Vallon VMH3CS Mine Detector

[Mdtoday]

Hi Eric.

It looks to me like you can get away with wiring another keypad onto those pads, good quality ones will have OK debounce Chinese E bay specials will be woeful.

Brian

Eric,

Maybe a good idea to check if keypad inputs to processor have ESD protection if wiring off board.
One would hope there is some form but it's hard to tell looking at the pcb in my unit.

Brian

[Mdtoday]

I've got the bug to purchase another Vallon and noticed some units still available from the UK EBay site although they do look a bit ratty.
Basically, I'm looking to design a dual purpose rod / hip mounted enclosure in the smallest footprint I can and include LI batteries, Bluetooth and design an audio mod to reduce the frequency of the sound.
The plan is also to either bypass or blank the audio output when the confidence beep occurs as just dividing the frequency by 2 gives a horrible sound. So bypassing or routing the original confidence beep around the divider circuit and blanking the divider input during that same period will still provide the original confidence beep/s but also allow the new divide by X sound.

So so that is the plan but wondering if anyone else has purchased a Vallon from this latest seller and if so are the units ok electronically?

Given, I'll be re housing I'm not fussed about appearance.

Brian

[Ferric Toes]

I've got the bug to purchase another Vallon and noticed some units still available from the UK EBay site although they do look a bit ratty.

So that is the plan but wondering if anyone else has purchased a Vallon from this latest seller and if so are the units ok electronically?

Given, I'll be re housing I'm not fussed about appearance.

Brian

See my PM.

Eric.

[daverave]

I didn't want to go this far, but the right hand switch was jammed solid and the whole display was in a poor state. As you can see, there were four layers to peal off before getting to the contacts. What seems to have happened is that some adhesive or sealant had run down and collected under the right hand button. It had the appearance of hot melt glue and it was difficult to prise the button off, but taking things slowly, it eventually came free and I cleaned up the contacts on the pcb.

It almost looks to me as though that button never worked as the wear marks that are visible on the other contacts are absent on the right hand one. The other interesting point is the number of contact buttons I removed. All of the buttons were in fact pairs, so there should be eight in the photo as I didn't discover the other until I used calipers to measure thickness, and after the photo was taken. Maybe this was to increase the pressure required to depress the switches as Vallon state that the detector can be used in up to six feet of water. More depth than that and the switches depress.

The existing layers of plastic (polycarbonate?) are unusable, so rebuilding the display/control unit is out of the question, but what I might try is wiring a 4 x1 keypad onto the existing contacts and rehousing the whole detector in a different way.

Eric.

[ATTACH]40139[/ATTACH] [ATTACH]40140[/ATTACH]

Hi Eric...Looks like a very involved task taking that key pad apart.

[Ferric Toes]

Hi Eric...Looks like a very involved task taking that key pad apart.

Ah, but look what happened after that. There is that very same keypad/bargraph but with a new decent size weatherproof key pad in a completely new design for the Vallon electronics. Li-ion batteries, standard phones, FM transmitter or Bluetooth. Total weight is just over 3lbs compared to 5.5lbs for the standard VMH3CS.

Still got to finish it off with some legend, a cover for the bargraph and a smarter knob, but I like it.

Eric.

[daverave]

Ah, but look what happened after that. There is that very same keypad/bargraph but with a new decent size weatherproof key pad in a completely new design for the Vallon electronics. Li-ion batteries, standard phones, FM transmitter or Bluetooth. Total weight is just over 3lbs compared to 5.5lbs for the standard VMH3CS.

Still got to finish it off with some legend, a cover for the bargraph and a smarter knob, but I like it.

Eric.

[ATTACH]40172[/ATTACH] [ATTACH]40174[/ATTACH]

Hi Eric...That is absolutely amazing how you have transformed the military looking vallon into a modern looking pulse detector...and got it very light weight...very nice indeed.

[Carolina]

Very smart!

[kingswood]

Thats amazing Eric!....you would not even know it was a Vallon !!!

[Mdtoday]

Now that is truly a transformation Eric, your ideas and attention to detail are amazing, well done and thanks for sharing!

Brian

[Ferric Toes]

Thanks Brian,

I had already built a belt mounted unit in this box, so it was an extension of that. I didn't much like the belt mount as it is sometimes inconvenient when digging, as the coil/shaft is on the ground but still attached. Also the display and pushbuttons are never in the right place to see properly. With this arrangement and wireless phones you are free when you put down the detector to dig deep without any restraints.

Here is a picture of the inside. It all fits snuggly into the Hammond box with little room to spare. I have a gasket for the box and O ring screws to make it fully weather and splash proof, but not fitted those at this stage. I am going to make a acrylic cover for the display as the existing slot goes straight to the display pcb.

Eric.

[Mdtoday]

Hi Eric,

That layout is tight but very well used and looks built to last.
Yes, I have been thinking on the hip mount version and its problems but haven't really come up with another reasonable solution yet.
That keypad looks nice and reliable too.

Brian

[Mdtoday]

See my PM.

Eric.

Thanks Eric, have replied to PM

Brian

[Ferric Toes]

A useful Tip

Most Vallon VMH3CS detectors that come onto the military surplus market have obviously been used in extremely dusty conditions. Everything that is not sealed has a coating of fine dust, even inside the display and control unit on the top of the handle. The main electronics housing from immediately below the display unit is sealed and tested with a vacuum in the final manufacturing process with the result that the important electronics are dust free and also watertight.

One part that suffers from long use in such dusty conditions is the telescopic shaft arrangement and particularly the knurled locking collar. The internal back surface of this collar gradually gets worn away so that the mechanism no longer locks firmly, no matter how hard you tighten the collar. What happens then is that it sticks and is a real struggle to undo. There is also no way of replacing the worn parts as everything is securely fixed by threadlocked screws and epoxy adhesive.

A solution that appears to work is to split a suitable size O ring and put it on the smaller diameter shaft either ahead or behind the split sleeve with the tapered edges. The O ring I used is 20mm ID and a cross section of 3.5mm, however I expect any size near this will work.

It is obviously a good idea to clean as much dust as possible out of the parts that lock together and also the surface of the smaller shaft. This can be done with a small brush, warm water and washing up liquid. When dry, give the thread in the locking collar a smear of silicone grease, and also both tapered surfaces of the split sleeve.

Locking the shafts at the desired length is now much more positive and smoother. Also easier to undo as the knurled collar does not stick. The only thing I have noticed is that sometimes it is necessary to unscrew the knurled collar a bit further than the two rotations that Vallon states is necessary. Keeping the surface of the internal shaft clean and polished will help in this respect.

Eric.

[Mdtoday]

Hi Eric,
Yes I can vouch for the amount of fine dust in these units, grinding away between moving parts over their life in the services would be like using sandpaper on them.
Your idea solves the problem with a reliable and simple fix

Brian

[chevesne]

http://www.geotech1.com/forums/showt...501#post233501

I do not know if it is the same, but the one I see at the moment has a failure not listed in the manual.
Any ideas?