# Metal Detectors



## MDShunk

Sorry, I only have experience with Mettler-Toledo and OCS, and find them both decent brands. Never actually heard of the brands you're dealing with. In general, if balance voltage is maxed out, you might see if there's a phase angle setting you can fuss with next.


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## Jay Freeman

Thanks for the reply. I'll see what I can figure out.


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## BrettC

Jay Freeman said:


> I'm just curious if anyone here is familiar with how to re-balance these units.


Were you able to come up with any techniques to return them to normal operation? We have a variety of metal detectors at my new job and it's been quite the experience learning all the quirks of the system. There's one I've been on twice this week where the solution seems to be to up the sensitivity and then return it to the same setting and it suddenly works fine again.


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## Jay Freeman

The 2 units that I'm having the false trigger and balance issues with, are the Lock systems.

The company was taken over by Loma who offers very little technical assistance and nothing at all regarding re-balancing. For re-balancing, we'll need to call in a service technician but for now, I was able to eliminate the false triggers by experimenting with the phase angle. 

The one unit remains stable after setting the angle to 160 but the other unit has to be re-tweaked after they do a wash down. I found no signs of bad connections or water getting in anywhere. Changing the phase angle between 0 and 30 seems to get rid of the false triggers until they return and the phase angle needs to be set again. Before tweaking, the unit is very sensitive to vibration and when triggered, goes into a feedback loop and constantly kicks even with the air pressure turned off. Going from zero to 30 for example, gets it stable again but the problem returns later and setting back to zero gets it stable again.


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## BrettC

Jay Freeman said:


> The 2 units that I'm having the false trigger and balance issrues with, are the Lock systems.
> 
> The company was taken over by Loma who offers very little technical assistance and nothing at all regarding re-balancing. For re-balancing, we'll need to call in a service technician but for now, I was able to eliminate the false triggers by experimenting with the phase angle.
> 
> The one unit remains stable after setting the angle to 160 but the other unit has to be re-tweaked after they do a wash down. I found no signs of bad connections or water getting in anywhere. Changing the phase angle between 0 and 30 seems to get rid of the false triggers until they return and the phase angle needs to be set again. Before tweaking, the unit is very sensitive to vibration and when triggered, goes into a feedback loop and constantly kicks even with the air pressure turned off. Going from zero to 30 for example, gets it stable again but the problem returns later and setting back to zero gets it stable again.


We had an issue on a Fortress unit where water had collected underneath the conveyor inside the aperture. Since our product is very dry, it gave a lot of false readings. 

I don't play with the phase angle much; some here swear by it and others say don't touch no matter what. Sounds like they're temperamental no matter who makes them though!


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## BrettC

Jay Freeman said:


> The 2 units that I'm having the false trigger and balance issues with, are the Lock systems.
> 
> The company was taken over by Loma who offers very little technical assistance and nothing at all regarding re-balancing. For re-balancing, we'll need to call in a service technician but for now, I was able to eliminate the false triggers by experimenting with the phase angle.
> 
> The one unit remains stable after setting the angle to 160 but the other unit has to be re-tweaked after they do a wash down. I found no signs of bad connections or water getting in anywhere. Changing the phase angle between 0 and 30 seems to get rid of the false triggers until they return and the phase angle needs to be set again.  Before tweaking, the unit is very sensitive to vibration and when triggered, goes into a feedback loop and constantly kicks even with the air pressure turned off. Going from zero to 30 for example, gets it stable again but the problem returns later and setting back to zero gets it stable again.


We had the Mettler Toledo guy out today and yesterday to upgrade the guts on two of our Safeline machines. We were still having false rejections while testing the unit we've been having the most trouble with, and he found a loose bolt holding the protective cover on the head - which caused vibration issues - and he discovered that the shielding on the cable was no longer bonded to the equipment - causing ground loop fault issues. This cable incidentally is grounded at both the control panel housing and at the remote unit head, something I asked about since I had always heard you should only ground one side of signal cable. He said that was his understanding too but that this was the spec for this equipment. 

Had a good time talking with the guy; he was a navy electrical tech for 20 years before doing what he does now. I always like picking the brains of guys with different backgrounds than mine.


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