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Vintage Telephony and Telecomms Vintage Telephones, Telephony and Telecomms Equipment |
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#1 |
Tetrode
Join Date: Sep 2015
Location: Margate, Kent, UK.
Posts: 56
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Hello
Have just acquired a black 332L telephone. The outer case was in very good nick but a lot of corrosion inside Originally there was no dial tone, but swapped it the handset with a spare one and now working, which I guess means there was a problem with the transmitter. The problem I have now is that it will not ring. If you phone in, you can hear ringing from the other phone, but the phone bell will not ring. If you lift the handset then you can have a conversation. So looks like a problem with the bell unit itself. The bell arm is swinging freely and does not touch both gongs at the same time. I have no idea how to test this, I have a multimeter, but if someone can give me some basic tests to try and work out the problem I would be very grateful |
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#2 |
Dekatron
Join Date: Jul 2007
Location: Penrith, Cumbria, UK.
Posts: 3,687
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Hi John,
First of all, has your telephone been converted to plug and socket as per this diagram? And are all the appropriate links in place? Term. 1 - term 2 strapped; Term. 11 - term 12 strapped. Break between terms. 10 - 11; Leave a strap in place of the 3k3 resistor for now, if one is fitted. You'll need to start with measuring the d.c. resistance across your bell-bobbins, then measure back between terminal 12 and terminal 2 for 1000 Ohms d.c. Make sure your handset is on rest when you do it. Your bobbins should measure about 500 Ohm each; 1000 Ohm the pair. Check this and report back.
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Regds, Russell W. B. G4YLI. |
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#3 |
Dekatron
Join Date: Feb 2005
Location: West Cumbria (CA13), UK
Posts: 6,130
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It may be that the ringer isn't wired correctly. Any chance of a picture of the internal wiring?
As to the original handset problem, it may be (as you say) that the transmitter was failing to make a loop (either the inset or its wiring open-circuit) or it may be that the receiver or its wiring is o/c. The way to distinguish would be either to check the resistance between the red lead of the disconnected handset and respectively the white (transmitter) and green (receiver) leads and see which is o/c. Alternatively, reconnect the faulty handset and 'phone in to the telephone with the handset off-hook. If it is failing to make a loop, the other 'phone should continue to receive ringing tone and a burr-burr should be audible in the receiver of the faulty 'phone. If the receiver is at fault, the other 'phone should receive engaged tone. edit: as usual another post has been made while I was composing mine.
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Mending is better than Ending (cf Brave New World by Aldous Huxley) |
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#4 |
Octode
Join Date: Mar 2011
Location: Sheffield, South Yorkshire, UK.
Posts: 1,453
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There's a picture, rather than a diagram, of what the terminal block should look like here: https://4.bp.blogspot.com/_TfdvweZZ1...conversion.jpg
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#5 |
Tetrode
Join Date: Sep 2015
Location: Margate, Kent, UK.
Posts: 56
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Hello
Have checked the wiring and it is definitely correct Not much experience with a multimeter but this is what I did My multimeter does not have a setting for 500 ohms, I can get a reading with 200 ohms but not with 2000 ohms which is the next setting up. so I tested across the bobbins (which I assume is the two points where the blue connecting wire is soldered). I get a reading of around 0.4 for this. I then tested between terminal two and where the green wire meets the bell bobbin. I then tested between terminal 12 and where the orange wire meets the bobbin I am getting readings of around 0.3 for both of these. I then did the same tests with another phone which is in full working order, The results were very similar. The tests were done while phone resting i.e. the handset was on. Hope I have done this properly. Many thanks for reading |
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#6 |
Dekatron
Join Date: Jul 2007
Location: Penrith, Cumbria, UK.
Posts: 3,687
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What sort of multimeter are you using?
I don't know how your colours go but here's a pic of mine. You should measure between the green and orange wires to the bell-movement, ie: the ones that aren't the bobbin connecting wire. The bobbins are connected in series and the link goes from Left-hand to left-hand (or right-hand to right-hand) as per photo. Handset on rest. You should get around 1000 Ohms. Then try measuring between terminals 2 and 12. You should get around 1000 Ohms here too. If not, measure between the green wire and terminal 2. It should be continuous (short cct on your meter). Then same between the orange wire and terminal 12. It, too should be continuous. This establishes your bell movement connection to the terminal block. Do this then report back. Until I know more about your meter and the Ohms range, I can't be more specific.
