SB1013 - SSM Battery Polarity Key Block Replacement


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Some SSM users have been experiencing tight fitting batteries in the field. Usually this is evidenced by a minor difficulty in inserting the LB-50 battery into the housing tray between its alignment rails when with the battery properly oriented. We have found that some units shipped with slightly discrepant Battery Polarity Key Blocks that did not seat correctly with the housing upon installation and which can thereby manifest an interference fit with the battery in the “keyed” corner. This interference can cause a tearing of the battery’s outer insulation film on its side which, in extreme instances, can lead to battery shorting to the housing. The 27078-1 part has since been redesigned to solve this problem.

SB1013 EquipmentNeededFor SSM transmitters that exhibit this behavior, follow the five steps below to replace the polarity key block. Equipment needed:

  • Battery Polarity Key Block; P/N 27078-1 (revision C)
  • .050 Hex Key; P/N 35700
  • Clear Silicone RTV
  • Syringe w/micro tip
  • Toothpick(s)
  • Cotton swab(s) or cloth wiper

Step 1

Open the battery door and remove the battery.

SB1013 Step1

Step 2

From the battery compartment’s right hand side, use the hex key to loosen and extract the 28913 capscrew that fastens the polarity key block to the housing there. Wipe away any residual cured RTV from the capscrew and set it aside. Pry the polarity key block away from the housing if necessary, with a toothpick and discard the part. Wipe the affected area on the housing clean with an alcohol-soaked cotton swab or cloth wiper.

SB1013 Step2

Step 3

Insert a small amount of clear silicone RTV into the syringe. Squeeze a bit out to ensure the tip is full. Wipe the tip clean and then insert it into the threaded hole where the capscrew was removed. Squeeze a very small amount of RTV into the hole. Wipe away any excess RTV from the housing surface.

 SB1013 Step3

Step 4

Install the new polarity key block onto the housing as shown below. Rotate the hex key clockwise to tighten the capscrew, but be careful not to overtighten it. Verify that the head of the capscrew seats well within the counterbore in the polarity key block and that the polarity key block seats squarely and completely within the curved recess in the housing. Wipe away any excess RTV from the housing and polarity key block surfaces.

 SB1013 Step4

Step 5

Reinsert the battery into the unit observing the proper keyed orientation. The battery fit should be slightly snug side-to-side between alignment tabs but not tight. Process is complete