A20-TX Door Replacement

Sound Devices has identified a small batch of transmitters that was assembled with an adhesive that cannot withstand the forces exerted on it by the battery door’s neodymium magnets. Sound Devices is committed to providing a reliable, long-term fix by providing customers with an improved preassembled door kit. 

The left door magnet is needed for proper operation of the A20-TX. If the magnet is missing or installed backwards, some of the transmitter’s functions will be disabled, including the battery charger. Note: The right-side door magnet does not affect the electrical functionality of the transmitter. 

Locate the magnets in the battery door. If the magnet is silver in color, you qualify for an A20-TX door replacement kit. Your device will not require a battery door assembly if the magnet has a black epoxy coating.

Magnet Location

Silver Magnet with Inferior Adhesive

Epoxy Coated Magnet with Improved Adhesive

P/N 29663 Door Kit contains the following items:

  • P/N 29459 Preassembled door assembly, qty =1 
  • P/N 29511 T5 Torx driver bit, qty = 1
  • P/N 29662 Blue threadlocker packet, qty =1 
  • P/N 28364 Hinge pin, qty = 2 

Preassembled Door

T5 Torx Bit


Door Hinges

Recommended tools (not provided)

  • ¼” nut driver (for T5 Torx driver bit)
  • Tweezers

¼“ Hand Driver


Remove all batteries/power sources from the A20-TX.

Locate the T5 Torx hinge pins located on each side of the battery door.

Hinge pin locations

Hinge pin location, side view

Remove the hinge pin from the transmitter’s door using a T5 Torx bit, as shown below. 

Rotate the bit counter-clockwise until the hinge is loose from the main chassis.

Repeat this process for the hinge pin located on the right side of the door.

Remove the original door (Figure 1). WARNING: Do not disturb the gasket material on either side of the transmitter’s chassis (Figure 2). 

Figure 1

Figure 2

Open the blue threadlocker capsule by removing the white cap and twisting the plastic seal. 

Partially insert the new hinges in the new battery door and apply a small amount of threadlocker to the threads of the hinges.

Below is a closeup photo of threadlocker applied to the hinge pin threads

Snap the battery door into place and tighten the hinge pins by turning the Torx bit clockwise.

Ensure that the latch mechanism works properly by opening/closing the new door several times.

Test the magnet and hall sensor by installing a fresh set of charged batteries.

With the door open and unit powered on, the display should show a menu icon, as shown in Figure 3.

The menu icon should disappear when the door is closed, as shown in Figure 4. 

Figure 3 – Battery door open; menu icon present

Figure 4 – Battery door closed; menu icon absent

Using a pair of tweezers, carefully remove the serial label from the original door and transfer it to the new door.

Door replacement has now been completed.