Assa Door Lock User Manual

PN# 500-18800 Page 1
Rev. A.1, 8/01

SECURITRON MODEL MUNL-12, MUNL-24 MORTISE UNLATCH

INSTALLATION AND OPERATING INSTRUCTIONS

1. DESCRIPTION

Securitron’s Mortise UnLatch is a revolutionary new type of electric strike which eliminates the
necessity to perform a routing operation on the door frame for installation. The motor
driven Mortise UnLatch also presents a fully concealed appearance on the door which not

only enhances architectural appeal but improves security over a conventional electric strike as
an intruder is less able to determine the type of security device present on the door. The
Mortise UnLatch functions with all North American mortise locks and includes a latch

status output which reports when the door is in latched (secure) condition or is open.
Product Specifications are: Input Voltages: 12 VDC (MUNL-12), +20%, -10%. 24 VDC

(MUNL-24), +20%, -10%. Current: At rest: 40 mA (either voltage). When operating- 4 Amp
input surge @ 12 VDC; 2 Amp input surge @24 VDC for 100 milliseconds and 600 mA @ 12
VDC or 300 mA @ 24 VDC during motor movement. Operating Temperature: -10° to 125° F.

FIG 1: MORTISE UNLATCH DIMENSIONS (INCHES)

1.25

1.88

3.50

4.88

2. PHYSICAL INSTALLATION

2.1 SURVEY

1.25

3.38

SPRINGLATCH
PLUNGER

DEADLATCH
FINGERS

RECOMMENDED TOOLS

MEDIUM + SMALL PHILLIPS DRIVER
MEDIUM SLOTTED DRIVER
CHISEL, 5/64 ALLEN WRENCH
WIRE CUTTER/STRIPPER
VOLT/OHM MET ER
CRIMP CONNECTORS
CRIMP PLIERS

The installer must first be sure that the latch is of the mortise type
(see the drawing to the right.) A mortise lock (or latch) includes a
square shaped springlatch and a “pin” called the deadlatch pin or
guard bolt which may be positioned either above or below the
springlatch. Most mortise panic bar latches are also perfectly
compatible with the MUNL. Note, however, that if the mortise lock
assembly includes a dead bolt, the dead bolt will not be operable
The most common alternate type of latch in use in North America is
called cylindrical, tubular or bored. The standard UnLatch (model
numbers UNL-12 and UNL-24) is designed for this alternate type of
latch. Securitron does not offer an UnLatch solution for a rim latch
(rim latches are on the surface of the door rather than being mortised

Springlatch

into the middle of the door). Deadlatch Pin

 Copyright, 2001, all rights reserved • Securitron Magnalock Corp., 550 Vista Blvd., Sparks NV 89434, USA

Tel: [phone] • (800) MAGLOCK • Fax: [phone] • Website: www.securitron.com

An ASSA ABLOY Group company

Rev. A.1, 8/01 Page- 2

2.2 HOLLOW METAL (STEEL) FRAME MOUNTING

Remove the existing ANSI 4 7/8” strike plate (it will be discarded) and experimentally try to fit
the Mortise UnLatch in the resulting cavity. In some cases the cavity will be large enough to
accommodate the Mortise UnLatch and you will have nothing to do but pull the wires up the
hollow door frame and screw the Mortise UnLatch into place. In other cases you will find a
“dust box” within the frame that will get in the way of the Mortise UnLatch. The dust box must
be cleared away to make room. Generally, a sabre saw, dremel tool or a drill with a fly cutting
bit is the most effective tool to do this. You can also find that the edge of the dry wall panel
interferes with the Mortise UnLatch. Simply chip away some of the dry wall with a screwdriver.
Once you are able to fit the Mortise UnLatch into the frame, vacuum out any concrete dust
and metal shavings (these can work their way into the UnLatch mechanism and cause
problems) and loosely mount it and proceed to Section 2.4, adjusting for latch/deadlatch
location. Note that the face of the Mortise UnLatch is protected by a removable film.
Leave this on during the “pre-mounting” so as to preserve the metal finish against scratching
and to block the possible entry into the mechanism of dust or metal shavings. Remove the film
when you adjust the unit for latch/deadlatch location (Section 2.4).

