Woody Apparently Confirms That The 6000 Has No Active Shield

[jasong]

I don't think there are any coils that could get the 6000 close to the Z in depth performance. Two different technologies.

It's more likely they aren't building larger coils for the 6000 because there is little to be gained from using them. If there were serious gains to be had in terms of depth, I'm guessing X Coils would be doing it with an adapter already.

The 17x13 is underwhelming, and evidence of this lack of performance with larger coils. 

What Woody found is exactly what I was saying too for some time - it's not just the unshielded components, the control box itself lacks shielding and is a source of a lot of noise. I tried wrapping it with carbon fiber but it didn't help a lot, I didn't exactly cover everything though. I'm curious what Woody can achieve. We knew early on the fix was replacing unshielded inductors - these allowed the speaker to couple with the control board and self induce noise. But those components and maybe others as well were also susceptible to high EMI environments as well, so it wasn't just a purely speaker-related thing (this was the easiest to observe though). Both the speaker as well as high EMI environments would force the 6000 into instability. 

[Gold Catcher]

Unless there are technical issues to be resolved, they should just open the coil floodgates and let the customer deceid what coil would work best for them. Total compatibility. And If certain coils won't meet their high standard spec. requirenment for optimal detector perfomance, so be it. Worse comes to worse and the dector would then just not operate a peak performance, but the customer would still be in full control. If anything, this is what the huge interest in the Algo should teach them.

GC

PS: would love to see a big round spiral for the 6 (I think the 17 ML is semi spiral if I am not mistaken). As long as it can handle the ground. And with the Woody fix even better ?

[phrunt]

10 minutes ago, jasong said:

It's more likely they aren't building larger coils for the 6000 because there is little to be gained from using them. If there were serious gains to be had in terms of depth, I'm guessing X Coils would be doing it with an adapter already.

While I think they are very limited in the sizes they can release due to imposed restrictions, the above is deserving of a nod.

[Aureous]

No arguments that the 6000 is 'fairly good' with EMI handling, how it achieves this without a connected shield seems quite a mystery. Just Imagine it being as good as the E1500 with a proper shield? Ever since I bought a 6000, I was experimenting with an add-on copper foil shield and asked if the ML tech could one day add an active shield wire from the active internal graphite paint shield and poke it through somewhere so I could connect it. His dithering on the subject is now explained....there aint none! So I have only added an exterior passive shield onto another (interior)passive shield! A difference is noticed, but not hugely... Will be interesting to see how Woody's 6000's perform AFTER an active shield is added.....

[Aureous]

Woody has added another shorter video update on his progress....

 

[phrunt]

He's going to all that trouble and voiding any warranty anyway, why doesn't he just find a ground on the PCB and attach a small wire from it to the shield paint on the housing and paint the wire on with the shielding paint to bond it to the existing shielding paint, just make the wire long enough so he can pop the hood if he ever needs to..

Sheild wire is attached to the housing, Teknetics just stick it down with masking tape, I painted it on with the conductive paint then put the tape down again once the paint dried for a bit of peace of mind, then stupidly I decided to glue it down, well that wasn't the stupid part, the stupid part was leaving the tape: on before doing the glue so I had to use a bigger blob of glue ?

This was my paint

 

[Chet]

A graphite cabinet or housing shield does not have to be grounded to act as an effective shield. Any electrical EMI energy will be absorbed and dissipated as miniscule heat. 

Early television sets emitted a lot of EMI. To meet government requirements wooden and plastic cabinets were either internally painted with conductive paint or lined with thin screening or thin tinfoil. Some shields were grounded to the chassis some were not.

It appears that on the GPX 6000 they may have or maybe not intended to ground the graphite shield. The real test would be to compare one without the ground connection before and after the repair.
 

[phrunt]

2 hours ago, Chet said:

A graphite cabinet or housing shield does not have to be grounded to act as an effective shield. Any electrical EMI energy will be absorbed and dissipated as miniscule heat. 

That's why I'm not overly concerned, although having it connected would never hurt, as they say better to be safe than sorry, especially on a stupidly high-priced piece of equipment.  

It certainly made a difference on my poorly shielded 4500.  If you had a choice, it may or may not improve performance, but it can't hurt and could very well be beneficial, which would you choose? 

 

[Chet]

The shielding may be required to reduce EMI emission for government compliance requirements. That is to reduce EMI into nearby devices such as a cell phone.