Solve The Problem: Sticky Maglock

Have you checked the relays inside the maglock to verify that they both release cleanly? These relays have been know to stick and the replacement cost for the relay boards is minimal.

Is there only a single MOV/Diode? It sounds like the collapsing magnetic field of one coil may be inducing a burst of current into the other coil.

We sometimes "dimple" the lock. Using a linemans pliers hit the mag lock sharply with the edge of the pliers to raise a tiny dimple in several places on the magnet. Overall it lessens the holding force of the lock but depending on the lock and it's application this works.

Troubleshooting the sticky side of the maglock.

1. As mentioned previously, check to see if there is a separate feed for each of the electromagnets. If so switch the feeds and observe if the stickiness follows the feed. If there are two feeds and the stickiness follows the change in feeds then check the lock power relays (Altronix or equal) to see if they are sticky.

2. If there is only only one feed, switch the internal maglock circuit boards to see if the stickiness follows the change.

3. If there is no change in step 2, change the order that the internal maglock circuit boards are feed (which is first in the parallel circuit).

4. If none of this makes a difference remove any MOV/diodes and check again.

5. Last, but not least, if none of this makes a difference switch (assuming the posulated good maglock is the same as the sticky one) and see if there is a change in behavior.

I would be suprised if at this point you have not isolated the problem with the lock, the lock relays or the lock power supply.

Incidentally, testing the lock does not require removing the plates from the door- a screwdriver or any ferro-magnetic object will fall to the floor just as surely when the field collapses.

Thanks for the responses everyone.

In most situations, maglock 'stickiness' is attributable to power. In the situation described above, the 'MOV (metal oxide varistor)' or diode is a good place to start.

First, it is important to verify whether or not the lock actually needs an external MOV/diode. Many installers simply get into the habit of including them and add them without thinking if they potentially can cause issues.

Many new types of maglocks include internal MOVs and do not need a separate unit installed. See this RCI installation clip with the emphasis underlined:

Also note the importance polarity can play in wiring maglock RTEs for best performance. In this RCI example, connecting the RTE interupt (pushbutton or PIR) on the wrong leg may cause the bond to collapse more slowly than expected.

Secondly, confirm the MOV/diode is connected properly. Catch this Securitron instruction below:

In this case, an external MOV is recommended, but installing it backwards changes the behavior of the component and can cause 'sticky' locks.

Ignoring the role of these small components is no answer either. MOVs/Diodes are commonly specified or included with electronic locks to prevent long term damage to supply sources when the lock's electromagnetic field collapses. The field collapse causes an effect similar to 'backfeeding' into the power conductors. Over many thousands of cycles, this can damage power supplies or connected controllers.

In any case, residual magnetism is related to the presence of electricity (ie: capacitance) in the lock circuit. Degaussing the armature or 'dimpling the lock' are unnecessary and likely would have unintended negative consequences!

Props to Tyler Graham, Timothy Mc Pheron, and Bryan Kirkland.

Stay tuned for the next access problem: "Why did my proximity cards stop working?"

$1800 Maglock??? Is it gold plated?

Reminds me of an anekdote I once had.

I recieved a support call from a customer saying that their door wouldn't open.
I went over there and they had a maglock holding the door shut. I tried to get it to open, and indeed, it wouldnt budge. So I started to measure and noticed that the maglock wasn't getting powered. Which was weird, cause the door was still shut. I was starting to question the law of physics and started to unscrew the wires in case my meter was broken.

Yet to no avail. The damn door wouldn't open.

So I did what every technician would do. Use brute force. I slammed my large screwdriver between the maglock and the plate and excerting force. Finally I got the damn thing lose. And to my suprise, the plate was fully covered in sticky residue.

So what happened ? Well, apparently, the local lads thought the door falling shut would make quite a noise. So they stuck a few strips of isolation tape on the plate on the door. They then quickly found out that the door wouldn't lock, cause yeah, the plate isn't connecting anymore with the maglock. So they tried to remove the tape. But as we all prolly know, isolation tape doesn't remove so easy. So they only pulled off the foam, but the sticky stuff was still there.
THis then 'glued' the door shut.

After some chemicals I managed to get the damn stuff off. But it really made me question my sanity for a second there that a powerless maglock could still keep a door closed.