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Vintage Telephony and Telecomms Vintage Telephones, Telephony and Telecomms Equipment |
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28th Aug 2020, 4:09 pm | #1 |
Tetrode
Join Date: Sep 2015
Location: Margate, Kent, UK.
Posts: 56
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Problem with dial 24c dial making clicking noises on 232 telephone
Hello
I have a 232 bakelite phone with a type 24c dial on. It is working correctly, I can dial out and dial in and sound quality pretty good. The only problem is when I dial out I can hear a clicking sound which is not nice on the ear. Does anyone know what could be causing this and whether it can be cured. I know later phones were fitted with a rectifier to stop this but is it possible to fit this on a 232? Many thanks for reading |
28th Aug 2020, 5:40 pm | #2 |
Triode
Join Date: Jul 2020
Location: Dallas, Texas, USA.
Posts: 11
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Re: Problem with dial 24c dial making clicking noises on 232 telephone
I don't know the 232 phone, but it is all about space... for the double diode pop reducer.
if there is room. across the rec screws. or inside the phone? or maybe the dial contacts need attention? or a different switch config? |
28th Aug 2020, 5:45 pm | #3 |
Pentode
Join Date: Jan 2019
Location: Manchester, UK.
Posts: 163
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Re: Problem with dial 24c dial making clicking noises on 232 telephone
It could be the dial contacts that need a clean, there are dial off normal contacts (these make when the dial is off normal) which short out the transmission components.
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28th Aug 2020, 5:46 pm | #4 |
Dekatron
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 5,208
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Re: Problem with dial 24c dial making clicking noises on 232 telephone
I am not sure what the Dial 24C is, but I am assuming it's the same electrically as the dial normally used in the Telephone 232.
In which case try cleaning the off-normal contacts (the ones that close when the dial turned from the rest position). One pair of contacts short-circuits the receive to prevent said clicks. DO NOT use abrasive, you will ruin the contacts. I normally cut a thin strip of paper, soak it in isopropyl alcohol (propan-2-ol), put it in the gap between the contacts, turn the dial so the contacts close, and pull the paper out. There's then a dark streak on the paper... Repeat a few times and see if things improve. |
28th Aug 2020, 5:47 pm | #5 |
Heptode
Join Date: Jan 2008
Location: Hakadal, Norway
Posts: 643
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Re: Problem with dial 24c dial making clicking noises on 232 telephone
The dial has some shorting contacts shorting out the circuit, so you should only hear a click when the dial is moved out of rest position, and one when it is coming to the rest position. The diode bridge may fit in the phone across the wires going to the receiver.
The diode bridge will fit between the 2 terminals inside the ring. dsk |
28th Aug 2020, 6:43 pm | #6 | |
Heptode
Join Date: Jul 2007
Location: Flintshire, UK.
Posts: 707
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Re: Problem with dial 24c dial making clicking noises on 232 telephone
Quote:
The 24C is/was said never to have been adopted by the GPO . I've never come across reference to it in any GPO Documentation. However I have a Tele 16 that had been converted by the GPO for automatic working but had never been used when I bought it many years ago - it still had two screws wrapped in brown paper tied to the terminal block in good old GPO fashion!. It has a Dial 24C fitted and that has 'GPO' stamped in yellow paint on the rear - the dial that is, not the phone! The circuit should be that of a Tele 232 even if it is an AT&E version see GPO circuit diagram N332 for the Tele 232.. With a test meter set to ohms, you should get a complete short between Terminal 4 and Terminal 7, and between Terminal 6 and 7 when the dial is held 'off normal' . That is after cleaning the contacts as suggested. That should show which of the contacts is the problem. Could be a faulty dial cord - not unknown! Last edited by Pellseinydd; 28th Aug 2020 at 6:50 pm. |
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28th Aug 2020, 6:52 pm | #7 | |
Heptode
Join Date: Jul 2007
Location: Flintshire, UK.
Posts: 707
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Re: Problem with dial 24c dial making clicking noises on 232 telephone
Quote:
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28th Aug 2020, 8:57 pm | #8 | ||
Heptode
Join Date: Jan 2008
Location: Hakadal, Norway
Posts: 643
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Re: Problem with dial 24c dial making clicking noises on 232 telephone
Quote:
dsk |
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28th Aug 2020, 10:04 pm | #9 |
Dekatron
Join Date: Feb 2005
Location: West Cumbria (CA13), UK
Posts: 6,127
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Re: Problem with dial 24c dial making clicking noises on 232 telephone
Yes, the N diagram confirms that T6 and T8 were reversed on earlier versions such that the receiver was connected between T5 and T6 - as shown in the paster diagram posted by DSK earlier.
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Mending is better than Ending (cf Brave New World by Aldous Huxley) |
11th Sep 2020, 2:27 pm | #10 |
Tetrode
Join Date: Sep 2015
Location: Margate, Kent, UK.
Posts: 56
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Re: Problem with dial 24c dial making clicking noises on 232 telephone
hello
Basically cleaned all the points on the dial, did not have any alcohol so used meths. There was an immediate improvement. So looks like job done Many thanks to all those people who took the trouble to reply |