Centenary Neophone
PST Conversion


The Centenary Neophone can be converted to Plug and Socket except for the standard telephone (wired to diagram T.29849 - Schematic A) where there are two methods of conversion.

 

Standard Telephone (Diagram T.29849 - Schematic A)

There are two ways to convert this and they are described below:-
  1. The capacitor will have to be physically removed as it is fitted to a circuit board (un-solder) and a new wire soldered to one of the tracks.  This makes the phone non-standard.
  2. The capacitor is short circuited by a soldered piece of wire and one of the dial leads is removed and connected to the line cord.  This retains the telephone as close to original and it is easier to convert back to standard than method 1.

You have to make your mind up as to which method you favour.

Please be aware that the Type A circuit board terminals are numbered as if all the terminals are in situ.  Terminals 1 and 3 will be missing and two holes will be seen instead.  See the Centenary Neophone page for more information.

 Method 1 - Capacitor fully removed

  1. Remove the original line cord.
  2. White of the new line cord to 4.
  3. Red of new line line cord to 7.
  4. Remove capacitor.
  5. Solder one end of a piece of wire to the circuit board track, where the capacitor was removed.  There will be two holes - it's the track that goes to one lead of the bell ringer.
  6. Connect the blue of the new line cord to the other end of this new wire and insulate fully.
  7. Remove the wire strap above terminals 4 & 5.
  8. Insert a 3.3k resistor between terminals 4 & 5.
  9. Green of the new line cord is not connected and should be insulated.
  10. If a rectifier element is to be installed fit on terminals 6 & 2.

Method 2 - Capacitor short circuited

  1. Remove the original line cord
  2. White of the new line cord to 4.
  3. Remove the orange dial lead wire from dial terminal 3 and connect to the Red of the new line cord. Insulate fully this connection as it not terminated.
  4. Short circuit capacitor with a piece of wire soldered across the capacitor terminals.
  5. Connect the blue of the new line cord to terminal 7.
  6. Remove the wire strap above terminals 4 & 5.
  7. Insert a 3.3k resistor between terminals 4 & 5.
  8. Green of the new line cord is not connected and should be insulated.
  9. If a rectifier element is to be installed fit on terminals 6 & 2.

 

Kingston Communication variant 904 & 908 (Diagram T.34320)

  1. Completely remove the old line cord from all connected terminals.

  2. Either remove Metal Can 1.8uF capacitor from PCB or remove links marked like upside down horseshoe with line through (there are two of these) - it would be better to remove the links.

  3. Connect red wire of new line cord to terminal 7.

  4. Connect blue wire of new line cord to terminal 8.

  5. Connect white wire of new line cord to terminal 3.

  6. Insulate green wire of new line cord as it is not used.

  7. Connect a 3.3k ohm resistor across terminals 3 and E (5).
  8. If a rectifier element is to be installed fit on terminals 1 & 6 - or directly to the terminals of the earpiece.

 

AEI Variant (Diagram T.34357)

  1. Completely remove the old line cord from all connected terminals.

  2. Either remove Metal Can 1.8uF capacitor from PCB or remove links marked like upside down horseshoe with line through (there are two of these) - it would be better to remove the links.

  3. Ensure that a link exists between terminals 3 and 4 (a 1000 ohm resistor should really replace this link, but in most circumstances that would not be necessary).

  4. Connect red wire of new line cord to terminal 7.

  5. Connect blue wire of new line cord to terminal 8.

  6. Connect white wire of new line cord to terminal 3.

  7. Insulate green wire of new line cord as it is not used.

  8. If a rectifier element is to be installed fit on terminals 1 & 6 - or directly to the terminals of the earpiece.

 

 
 
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Last revised: May 09, 2013

FM2