Monday, 06 November 2006

• Fitting a new electret type 21 transmitter to old British Bakelite telephones.

   A few people have asked me how to do this so I have included instructions below.

  Step 1) Remove the base plate of the telephone

  

  Picture 1 shows the inside of the telephone once you have removed the base plate (4 screws in the corners)

  Notice the numbering of the terminals (the important ones are T4, T5 and T6.

  Step 2) Inside the telephone check the 3 wire cord is correctly installed (white from T4, Red from T5 and green on T6)

  Step 3) Remove the mouthpiece cover by VERY carefully inserting a thin prong into the hole and carefully twisting the mouthpiece anticlockwise as in picture 3.

  

   

  Step 4) Lift out the old carbon granule microphone/transmitter as in picture 4.

  

  Step 5) Unscrew and remove the spring contacts as in picture 5.

  

  

   

  Step 7) Connect the new microphone (transmitter) to the new cord Red and the White wires as in picture 7.

  

  Step 8) Connect the Green wire as in picture 8 (note this the strap wire link to the red wire I have called this Blue in picture 8).

  

  Step 9) Use some form of soft packing behind the new (smaller) microphone to prevent rattling.

  

  Step 10) Replace the mouthpiece gently (can be easily damaged). As a finishing touch clean and polish with Bakelite Polish from Greygates.

  • 11:19 AM
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