40-6791 & 40-6792 Machine Mount Detector and Remote Display

The Johnson machine mount laser detector (40-6791) pairs with your

Johnson red beam rotary to help you detect laser signals directly on

your equipment - perfect for one-person grading and excavation.

The detector can be used alone or paired with the 40-6792 remote

display that mounts in the operator’s cab and repeats the detector’s

signal in a more convenient position for the operator to view.

This laser detector features:

• 360° detecting window detects the

laser signal from any position

• Accuracy up to 1/8” (ﬁne mode)

• Accuracy up to 1/4” (coarse mode)

• Ultra-bright LED indicators

• Lithium ion battery and 12/24V cable

• Dust and rain resistant construction

40-6791 & 40-6792 Machine Mount Detector and Remote Display Manual

www.johnsonlevel.com/manuals

CHARGING THE BATTERY

1. If operating o 12/24V machine power, the battery will

automatically charge from your input source. Use the attached

connector cable to hook directly to the equipment battery.

2. If operating o of the Li-ion battery, recharge when the

detector fails to operate - the run time from a single charge is

approximately 40 hours.

3. To recharge the detector, supply 12/24V machine power or use

the included 120V adapter. Charge time is approximately 6 hours.

If using the 120V adapter, charging is complete when the LED on

the charger changes from red to green.

GETTING STARTED

1. Charge the battery, or connect the detector

equipment power. See “CHARGING THE BATTERY”.

2. If using the 40-6792 remote display, mount it and

install the connector cable from the remote display

to the detector. If using 12/24V power, hook the

MOUNTING THE DETECTOR

Position the detector as close to vertical as possible and so it moves

with your bucket/blade. It’s easier to mount the detector ﬁrst, then

adjust the laser to the desired grade position, since adjusting the

laser tripod is easier than relocating the detector on your equipment.

The detector includes both magnetic and clamp mounts. For

temporary installation, the magnets are recommended, while the

clamp mount is recommended for permanent installation.

To switch from the magnetic mount to the clamp mount:

1. Use the included 2mm hex wrench to loosen

the setscrew on the side of the mount. It is not

necessary to fully remove the setscrew.

2. Unthread the magnet assembly from the mounting

stud. It may be necessary to use a tool to complete

this, though it can generally be loosened by hand if

not previously over-tightened.

3. Install the clamp using the included washer

and nut. Use either a 5/8” or 16mm socket (not

included) to tighten the nut. To replace the

magnets, reverse these instructions.

POWER BUTTON

power cable to the remote display - it will power the detector.

3. Attach the detector to your equipment. See “MOUNTING THE

DETECTOR” for helpful hints on choosing a location.

4. Press the detector power button to turn on the detector.

5. The detector starts in coarse accuracy mode. Set the accuracy

mode to coarse or ﬁne by pressing the detector power button.

See “SETTING ACCURACY”.

6. Operate the detector. See “USING THE DETECTOR”.

7. When you are ﬁnished using the detector, power it o by

pressing the detector power button for three seconds. All LED’s

will brieﬂy ﬂash to indicate the detector is powering o.

www.johnsonlevel.com/manuals

1. This detector has two accuracy settings: coarse and ﬁne. The

detector will always start in coarse accuracy mode.

2. To toggle accuracy modes, press the power button while the

detector is powered on.

3. The arrows on the detector will ﬂash three times to indicate the

current accuracy mode, as follows:

SETTING ACCURACY

USING THE REMOTE DISPLAY

COARSE MODE

The exterior red

LED’s will ﬂash

three times.

FINE MODE

The interior red

LED’s will ﬂash

three times.

Coarse mode maximum accuracy: +/- 1/4”

Fine mode maximum accuracy: +/- 1/8”

Pro Tip: Use coarse mode for rougher work such as general

excavation to ﬁnd the beam more quickly. Use ﬁne mode for more

precise location of the beam, such as when preparing for a concrete

pour, preparing a driveway or roadway, or other precision tasks.

The remote display mounts inside your operator’s cab and repeats

the arrow pattern of the detector in a more convenient location for

the operator.

Similar to the laser detector, the remote display will ﬂash to indicate

grade as follows:

There are no controls on the remote display - it automatically

operates when the detector is powered on.

If operating the detector using its internal battery, the detector will

also provide power to the remote display.

When operating from 12/24V machine power, connect the power to

the display, and it will provide power to the detector.

Below Grade

(move up)

>2”

Below Grade

(move up)

<2”

On Grade

Above Grade

(move down)

<2”

Above Grade

(move down)

>2”

USING THE DETECTOR

1. This detector must be used in conjunction with a red-beam rotary

laser and must have direct line-of-sight to the laser in order to

receive a signal. This detector can read from 360°, so no speciﬁc

positioning is required provided that line-of-sight is established.

2. Pass the detector through the plane of laser light. The detector

will begin to ﬂash to indicate the grade position as follows:

Below Grade

(move up)

>2”

Below Grade

(move up)

<2”

On Grade

Above Grade

(move down)

<2”

3. For example, if the top arrow is ﬂashing, the detector (and your

equipment) must be raised to ﬁnd grade. The topmost and

bottommost arrows indicate that your equipment is greater than

2” from on grade.

4. The detector will remember its last position if the laser beam

signal is lost or interrupted. This helps you more quickly locate

grade when the laser beam is restored.

Above Grade

(move down)

>2”