2.3 WOOD FRAME MOUNTING

For installation in a wood frame use a chisel to create a space for the Mortise UnLatch behind
the existing strike. Remove the strike and place the template (last page of this manual) on the
door (registering it to the strike mounting holes). This will show you the space that must be
chiseled out. As you get close to finishing the chiseling job, experimentally try to fit the body of
the Mortise UnLatch in the cavity. This will avoid chiseling too big a space. A tight fit is
preferred as it helps the solidity of the mounting. Normally, with a wood frame, the wires will be
run inside the wall. Simply drill from the back of the cavity you have created rearward into the
wall space to admit the wires. To mount the Mortise UnLatch to the wood frame, use the two
#12 x 1” furnished flat head wood screws. Once you are able to fit the Mortise UnLatch into the
frame, vacuum out any wood dust and metal shavings (these can work their way into the
UnLatch mechanism and cause problems) and loosely mount it and proceed to Section 2.4,
adjusting for latch/deadlatch location. Note that the face of the Mortise UnLatch is protected
by a removable film. Leave this on during the “pre-mounting” so as to preserve the metal
finish against scratching and to block the possible entry into the mechanism of dust or metal
shavings. Remove the film when you adjust the unit for latch/deadlatch location (Section 2.4).

2.4 ADJUSTING FOR LATCH/DEADLATCH LOCATION
One of the remarkable features of the Mortise UnLatch is that it adjusts to suit different

models of North American mortise locks. With conventional electric strikes, the strike model

typically needs to be matched to the lock/latch model and this complicates sourcing the electric
strike. There is one known exception: Sargent model 7800 or 8200 in retrofit (the lock is
already present). The Sargent lock can not normally be accommodated because its springlatch
and deadlatch pin are positioned so close to the bottom of the opening. To employ the Mortise
UnLatch with Sargent, purchase the accessory tab kit, model #STK-1. These new mounting
tabs sufficiently reposition the Mortise UnLatch to make it work with the Sargent Lock. Note that
in new construction, when the door and frame have been specifically prepared for the Mortise
UnLatch and Sargent 7800/8200, the accessory tab kit is not needed.

Adjustment of the Mortise UnLatch is necessary because different lock manufacturers vertically
position both the springlatch and deadlatch pin in widely differing locations along the lock body.
The Mortise UnLatch accommodates this by allowing positional adjustment of its springlatch
plunger (the component which pushes in the springlatch) and then operating the deadlatch pin
though moving “deadlatch fingers” which fill the rest of the strike opening.

The adjustment procedure is accomplished in two logical steps. First you must determine the

position of the springlatch plunger and then perform the adjustment to set that position.

2.4.1 DETERMINING SPRINGLATCH PLUNGER LOCATION
The goal of this determination is to vertically align the Mortise UnLatch’s springlatch

plunger with the lock’s springlatch. The deadlatch pin will then be “automatically” operated

by the deadlatch fingers regardless of its position on the lock. It’s important, however, to
determine the position in such a way that maximum tolerance is achieved in the event that the
door shifts against the frame.

To begin, loosely mount the Mortise Unlatch and close the door so that you can see the top and
bottom of the lock’s springlatch. Draw lines on the lip of the Mortise UnLatch’s strike which
correspond to the lock’s springlatch position. Next dismount the Mortise UnLatch. The drawn

Rev. A.1, 8/01 Page- 3

lines and knowledge of the gap between the springlatch and deadlatch pin are used to
determine the vertical position of the springlatch plunger. When this gap is greater than ¼”,
best reliability is obtained when the springlatch plunger position is centered on the springlatch.
When the gap is smaller than ¼”, however, simply centering the springlatch plunger risks
positioning the deadlatch pin too close to the springlatch plunger so the procedure is to position
the edge of the springlatch plunger midway between the springlatch and deadlatch pin. Figure 2
illustrates these points.

