Tuesday, March 20, 2012

Changing the Microphone in a Bakelite Telephone

Old British Bakelite Telephones such as the 200 series and 300 series telephones used the same handset. This Bakelite handset was known as a model no 164 handset, and was used for over 30 years. It was the standard telephone handset in 1929 and was manufactured all the way through to the early 1960's.

Compared to today’s modern telephone handsets it has a very good ear piece (or receiver). Its only weakness is that the microphone (or transmitter) in the mouthpiece does not live up to today’s expectations of sound quality. This lack of sound quality is only noticeable to the people at the other end of the telephone call. When you are using one of these antique telephones the person at the far end will think you are calling them from the bottom of a well :-) This can be rectified by swapping the old carbon granule microphone out with a modern electronic (electret) microphone. Several makes of replacement electret microphones are available however they must be designed for use in old telephones.

The instructions below show you how this microphone change can be performed.

1) First remove the Bakelite mouthpiece from the handset. If you are unsure how to remove it safely, please see the details on our web page removal of a bakelite mouthpiece.

2) The old Carbon Granule Microphone should just lift out (it is not hard wired).

3) Use a small flat bladed screwdriver to remove the old microphones spring clips (see photographs below).

4 ) Attach two wires to the new electronic microphone ideally red and white wire should be used to make life easier when you fit it (see photograph below). Thankfully new electret microphones used in these vintage telephones are not polarity sensitive, so it does not matter which way round you connect the wires.

5) Connect the new red wire from the microphone to the old red wire inside the mouthpiece, and the new white wire to the old white wire inside the telephone mouthpiece.

6) Modern electronic microphones are smaller than the old carbon granule ones, so you will usually need to cut a small piece of foam to fill the gap to stop the new microphone from rattling around inside the old telephone handset.

7) Finally refit the Bakelite mouthpiece on your handset and test the Bakelite telephone.

Providing the rest of your antique telephone is in good order, the sound quality and usability of your old Bakelite Telephone should be significantly improved.

Tuesday, January 24, 2012

Fitting a 1960's or 1970's Vintage Wall Telephone (Part 1).

This is an explanation of how to physically fit, or safely remove British 1960's (model No 711) or 1970's-1980's (model 741) vintage wall telephones to a wall.

1) The fist step is to locate and unscrew (half way out) the telephone case retaining screw on the bottom of the wall telephone. See the pictures below.

2) Next carefully lift the case starting from the bottom of the telephone, as it hinges at the top (however keep the telephone case parallel to the base plate). This can be tricky if you have not done it before.

TIP: It helps if you hold the telephone switch hooks down and press gently down on the vintage telephone dial while lifting the case from the bottom. See the position of my hands in the diagram below.

3) The vintage wall phone case should now lift completely off. See diagrams of the telephone below.

4) The retaining screw for the separate metal T shaped wall fitting is a single bolt/screw at the bottom, however it is hidden behind where the curly handset cord enters the telephone. So you need to slide the telephone handset cable grommet to the right, as shown below.

5) You should now be able to unscrew the single bolt that holds the T shaped bar to the vintage telephone. As shown below.

6) The telephone is hinged a the top, so simply lift from the bottom as shown above.

7) With the T shaped bar separate fit this to your wall with the appropriate screws for the type of wall it needs to fix onto.

8) Slide the curly handset cable grommet back into its original position.

9) The 741 or 711 Telephone can then be hung onto the T bracket at the top, and the retaining bolt tightened at the bottom.

10) Refit the wall telephone case, making sure the cut out in the plastic dial surround ring is in line with the metal finger stop, see below.

Tip: Holding the switch hooks down and pressing on the dial usually makes fitting the case easier.

11) Finally tighten the case retaining screw at the bottom.

12) These instruction should help, either remove these old telephones from the wall or fit them to a new position.

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