Fortress metal detector

[stuartye55]

Hi

I have a Fortress Phantom metal detector which lost power on Wednesday. Upon investigation, I found the power supply (240vac in, 24vdc 1.7a and 5vdc 1a out)to be faulty. Due to not being able to get one of these immediately, I purchased an Omron 24vdc power supply and 5vdc power supply and fitted them. Once powered up I couldn't get the detector to stabilise. I've gone through the usual noise filters, phase angles and sensitivity inside the metal detector settings etc and managed to settle it down with the occasional fluctuation (detection) but this won't then detect the metal test pieces. I've installed a powr supply from another fortress unit and this has removed the issue but can't understand what the difference is. Has anybody any idea what would be causing this? Would a power supply filter remove some of the noise the detector is currently seeing? Any help gratefully appreciated.

Regards
Stuart

 

[IRstuff]

Are you sure the power supplies are equivalent?

"lost power on Wednesday"

But, what caused the "lost power?" Is it strictly the power supply? Or did something else cause the power supply to fail?

TTFN
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[stuartye55]

Hi

Component failure inside the power supply caused the supply fuse to blow.

 

[IRstuff]

My point is why did the components fail? Was it because of overload from the metal detector?

TTFN
faq731-376

Need help writing a question or understanding a reply? forum1529

Of course I can. I can do anything. I can do absolutely anything. I'm an expert!

 

[stuartye55]

Unit is over 15 years old, when testing there where no shorts etc that caused the supply to blow so just presumed it was component failure inside the power supply!

 

[VEBill]

Based on your description, maybe start by checking the grounds, commons, and returns around the power supply wiring. Make sure the stand-in power supplies are wired up the same as the original in this area. Common vice isolated grounds, returns, etc. It's low odds, but it's the next thing that I'd check if I were you.

Another possibility is the magnetic emissions from the new PSs are impacted the detector itself (magnetic fields). Perhaps the original PS has some tight specs in terms of not impacting the system.

 

[stuartye55]

Thanks VE1BLL

That's more what I was looking for - Interference from the new power supplies causing the metal detector to be erratic. Metal detectors are so fussy, having 2 detectors in close proximity, using frequency inverters or motors to close to them all trigger false alarms. So is there something in these new power supplies that is possibly being filtered in the original power supply and will a 'passive filter' do the same job? Someone suggested 'dirty noise' from the power supplies, presume this is humming?

 

[itsmoked]

The supplies you're using as replacements are likely switchers. Switchers by design often need to have ripple in their outputs as that is what their controllers use for feedback. This means your detector may be seeing this ripple and it's causing false trips.

If you can get some linear supplies after checking VE1BLL's suggestions they'd probably work for you.

Got a close-up picture of your old supply?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[VEBill]

One more possibility for the To Do list. Check the routing and dressing (installation details) of the PS wiring. Being a metal detector, perhaps such seemingly trivial details matter.

The 'Linear PS' is a very good suggestion too.

 

[Comcokid]

I think itsmoked has zero'ed in on the issue. Small modular power supplies are usually switchers, and have noise, ripple, and emit EMI. The new power supplies may have emissions at the same frequencies the metal detector uses, and the power supplies are swamping out the detectors.

 

[stuartye55]

Thanks for the replies guys. I'll let you know how I get on. Fingers crossed as I've noticed the linear power supplies are twice the cost!

 

[stuartye55]

Phoned everywhere trying to get hold of these linear power supplies - Only one I managed to get was the 5vdc. Swapped it over and powered up, reset all parameters to what they ran at before starting this and the signal very stable, unfortunately too stable, didn't even detect the metal test sticks. Think i'll have to wait for the original one to arrive!

 

[sbkenn]

SMPS noise v analog quiet ?