to make good contact, and how tight it should be.
The manual has a few strange comments in it and does not describe all the functions and processes fully in good english.

I have found that in a few Vallons, the battery cap is very hard to engage in the threads on the battery holder. In these cases, presumably, it is because the battery tube is not set in its correct position after a service. This is probably when an arm cup has been replaced when the whole back end has to be removed. The contact end of the battery tube should protrude from the threaded collar that the battery cap screws onto by between 1 - 1.5mm; no more. Another thing that helps is to put a smear of silicone grease either on the O ring on the threaded collar, or on the smooth inside lip of the battery cap. The metal plate in the battery cap contacts the bare lip of the battery tube, so you screw it up until you feel a solid stop. You cannot over tighten. Has to be like that for the military.

Eric.

[Davor]

If you can over tighten it, you surely screwed it up

[roadhog]

Hi MdToday
Yes Thanks
The only Problem im having is The limitations on the discrimination setting and the limited tone that it gives, everything so far sounds the same but im not giving up yet, got a sneeky feeling this is very similar to the Garrett gatx and if im right this unit should be brilliant on the beach.

Go Get Them Hammerd Coins.

[jaypay]

No discrimination setting as far as I know.

[Ferric Toes]

Hi MdToday
Yes Thanks
The only Problem im having is The limitations on the discrimination setting and the limited tone that it gives, everything so far sounds the same but im not giving up yet, got a sneeky feeling this is very similar to the Garrett gatx and if im right this unit should be brilliant on the beach.

Go Get Them Hammerd Coins.

I did an air test on a 13th century silver hammered coin 18mm diameter and 0.8mm thick. It has a cross on one face, all arms the same length that goes right across the diameter both ways. You probably know the one. The Vallon will give a discernable and repeatable signal at 13in. I also tried a small bronze Roman coin., 15mm.D and 1.3mm thick. I get this at 11 - 12in.

Eric.

[roadhog]

That Interesting Eric
Was That with the standard coil does the led or tone change with differant metals as i dont seem to be able to tell at the moment?.

cheers all please all keep up the good work.

Any news on how to flash these units yet?