PN# 500-18300
Page 9
Rev. D, 08/11
APPENDIX A: TROUBLESHOOTING
PROBLEM-- Unit will not operate when trigger wire is connected to +V.
On a new installation, make sure that DC power (12 or 24 volts depending on the model) is
connected to the red and black wires with correct polarity. When this is confirmed note that the
UnLatch will never operate unless the springlatch plunger is pushed in by the springlatch (see
Section 3.3). You can be “fooled” by this feature if you’re trying to test operate the UnLatch
with the door open. To do this, use a pencil or other similar object to lightly push in the
springlatch plunger and then close the trigger wire to +V and you will see the UnLatch plungers
move.
On a service call for a unit with successful operating history, in addition to the checks mentioned
above, check to see if the door and latch have gotten into a warped situation where there is
heavy pre-loading on the door. The UnLatch’s motor may not be able to release the latch under
this condition but you should be able to hear it trying to release the latch. The UnLatch will
automatically shut down its motor if it can’t release the latch within 1.5 seconds. It will operate
normally when it is re-triggered. You should be able to try operation by removing the pre-
loading by pushing the door closed with enough force to counteract the pre-loading. Note that
this situation is more likely if power supply capacity is less than 3 Amps (see Section 3.1).
Corrections for this type of warped door situation is to have the door serviced and possibly
increase the capacity of the power supply.
If the unit still will not function, note that it does have an internal microprocessor that may have
gone into a crash condition which may leave the unit’s gears and plungers in an unusual
position. This can happen sometimes if the unit is under-powered (see Section 3.1) and has
consequently stalled (the motor is not receiving enough power to operate the latch). While the
motor is in the process of stalling, voltage to the processor will sharply drop and this can crash
the microprocessor. A crash can also occur as a random event but this is unusual. There are
two recovery methods that may be used to recover the unit’s operation. The first technique is a
simple reset achieved by cycling power to the unit. Remove power (+V) from the unit’s red wire
momentarily. After power is reapplied, the unit may reset and begin normal operation. If this
recovery method did not work perform the second recovery method (POWER ON RESET).
Remove power (+V) from the unit’s red wire. Connect the unit’s red and orange wires together.
Now reapply power (+V) to both the orange and red wires simultaneously. This re-initializes the
firmware and may cycle the unit to the unlocked position. Once this operation has been
performed, return the unit to standard wiring (orange only connects to +V to trigger the unit.)
Finally, the unit could have experienced motor failure or other internal electronic failure. It is
repairable by the factory.
PROBLEM -- Unit will occasionally not operate.
Generally, this comes from too much door pre-loading possibly coupled with a low capacity
power source. When the UnLatch can’t generate enough torque to release the latch, it
automatically shuts down but then operates the next time it is triggered. See the previous
paragraph.
PROBLEM -- Latch does not re-secure when the door re-closes.
This is not a problem with the UnLatch but is rather a problem with the installation. The latch is
simply not moving into position. Make sure the door closer is properly operating to re-close the
door with reasonable force. Next, re-read Section 2.5 to make sure the UnLatch is in the correct
position with respect to the door stop.
PROBLEM -- Latch status sensing does not function.
The latch status output contacts (see Section 3.3) will change state when the springlatch plunger
is pushed in. To check this, therefore, push the springlatch plunger lightly in with a pencil or
other similar object. Make sure the unit is receiving power when you make this check or the
output contacts will not switch. If they still do not switch, the unit will need to be returned to
the factory for repair.
PATENTS
The UnLatch is covered under U.S. patents #5,474,342 and #6,022,056 with other US and
international patents pending.
