Vallon VMH3CS Mine Detector

[brinbrin]

OK, I carved a o-ring into a worn tennis ball, the rubber of which happens to be the very same colour as the Vallon. No wobble any more, and way, way less noises. Thank you Mr Foster. You reign !
Still some noises though. When I replaced the armcuff, I saw the cord to the coil was covered in dust (Afghanistan ? Iraq ?). I'd clean the inside of the tube down to the soldering points of the plug, but with what ? I think pouring alcohol fuel and shake the tube...

[Ferric Toes]

Thanks for your replies.

The three screws were lose (?) but yes, I guess I will not go further - This parts are not to be disassembled. I'll put the screws back on with a drop of silicon.

The O-ring between the telescopic shaft and the body is cracked, still in one part, but cracked. Can I replace it by another ring ? I guess any O-ring could do, right ?

And The housing of the female part of the plug definitely lacks its O-ring since I bought it :-(. Here again, plumbing O-ring would do or should I buy the genuine part from Vallon ?

Best regards,

MC

I think you are mistaken about the cracked O ring. This is a clamping ring and is meant to have a gap in it. Tapers in the back of the larger outer shell and the body threaded part causes the ring with the gap to close on the shaft and lock it in place. Internal wear due to dust and constant use cause the taper on the knurled part to wear sufficiently so that it will not clamp tight.
PM me your address and I will send you the correct O ring for the plug.

Eric.

[Ferric Toes]

OK, I carved a o-ring into a worn tennis ball, the rubber of which happens to be the very same colour as the Vallon. No wobble any more, and way, way less noises. Thank you Mr Foster. You reign !
Still some noises though. When I replaced the armcuff, I saw the cord to the coil was covered in dust (Afghanistan ? Iraq ?). I'd clean the inside of the tube down to the soldering points of the plug, but with what ? I think pouring alcohol fuel and shake the tube...

The back of the connector with the female pins is sealed (cable too). In fact the top and bottom tubes are allowed to flood when searching in water. The drain holes however are usually blocked with dust. One in the shaft swivel at the coil end and the other at the base on the rear block under the knurled battery cap. The dust does not do any harm in these tubes but could be washed out if you wish. Water with a drop of washing up liquid would be enough if you have got the rear block off. The coil shaft is more difficult and I wouldn't bother.

Eric.

[brinbrin]

Wow, you used the word "oven-engineered" and I understand why. So, no chance there is a faulty soldering there. I guess the pins must have worn out, and beside replacing the upper shaft and the lower shaft/coil, there is no practical solution. Well, I'll make do with what I have. Eventually, I'll mod the whole unit to make it lighter. Thanks a lot for your answers.

[Ferric Toes]

Wow, you used the word "oven-engineered" and I understand why. So, no chance there is a faulty soldering there. I guess the pins must have worn out, and beside replacing the upper shaft and the lower shaft/coil, there is no practical solution. Well, I'll make do with what I have. Eventually, I'll mod the whole unit to make it lighter. Thanks a lot for your answers.

No, it wasn't heated in an oven. 'Over-engineered' means that the construction is stronger, sealings better, and fixings more secure, so as to ensure reliability in war zone conditions and manhanding by soldiers. The engineering level that would be classed as good for hobby use would not have survived very long in Afghanistan or Iraq.

Eric.

[brinbrin]

Sorry, it only was a typo. No way to "oven-engineer" anything, or maybe glass, ceramics, metal alloys, resins, etc, but certainly not a metal detector.

[Ferric Toes]

Sorry, it only was a typo. No way to "oven-engineer" anything, or maybe glass, ceramics, metal alloys, resins, etc, but certainly not a metal detector.

O.K. I did wonder if it was a typo, but had to laugh at the thought of oven-engineering. The sort of mistake a Chinese translator would make. I once saw an advert for a stereo phono cartridge where 'channel separation' was translated as 'chemical isolation'.

Eric.

[Myntmaster]

The manufacturing process of the coil is 38 cm. = 15 inches for Vallon.
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[tifred]

Thank you Myntmaster

[Myntmaster]

A couple more photos.
The longest in all of this is the drying process.
You can’t rush absolutely.
The graphite layer dries for at least 2 days. Epoxy up to 5 days.
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[Myntmaster]

Three coils are completely ready and are waiting for the opening of the hunting season.
The average coil 27x21 cm is more sensitive than the original 30.5x17 cm.
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[6666]

What graphite product are you useing ?

[Myntmaster]

I take from England.https://www.inoxia.co.uk/products/ch...raphite-powder
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[6666]

I take from England.https://www.inoxia.co.uk/products/ch...raphite-powder
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[ATTACH]49231[/ATTACH]
[ATTACH]49232[/ATTACH]
[ATTACH]49233[/ATTACH]

Thank you, what are you mixing it with and what ratio, what resistance do you get ? thanks

[Myntmaster]

Thank you, what are you mixing it with and what ratio, what resistance do you get ? thanks

Hi.
I make a graphite coating based on PVA glue B3 or B4.
After drying, the layer is completely water repellent. There are no special proportions. I take 100 ml. glue in a separate jar with a lid.
I sprinkle three teaspoons of graphite. Add one spoon, stir every time. Mixing thoroughly, I make control smears on paper.
It is necessary to measure after complete drying. If the resistance is in the range of 400-600 Ohms per 1 cm, then this is normal.
If the resistance is large, I add more graphite. If the mixture is thick or then slightly thickened, it can be diluted with acetone or solvent 646.
Store the finished mixture in a tightly closed jar. Stir well before each use.