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Regds, Russell W. B. G4YLI. |
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#7 |
Tetrode
Join Date: Sep 2015
Location: Margate, Kent, UK.
Posts: 56
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Hello
I attach a picture of the multimeter I am using. The resistance settings are 20 and then 2000, so have set it to 2000 as I assume this will measure anything from 20 to 2000 If I put the probes across the orange and green wires going to the bell I get no change on the meter whatsoever, it stays on the reading on the picture(1.). If I do it on a fully functioning phone I get 1.011 which is assume is 1011ohms which is roughly correct. If I put the probes on term 2 and then the green connection at the bell I get a reading of 0.00 and likewise for term 12 and the orange wire. I also get a reading of 0.00 if i put the probes across term 2 and 12 I am guessing all that means that there is no power going to the bell Anyway kindly let me know if I am on the right lines and thanks once again |
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#8 |
Dekatron
Join Date: Feb 2005
Location: West Cumbria (CA13), UK
Posts: 6,130
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It sounds as though the connections to the bell are fine but you have an open circuit (o/c) coil in your bell motor.
If you check between the wire linking the two coils (blue in the image) with each of the other coil connections in turn, you should get a reading of around 0.5 (KΩ) to one terminal and o/c to the other (the reading shown above). As a quick and dirty bodge for testing that everything else is OK you could try shorting out the o/c coil with a piece of wire (assuming your conversion already includes a series resistor) and you should get some sort of ringing by means of the remaining coil. Don't try running the telephone like this though. The only way forward (unless you fancy rewinding the o/c coil) is to replace the bell motor if you want a telephone that rings on an incoming call.
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Mending is better than Ending (cf Brave New World by Aldous Huxley) |
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#9 |
Dekatron
Join Date: Jul 2007
Location: Penrith, Cumbria, UK.
Posts: 3,687
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I've successfully repaired bell bobbins in the past, as I've found they usually (but not always by any means!) fail at the ends near the terminals. It's a bit fiddly but can be done.
The good thing is the Type 59A bell is ubiquitous and you should be able to acquire a spare readily enough, even if it's from a more modern telephone. The tags might be at the other end but it should still go in. Or you might be lucky enough to find a 59D bell movement, which has 2000 Ohm bobbins.
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Regds, Russell W. B. G4YLI. |
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#10 |
Tetrode
Join Date: Feb 2009
Location: Caernarfon, Gwynedd, UK.
Posts: 51
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Unfortunately a bell 59A from a 700 series won't fit in a 300 series because the clapper arm comes from underneath rather than above and unlike the earlier ones in the 300 series this doesn't seem to be reversible.
I have probably got a working bobbin somewhere, I'll have a look this afternoon if that's going to help. |
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#11 |
Dekatron
Join Date: Jul 2007
Location: Penrith, Cumbria, UK.
Posts: 3,687
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I should've said the bobbins! You can mix and match them.
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Regds, Russell W. B. G4YLI. |
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#12 |
Tetrode
Join Date: Feb 2009
Location: Caernarfon, Gwynedd, UK.
Posts: 51
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john777, I have found a couple of working bobbins,do you need 1 or 2?
PM me your address and I'll put it/them in the post |
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#13 |
Tetrode
Join Date: Sep 2015
Location: Margate, Kent, UK.
Posts: 56
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Replaced the old bobbins with new ones and low and behold phone now ringing and working very well
Thanks to all those people who contributed |
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#14 |
Dekatron
Join Date: Feb 2005
Location: West Cumbria (CA13), UK
Posts: 6,130
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It's good to know it's sorted.
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Mending is better than Ending (cf Brave New World by Aldous Huxley) |
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#15 |
Dekatron
Join Date: Jul 2007
Location: Penrith, Cumbria, UK.
Posts: 3,687
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Excellent news! Now you can relax and enjoy your telephone, it might be worth taking the old bobbin apart to find out where the break is.
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Regds, Russell W. B. G4YLI. |
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