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Vintage Telephony and Telecomms Vintage Telephones, Telephony and Telecomms Equipment |
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23rd Sep 2014, 5:53 am | #1 |
Hexode
Join Date: Sep 2012
Location: Yorkshire, UK.
Posts: 329
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Bakelite 328 Conversion problems
328 series problem after conversion
Hello all, I just got a 1944 328 series Bakelite Telephone in outstanding condition and have converted it. I have found a couple of issues though. Firstly, after you unplug it and then plug it back in and pick up the receiver I get no dial tone, just a faint electrical buzzing through the receiver. When the bell rings and you pick up to answer all is well and it works. I have to press the plungers down multiple times in order to get a dial tone to come on to dial out. The dial is also extremely crackly and won't register any numbers being inputted, just crackles all the time, bizarrely the dial wasn't connected to anything inside the phone until I wired it, anyone know why that is? |
23rd Sep 2014, 6:41 am | #2 |
Octode
Join Date: Mar 2011
Location: Sheffield, South Yorkshire, UK.
Posts: 1,453
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Re: Bakelite 328 Conversion problems
Sounds like dirty contacts and/or a loose connexion. These certainly need ruling out before investigating deeper.
- Joe |
23rd Sep 2014, 8:02 am | #3 |
Hexode
Join Date: Sep 2012
Location: Yorkshire, UK.
Posts: 329
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Re: Bakelite 328 Conversion problems
Thanks for the reply What would be the best way to clean it's internal contacts? Some sort of electrical contact cleaner?
I think what I am worried about is if it's an induction coil or something which is failing. |
23rd Sep 2014, 8:21 am | #4 |
Heptode
Join Date: Jan 2008
Location: Hakadal, Norway
Posts: 640
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Re: Bakelite 328 Conversion problems
This, and the contacts in the hook-switch would be the first I would look at.
Simple cleaning: take a piece of paper, wet in alcohol, and slide it between the closed contacts, (alchol, meths, isopropanol, methanol...) Dial tuning are a little tricky, but usually not needed. dsk |
23rd Sep 2014, 11:02 am | #5 |
Hexode
Join Date: Sep 2012
Location: Yorkshire, UK.
Posts: 329
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Re: Bakelite 328 Conversion problems
The dial operates very smoothly although not sure if I wired it up properly as It wasn't connected when I took the phone apart and so took the dial cabling out of an old broken 746 I had laying around and did it from memory. Do you know the order the wires should go for the dial?
I have methylated spirits would this work as a sufficient cleaner? Thanks |
23rd Sep 2014, 12:21 pm | #6 |
Dekatron
Join Date: Feb 2005
Location: West Cumbria (CA13), UK
Posts: 6,118
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Re: Bakelite 328 Conversion problems
Have you looked at the wiring diagram at http://www.samhallas.co.uk/repositor...0000/N428.pdf? Does that help at all?
Using a mechanical multimeter set to resistance, you should be able to identify terminals 4 and 5 (the dialling contacts), as turning and releasing the dial with the meter connected across them will cause the meter needle to vibrate as the contacts make and break. Having established these two, terminal 3 can be identified as being shorted to terminal 4 while the dial is off-normal. In this state, terminals 1 and 2 will be shorted to each other as well, but not to anything else. Having identified the five terminals on the dial, wire them up as instructed in the diagram. I hope this helps.
__________________
Mending is better than Ending (cf Brave New World by Aldous Huxley) |
23rd Sep 2014, 12:39 pm | #7 |
Octode
Join Date: Mar 2011
Location: Sheffield, South Yorkshire, UK.
Posts: 1,453
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Re: Bakelite 328 Conversion problems
Meths'll do fine.
Dial connexions shown below. - Joe |
23rd Sep 2014, 1:47 pm | #8 |
Heptode
Join Date: Jan 2008
Location: Hakadal, Norway
Posts: 640
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Re: Bakelite 328 Conversion problems
Yes methylated spirits are great.
The pulsing dial contacts (normally closed) are the really important contacts, te other ones are mainly to suppress noise. dsk |
23rd Sep 2014, 5:34 pm | #9 |
Hexode
Join Date: Sep 2012
Location: Yorkshire, UK.
Posts: 329
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Re: Bakelite 328 Conversion problems
Update:
After a total clean and "blow" with an SLR bulb blower, the phone is working flawlessly. I found the problem, there were two tatty wires which connect the hook switch touching each other, I used a screw driver to bend the solder away from one another and all is well. |
23rd Sep 2014, 6:09 pm | #10 |
Octode
Join Date: Mar 2011
Location: Sheffield, South Yorkshire, UK.
Posts: 1,453
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Re: Bakelite 328 Conversion problems
Jolly good.
- Joe |
24th Sep 2014, 10:00 am | #11 |
Rest in Peace
Join Date: Apr 2012
Location: West London, UK.
Posts: 665
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Re: Bakelite 328 Conversion problems
Hi Ryan,
how about some photos please. Regards - Mike |
3rd Oct 2014, 8:49 pm | #12 |
Hexode
Join Date: Sep 2012
Location: Yorkshire, UK.
Posts: 329
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Re: Bakelite 328 Conversion problems
Hello, here is a phone of the telephone.
Last edited by AC/HL; 3rd Oct 2014 at 10:37 pm. Reason: Image rotated |
3rd Oct 2014, 8:57 pm | #13 |
Heptode
Join Date: Jan 2008
Location: Hakadal, Norway
Posts: 640
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Re: Bakelite 328 Conversion problems
Looks great!
You have a nice one there! dsk |