Vallon VMH3CS Mine Detector

[hamam]

Well I have made an appointment with Vallon and paid for the firmware upgrade, I will arrive at their reception in Eningen the morning of Tuesday 10th July.

I 'll try and obtain as much info about the cable/firmware as possible, and be cheeky and ask for a tour of the facility, if you don't ask you don't get!

If anyone in the UK wants anything picking up PM me.

I'm trying to understand if the data cable is something more than just D-SUB to the MIL-spec connector.
Rocketdemon did you find out if there's some smarts in the cable?

[Little Tinker]

Hi all.
does anyone have the firmware to upgrade so I can get beach mode and loose the beep?
thanks all
T

[BC547]

When you follow this video: pay extremely good attention to the polarity of the battery tube ! (no idea how he/she distinguishes between + and - in the video)

I also have my doubts about a polarization protection diode in parallel with the battery, instead of a diode in series. Of course there is the 0.6V drop, but the detector works fine with 3.9V instead of 4.5V.
Especially for a military type of detector, I would assume it is more robust to any abuse than any other device ?

[BC547]

Just a short update on the battery mod I did on the VMH3CS.
Instead of putting in 3x D cells in series, I made up a battery tube from a 32mm drain pipe and 2 x 18650 LiIon batteries in parallel.
No protection on the batteries - charged with an external charger.
I have 2 of these tubes and I use them alternately. This went fine for 7 years, until I dropped in one of the battery tubes upside down.


Inside the VMH3CS battery tube, there is a small recess at the positive pole side, that allows for the protruding + pole of a battery to make contact, but not the flat sided negative pole.
On my quick and dirty home made tubes, both + and - connections contain a small screw, and this screw head on the negative side was sufficient to make contact to the VMH3CS positive connection.
So, a direct connection of + and - reversed batteries without current limitation, resulting in a catastrophic failure.
Post mortem analysis: across the battery connection on the signal distribution board, there is a protection diode.



Located here:



This diode is probably perfectly capable of withstanding a D-cell reverse polarity, but was no match for this uprotected LiIon bomb.

Resulting in a burnt component and part of the PCB trace:




I contacted Vallon in Germany via email and they confirmed in a friendly reply that my assumption was correct.
In the mean time I had already replaced this destroyed component with a 1N4007 diode + some wire over the burnt trace.
After this repair, the detector was working fine again.

To avoid these kind of stupid "accidents", I built a new battery tube from a cylindrical Anker powerbank.





This delivers 5V output to the detector, resulting in a very happy beep and all LEDs lit at switch-on.





I added a small "window" in the drain tube to view the 3 LEDs during charging + an external USB-C connector.
The + and - connection of the battery and the USB-C charge port were connected with the USB cord cut in 2 pieces ( USB-A and USB-C) that was included with the powerbank.
I also tested that the 5V output is short-circuit proof.

Here is the Anker tube charging via the USB C connector --- the paint job has gone terribly wrong:




Well, lesson learned: when replacing the 3D cells with an 18650 combination, add some protection around the batteries.
Or better yet: use a cheap 5V powerbank, as suggested here in the thread already on a number of occasions.

[Little Tinker]

RIP Eric.

[Little Tinker]

I must add I noticed a different behaviour that's not mention anywhere that I have read.
on huge signals where my etrac would show "overload" the vallon seems to change into pin point mode and make a different lower tone and the closer to the overload the pitch went up and the leds moved to the right.

Is this normal?
Its a nice feature but I wasn't expecting it.
On the larger plate it reads year 2011 and serial number 16859C in really great condition with both ears intact and minor scratches to a few corners.

[Little Tinker]

Thanks for all these posts, a great 4 day read with lots learnt.

[Infamy]

I don't know if this has been covered, but I saw a video from Norway where the guy using a Vallon VMH3CS said the detector had discrimination but it was turn off. Is this correct?

If you can get software updates then it must be a button sequence?

[SFi]

Hi
Someone here used an tested vmh3cs would please tell me what is the maximum depth (or air test) of this device (with standard 30x17cm coil)? Not for gold nuggets or coins; I mean about big block of metal for example 10x10x10 square cm.

[davyowens74]

Been away from the hobby for a bit and managed to lose my original profile; Really enjoying re-reading this thread along with the latest posts and have brought my detectors out of storage this week including the Vallon; looking forward to some tinkering.

[yaffle]

Hi there, Yaffle here from NL. Awesome thread that keeps on giving! Thanks for that y'all!
I have a VMH3CS incoming, as well as a Guartel MD8+. Will be interesting to see how they compare over here...
But, I read up on all the info on the headphones, and was wondering if anyone tried (building) this one?

http://makearadio.com/misc-stuff/piezophones.php

If so, is it a good fit for the Vallon?

Thanks,
Cheers,
Yaffle

[UK Detectorist]

See my PM.

Eric.

Hello, sent email Eric, cheers

[Ferric Toes]

Hello, thankyou to reply, ok I shall check those converters out, and look for some good batteries, I read Alkaline are best but you use Nicads ???cheers

See my PM.

Eric.

[UK Detectorist]

Hello, thankyou to reply, ok I shall check those converters out, and look for some good batteries, I read Alkaline are best but you use Nicads ???cheers

[6666]

You can buy a variety of "D" cell converters that use AA battery's
the ones I like come with 3 battery slots but you can plug 1-2 or 3 AA's into the side
I use just 2 AA nicad battery's in each converter .