Pi Question - Coils Power On & Off

[DSMITH]

I keep reading in a few different post (To Not Turn A PI On Without a coil connected)

I have not attempted to do so because of reading what I quoted, but have often been curious as to what would happen if one was to turn a PI on without a coil connected

I know with a VLF generally you will get a coil Error pop up and for instance like the Legend the Legend will shut itself down with out a coil attached

so can someone explain to me what happens if you power up a PI with out a coil attached (Just Curious)

also why do manufactures not put in a fail safe to prevent a PI from powering up with out a coil connected, if it can cause harm to a PI again just curios because of a statement in one of @Steve Herschbach recent post

[Steve Herschbach]

Probably nothing, but on a high power PI you could also blow the front end circuit. Less a worry with the AA 12V units but you can bet an issue with SD/GP/GPX and GPZ high power detectors. Even them you’ll probably get away with it, but why run the risk?

From the GPX 5000 manual:

“Always ensure that the control box is turned off before connecting or disconnecting the coil to avoid damage to the detector's electronics”

[DSMITH]

11 minutes ago, Steve Herschbach said:

Probably nothing, but on a high power PI you can also blow the front end circuit. Less a worry with the AA 12V units but you can bet an issue with SD/GP/GPX and GPZ high power detector. Even them you’ll probably get away with it, but why run the risk?

From the GPX 5000 manual:

“Always ensure that the control box is turned off before connecting or disconnecting the coil to avoid damage to the detector's electronics”

Thanks for clearing this up Steve, even though I never turn any of my detectors on without the coil connected, I was just curious on a PI, because of statements I have read but no one ever explained the why, so again thank you for taking the time to answer what is probably a common since answer LOL

[phrunt]

I've accidently changed coils on my GPZ from a 12" Spiral to a 10" without turning it off, I did a hot swap at the adapter.  It wasn't intentional and I wouldn't do it again unless accidental, but no damage was caused, it just shut down with a coil error, fired back up fine afterwards.   It's better to be safe than sorry though and always power down. 

JW's 6000 was in use, and the coil started acting up just really unstable so he started the noise cancel procedure then it did a coil error so he shut down, powered back up and no longer was a coil detected so the chip in the coil likely fried I guess, either way it didn't' damage the detector and having the chip fried is similar to having the coil disconnected.

It's not something you want to do, but if it happens by accident, you would probably be fine.  They're probably more worried about you trying to plug the coil in and get it lined up wrong where a pin with power contacts one it shouldn't, that could be a big issue.

[Geotech]

Offhand, I can't think of a PI design that will be damaged by turning it on without a coil connected. In fact, it would be engineering malpractice to release such a design. In designing and building PI circuits, I hot-swap the coil all the time and don't think twice about it. That said, I suggest following the manufacturer's recommendation.

[rvpopeye]

 I have experience with systems that have a turn on/off sequence .(on and off usually being opposite)

(Tweeter drivers can get expensive ....don't ask me how I know that.) 

But individual units ? I don't recall any with such restrictions except don't hot patch a condenser mic !  Maybe similar transient issue in a PI coil w/chip ?

BUT  

After Geotech's response above , due to my inexperience under a detector's hood I would defer to him.... and the disclaimer. 👍 

[Dutchman4]

Two different scenarios are being described here:

1.  The original question was "what would happen if one was to turn a PI on without a coil connected?"  In this case I would also expect that nothing would or should happen because there is no load (coil) and there should be no current flow.

2.  What would happen when "hot swapping a coil" or better said swapping a coil when the detector is turned on.  In this case the load (coil) is being disconnected and/or connected with the detector on and hopefully the detector is designed to withstand this but I would consider this risky with any piece of electronic gear that has an external load connected with a cable or wire. 

[RONS DETECTORS MINELAB]

I remember in JP’s GP 3000 &.3500 video’s he would always disconnect the power cord prior to coil swapping, so must of been a problem at that time. With the GPX system we get a coil overload, not sure but maybe this coil overload feature was a solution to the older GP series issues. I always follow JP.s example on every detector because i do not want to take a chance of damaging the front end.

[Steve Herschbach]

I would never worry about powering up a control box without a coil attached. On the other extreme, I would never under any circumstances want to connect or disconnect a coil on a GPZ 7000 if it was powered up, but due to the way you have to half disassemble the detector to do this it is unlikely anyone would. On the other Minelabs Carl is probably right but it is also something I would never do. We are creatures of habit, and developing a habit of being sure a detector of any sort is not powered up when connecting or disconnecting a coil will never cause you grief. You can't say the same the other way around so do please just look at it as good practice. And again...

From the GPX 5000 and earlier manuals:

“Always ensure that the control box is turned off before connecting or disconnecting the coil to avoid damage to the detector's electronics”