Access control problem with magnets

[grumblechops]

Hi, I have a problem with a few doors with magnetic locks. When you press the exit button you have to bump the door to get it open. This also happens with the fob when entering the building.

I've checked the lock output on the control card and it drops to 0v, so no residual voltage. I've even disconnected the magnet and the strike plate is still held.

It's a GDX5 system so I called them and they said the only thing to do is put some tape on the magnet.

Any ideas? The only thing I can come up with is the strike plate is becoming magnetised, but I don't know how to solve this.

The doors have two magnets. A 1200 and a 600. It is only happening with the 1200.

Many thanks for any help.

 

[alumni]

Check the 'kiss it's bearing is working correctly. This should protrude from the armature plate slightly. When the power is dropped this pushes the door slightly to break the bond.

 

[grumblechops]

Hi, thanks for the quick reply.
It's a Soyal AR 1200M magnet so that action is performed, I believe, by the rubber top of the strike plate bolt which compresses when the magnet and the plate engage. The bolt is fitted with the rubber protruding slightly.
I've been doing these magnets for 5 years now and have never come across this. I even tried renewing the magnet and plate to no avail.

By the way, the tape worked, but it's not exactly the most professional looking job.

 

[alumni]

Rubber doesn't do the same job. It isn't strong enough.
More a long short but do the locks have NOVa fitted?
Absence of these can cause problems.

 

[grumblechops]

I know what you mean with the rubber. The 600s have kiss it bearings and they're not causing any problems.

The control panels have MOVs fitted at the lock outputs. I tried adding diodes at the magnets but it didn't make any difference.

I might try and source a different make of magnet that has kiss it bearings instead of the rubber and see if that works.

 

[alumni]

I know what you mean with the rubber. The 600s have kiss it bearings and they're not causing any problems.

The control panels have MOVs fitted at the lock outputs. I tried adding diodes at the magnets but it didn't make any difference.

I might try and source a different make of magnet that has kiss it bearings instead of the rubber and see if that works.

The MOVs should be at the locks, not the controller.

As for diodes, i'd avoid. Whilst the kill the back emf they often cause lag - as in delay the door release.

 

[pred]

I dont profess to know what i'm talking about (ON THIS SUBJECT) but being a bricky i would hit it with a hammer.

Serious! if the striker plate is becoming magnetised correct me if i'm wrong, Hah!! they're queing up already, by srtiking the striker plate with a hammer it will demagnetise it, albeit temporarilly, but if it does work ok for a short while then you know you're on the right track, if it still sticks hit it with a bigger hammer.

 

[conny]

Or put it in an oven for a while.
Heat also de-magnetises.

 

[pred]

I get an imense amount of satisfaction hitting seven shades of 5hit out of an object.

 

[libby lou lou]

Or put it in an oven for a while.
Heat also de-magnetises.

Was going to fetch heat up but wasn't sure of the temp, we used to burn it on open fires when we was kids

 

[conny]

Hot enough that you couldn't handle it will probably be enough to alter the molecular structure but obviously the hotter the better.

 

[alumni]

Tends to bugger the door up though.

 

[grumblechops]

The MOVs should be at the locks, not the controller.

As for diodes, i'd avoid. Whilst the kill the back emf they often cause lag - as in delay the door release.

Cheers, I'll try moving the MOVs to the magnet