Vallon VMH3CS Mine Detector

[stefan-s]

Yes, both are modded an both does have the same problem.

I just tested the cable out of the enclosure first with the 6mm coax coil cable the problem was the same.
After the first test i changed the 6mm coax coil cable with the standard spiral vallon coax cable and made a connection from the outer shield of my connector to the battery - pin. After this change it seems a little less nervous i can set the sens on max 8/9 now but 12 is still not possible it will go crazy again. I tested in all channels and banks.

So maybe the problem is in the cable?

really frustrating.....

Hi Stefan,

Thanks for for sharing the photos. Am I correct in saying you have 2 Vallons and both are modded and both exhibiting the same problem?

Have you tested with the internal coil cable section out of the enclosure?
eg not running under the PCB and if so, did it still have the problem?
Did you remove the coax cable pins from the internal black socket or just cut the cable and fit the new 3 pin end?

The coax seems quite large, diameter I'm wondering if this is causing an issue?

[Ferric Toes]

It may be the connector which is causing the problem. Remove the connector and just solder the two coax's together. Splitting the coax through a metal bodied connector will generate eddy currents in the connector body. That is why I prefer plastic bodied connectors. If the connector is coaxial then that is OK as there is no external magnetic field to interact with the metal.

Eric.

[stefan-s]

Thanks eric,

I will try it tomorrow.

[Ferric Toes]

The Bridport Beast

This is the ultimate predator. I have added a Garrett Z link, a push button by the hand grip and perfect balance. The Z Link works great with no noticeable delay and good tone. The C button on the handle is for quick compensation and has all sorts of functions in combination with other switch and button settings.

Eric.

[Carolina]

Well sir, that didn't take long!!! Will show Clay. I like it!

Carolina

[Mdtoday]

Great work Eric, that's a nice looking bit of kit!

Brian

[stefan-s]

Looks good eric

[stefan-s]

Problem sloved do you have some tips for a good connector?

[Ferric Toes]

Problem sloved do you have some tips for a good connector?

Hi Stefan,
The problem is that you don't have much room. What I would do is put a coil connector in place of the 6 pin and route the audio for phones to the back end via the black tube. For standard phones you will need a step down transformer. The only thing you need from the 6 pin is the audio as the RS232 connections are for programming and I doubt you will be doing any of that.

It may be that part of the problem is the close proximity of the audio, which is probably a 10V pulse waveform, which is very close to a sensitive receiver loop where the coax splits in the connector. This could give you a feedback effect which makes the detector unstable.

I will think about it and get back to you.

Eric.

[chirosi]

Hi,
I'm new here but have been following this thread with interest as I have purchased two of these detectors now from different sellers on ebay. Unfortunately both seem to have the same fault which seems a little odd.
Both machines are dated 2010 and both have broken seals. When switching the units on they both start up correctly and run through the start up sequence fine but then refuse to settle and throw off random ghost signals when swinging the detector. I have tried changing the frequencies as detailed in this thread and also tried in normal and mineral mode with ground balancing and without. I have also tried testing it in different locations that should be a long way away from any EMI, none of which helps. Movement of the detectors seems to be causing the ghosting.
Has anyone any ideas please as to what the problem might be. Am I doing something wrong or have I just been very unlucky? as I find it strange that I have managed to get two different machines from different sources both exhibiting the same problem.

Thanks, Si

[Ferric Toes]

Hi,
I'm new here but have been following this thread with interest as I have purchased two of these detectors now from different sellers on ebay. Unfortunately both seem to have the same fault which seems a little odd.
Both machines are dated 2010 and both have broken seals. When switching the units on they both start up correctly and run through the start up sequence fine but then refuse to settle and throw off random ghost signals when swinging the detector. I have tried changing the frequencies as detailed in this thread and also tried in normal and mineral mode with ground balancing and without. I have also tried testing it in different locations that should be a long way away from any EMI, none of which helps. Movement of the detectors seems to be causing the ghosting.
Has anyone any ideas please as to what the problem might be. Am I doing something wrong or have I just been very unlucky? as I find it strange that I have managed to get two different machines from different sources both exhibiting the same problem.

Thanks, Si

Hi Si,

You don't appear to be doing anything wrong, but the fact that two machines have the same problem is very strange. Out of about 20 units that I have worked on, some of which were very bad cosmetically, only one had an electonics that has a fault. If it fires up and goes through the start sequence, then it is working correctly. Sometimes a key pad is stuck but that doesn't affect the default operation.

Some basic questions 1. Do you have only one machine switched on at a time? 2. Is you mobile phone switched off? 3. Have you swapped coils from one machine to the other? Do the contacts (male and female) on the 7 pin shaft connector appear undamaged? I always clean out any dust and apply a drop of contact cleaner/lubricant to them.

Eric.

[chirosi]

Hi Eric,

Thank you for taking the time to reply and thank you for all your hard work with this machine and all your help on the thread here.

The first machine has been returned and the second machine is going back on Monday. So.... 1. Yes, only one machine switched on at a time 2. Yes phone was switched off when testing outside. 3. unable to try that as first machine returned 4. The connectors appeared undamaged and I did clean them out.

I am totally baffled. Both machines were tried in many different locations where no EMI should of been present and both appeared to have the same problem. The problem seemed to appear mainly when swinging the detector as you would normally when detecting. It felt to me like it was making a bad connection when doing this, causing the machine to spike and give off false signals. Could the machines have a shielding issue that only shows up when moving the unit and be fine when stationary to run through the start up test sequence? Adjusting the sensitivity and using normal or mineral mode did not make it any better. All I know for sure was that both were totally unusable in that state, hence the returns.

I'm not sure what to do now as I really fancied one of these and have been reading up about them here for a while now. I may order another but my confidence with them now has worn thin

Thanks, Si

[Carolina]

Si: TDI Electronics, Poland have sold me two VALLONS and back packs at reasonable prices. I see one listed now with broken arm rest and they are asking for an offer. $100 US should buy it. Well, watch their adds and always make an low offer. My first purchase came with rabbit ear arm cuff but the add showed the newer two piece. I complained and got $100 US return. Good people.

Carolina

[Ferric Toes]

Hi Chirosi

See PM

Eric.

[chirosi]

Si: TDI Electronics, Poland have sold me two VALLONS and back packs at reasonable prices. I see one listed now with broken arm rest and they are asking for an offer. $100 US should buy it. Well, watch their adds and always make an low offer. My first purchase came with rabbit ear arm cuff but the add showed the newer two piece. I complained and got $100 US return. Good people.

Carolina

Thank you... I will check that seller out

Si