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MPX-LPD Display Replacement Instructions

These instructions detail how to replace the embedded LPD display in the MPX magnetostrictive float level transmitter.

When you’re done, you can use the box that the new components came in to send us the old ones. Keep it handy if possible.

If you have any questions at all throughout this process, please contact Gordon Greathouse at 888-525-7300 ext. 1008, or via email at

Step 1: Turn off power & remove current display

Before you begin, make sure the power has been turned off for your safety. Once it is powered down, remove the lid from the aluminum housing by twisting in a counter-clockwise direction.

Next, raise the LPD display from off its seat inside the housing. You may need to use a small flat head screwdriver to carefully pry the display up.

Expose the black and red wires connecting the LPD display to the MPX transmitter.

The black wire is connected with a white connector, which you’ll want to remove with the display. Loosen the screw that holds the MPX’s black wire so that the connector comes off along with the display.

The red wire is connected to a connector on the electronics cup. This connector will stay on the MPX; simply loosen the screw that holds the display’s red wire.

Note: you may have a blue 2-pin connector, or a green 4-pin connector on your unit. Either way, remove the display’s red wire.

The LPD display will now be detached from the MPX.

Step 2: Replace the display and lid with the new taller versions

You will have received two new parts: a new LPD display (part number 125788-0004) and a new housing lid (part number 131368-0011). The new display will come with its own white connector.

The new display and housing lid are noticeably taller than their predecessors. This is to make sure all components fit properly inside the housing and eliminate any chance of damage or malfunction.

Connect the LPD display’s black wire to the MPX’s black wire, using the supplied white connector. Insert the MPX’s black wire into the empty side of the white connector and tighten the screw.

Make sure the connection is snug and does not slip before moving on.

Next, insert the red wire into the electronics connector. This connector sits on either two or four pins with labels.

The red wire must be inserted into the terminal labeled “OUT”. Whatever the orientation of the connector, make sure the LPD display’s red wire connects to the OUT terminal. Once inserted into the right location, tighten the screw.

Make sure the connection is secure before moving on.

Finally, place the new LPD display back onto its seat inside the MPX housing. Make sure you place the display with the logo on the top. To avoid pinching wires, carefully tuck the wires safely into the housing as you go.

Once the display is firmly in place, install the new lid by screwing it in place.

The replacement is now complete.

Step 3: Package the old components and send them back to APG

Use the box from the new components to package the old components for shipment to APG. Contact Gordon Greathouse for return shipping information at 888-525-7300 ext. 1008. You can also reach him via email at

Our shipping address is:

Automation Products Group, Inc.
1025 West 1700 North
Logan Utah, 84321

We are committed to ensuring that your sensor works properly for you, and that these problems never happen again. Please accept our apologies and we welcome your candid feedback.