FIG. 2: DETERMINING POSITION OF SPRINGLATCH PLUNGER

GREATER THAN 1/4" GAP

SPRINGLATCH

MEASURE GAP
BETWEEN
SPRINGLATCH AND
DEADLATCH PIN

DEADLATCH PIN
(MAY BE ABOVE)

GAP BETWEEN
DOOR AND FRAME

SPRINGLATCH
PLUNGER

DRAW LINES ON MORTISE
UNLATCH DENOTING TOP
AND BOTTOM OF SPRINGLATCH

CURVED LIP OF
MORTISE UNLATCH

LESS THAN 1/4" GAP

WHEN THE GAP BETW EEN THE SPRING L AT CH AND DEA D LATCH PI N
IS LESS THA N 1/ 4 ", SET THE BOTTOM EDGE OF THE SPRINGL ATCH
PLUNGER MID WA Y BET WE EN THE SPR I NG L ATCH AND DEAD LAT C H
PIN. (NOTE THAT THE DEADLATCH PIN MAY BE BELOW THE
SPRINGLAT CH AS IN THIS EXA MPLE, OR ABOVE IT)

SPRINGLAT CH BOTTO M EDG E (EXAMPLE)
DEADLATCH PIN TOP EDGE (EXAMPLE)

EXAMPLE OF SPRINGLATCH
PLUNGER CENT ER ED WI T H
RESPECT TO SPRINGLATCH
POSITION (SHOWN BY
DRAWN LINES). THE PLUNGER
SHOULD BE CENTERED WHEN
THE GAP BETWEEN THE
SPRINGLATCH AND DEADLATCH
PIN IS GREATER THAN 1/4"

MIDWAY POSITI ON

2.4.2 ADJUSTING SPRINGLATCH POSITION

Now that you have marked the unit with the correct position for the springlatch plunger, the
actual adjustment must be performed. Figure 3 shows the procedure.

Rev. A.1, 8/01 Page- 4

FIG. 3: ADJUSTING SPRINGLATCH POSITION

Perform these adjustments
with the unit on a flat surface
and be careful not to lose
the small screws

Remove Small Cover

A-

(Small Phillips Driver)

SMALL COVER (A)

Remove "U" Shi el d

B-

(5/64" Allen Wrench)

Be especially careful not to let a screw or any other object fall
inside the housing as it can jam the Mortise UnLatch

C-

Push in Springlatch plunger
and hold it

"U" SHIELD

D-

Slide Fingers as necessary
(You must push them from
their base; you can use a
small screwdriver)

SMALL COVER SCREWS (B)

SHIELD SCREWS
(SOCKET HEAD CAP)

Deadlatch
Fingers

E-

Slide and center springlatch + shield
in the new opening. Then allow it
to spring out.

F-

Replace Shield and Small Cover

2.5 FINAL ADJUSTMENT WITH SPACERS

For reliable operation, the door needs to close so that the latch easily enters and is retained by
the Mortise UnLatch. The door should not have to be pushed to engage as can be the case
with a poorly fitting or poorly closing door. To check this point, when the Mortise UnLatch has
been mounted, after the door is closed and latched, you should be able to “rattle” the latch
against the Mortise UnLatch plunger by pushing the door in and out. The amount of

movement in the door latch should be about 1/16-1/8” (1.5-3MM).
If the amount of slack or rattling is greater than 1/16-1/8”, you need the door to “close

earlier”. In effect, the edge of the stop needs to be closer to the Mortise UnLatch. To adjust for

this, first check to see if the stop has “silencers” on it. These are cylindrical rubber bumpers
which quiet the noise of a closing door but also have the effect of making the door close earlier.
If you have silencers and the door is still rattling too much, contact the factory for additional door
stop spacers (the Mortise UnLatch is shipped with two). If you don’t have silencers, add one or
two door stop spacers as is shown in Figure 4 to cause the door to close earlier.