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Old 1st Feb 2021, 10:06 pm   #1
cjmurphy111
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Default Belgian Bell Telephone Fault

I have recently bought a Belgian Bell telephone which is misbehaving. I am new to vintage phones, but have just successfully converted/repaired a 332F, now our primary phone at home. As a mechanical engineer electrics are a bit of a mystery to me, but I'm persevering...

Back to the telephone - it rings and receives call fine (if a bit crackly), has dial tone, but if I try to dial out the dial tone continues after some of the dial turns (but not others), meaning the number is not recognised.

The telephone came with paperwork showing it was professionally converted by a shop called "Classic Telephony" back in 1991 and was serviced/repaired in 2018. It was sold as working, but was not brilliantly packed when it arrived in the post...

Before I take it apart, has anyone got any ideas what the problem could be?

Many thanks!
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Old 2nd Feb 2021, 12:07 am   #2
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Default Re: Belgian Bell Telephone Fault

When you say you have a working tele 332 "at home", are you trying this Belgian phone at the same address?

I ask because some LLU lines (Sky and TalkTalk) only respond to DTMF dialling and not the legacy pulse dials. It's an issue that comes up more and more often on forums like this.
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Old 2nd Feb 2021, 8:44 am   #3
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Default Re: Belgian Bell Telephone Fault

It is possible, assuming as Graham says, that your telephone provider accepts loop disconnect (pulse) dialling, that the problem is a mechanical one in that the dial speed is outside the tolerance accepted by your provider. Not only is the acceptance of LD dialling not universal, but some providers that do support it are more picky than others.
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Old 2nd Feb 2021, 7:27 pm   #4
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Default Re: Belgian Bell Telephone Fault

Thanks for the replies. Yes the 332 is in the same house as the new phone; no problem with the 332 dialling out. Both phones ring when there's an incoming call. We have Sky, but not fibre, if that makes a difference?
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Old 2nd Feb 2021, 8:57 pm   #5
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Default Re: Belgian Bell Telephone Fault

cj- others with more memory of dials wil be along to provide more detail . I'm writing this from memory of GPO courses some 50+ years ago, so I may be a bit rusty. GPO dials consisted of a set of contacts designed to short out the telephone when thje dial was moved off normal and a set of contacts designed to make and break the telephone loop according to the the number dialed. All this is controlled by the mechanism on the rear of the dial . Rotate the dial and the "off normal contacts " make, shorting out the tele to provide a good loop to line and prevent the user getting clicks in the earpiece. As the dial returns to normal the dial contacts make and break the loop to send out pulses as per the number dialled. If you google
Simple way to prove that your line supports pulse ( something you know as the 332 dials out ) is to lift ther handset and tap the cradle . This should break dial tone. As an aside, all of the phones I worked on had a diagram inside. Might just be that the Belgians did likewise.
https://www.google.com/search?q=labe...B6SsUnISGYzBaM

may help explain the mechanicals
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Old 2nd Feb 2021, 9:50 pm   #6
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Default Re: Belgian Bell Telephone Fault

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Originally Posted by Oldcodger View Post
cjSimple way to prove that your line supports pulse ( something you know as the 332 dials out ) is to lift ther handset and tap the cradle . This should break dial tone.
Be careful when doing this it's all too easy to pulse out 112 and you will not be popular.
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Old 2nd Feb 2021, 10:01 pm   #7
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Default Re: Belgian Bell Telephone Fault

Can you turn both Bell and 332 dials simultaneously to 0, let them go, and see if they return at the same time?
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Old 2nd Feb 2021, 10:56 pm   #8
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Default Re: Belgian Bell Telephone Fault

Quote:
Originally Posted by Station X View Post
Quote:
Originally Posted by Oldcodger View Post
cjSimple way to prove that your line supports pulse ( something you know as the 332 dials out ) is to lift ther handset and tap the cradle . This should break dial tone.
Be careful when doing this it's all too easy to pulse out 112 and you will not be popular.
I've never had that problem with simple switch hook taps.
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Old 3rd Feb 2021, 10:58 am   #9
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Default Re: Belgian Bell Telephone Fault

Even if the dial pulse speed is correct (1 second for digit 0 at 10 pulses per second) it could be that the make/break ratio (33.3mS/66.6mS) isn't correct, which, without test gear, is more difficult to adjust than speed. As has already been mentioned some line providers are more ctritical of speed and pulse ratios than others.
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Old 3rd Feb 2021, 1:35 pm   #10
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Default Re: Belgian Bell Telephone Fault

Happily you are a mechanical engineer, and the dial is mechanical.
The speed is held as a combination of a centrifugal regulator and a spring.
It is important to clean the mechanics if it is dirty, oil carefully with silicone free oil, but not the centrifugal break. The speed will usually be OK between 10 and 12 pulses pr second.

How to measure?
Try to read this: http://www.classicrotaryphones.com/f...5673#msg175673

dsk
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Old 3rd Feb 2021, 2:30 pm   #11
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Default Re: Belgian Bell Telephone Fault

In this instance I think Russell's suggestion of a race with the working 332 is probably the simplest approach for dial speed. If the 332 wins, then the Belgian 'phone's dial is too slow.

The Audacity approach in the link, or an oscilloscope, would be the way to go for checking the make-to-break ratio.
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Old 3rd Feb 2021, 8:43 pm   #12
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Default Re: Belgian Bell Telephone Fault

Quote:
Originally Posted by Dave Moll View Post

The Audacity approach in the link, or an oscilloscope, would be the way to go for checking the make-to-break ratio.
I suppose you could use an AVO or other analogue multimeter on Ohms across the pulse contacts and obtain a mean level on the pointer for a known 'good' dial. Comparison with the suspect dial would betray whether there was too much mark or space as the meter pointer tended right or left of the meter position for the good one.
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Old 4th Feb 2021, 10:45 pm   #13
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Default Re: Belgian Bell Telephone Fault

i forgot to mention "ye olde field speed test ". Rotate dial to "0" release and start the chant " One hundred, one thousand and one". At one, the dial should have returned to rest.
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Old 7th Feb 2021, 9:41 pm   #14
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Default Re: Belgian Bell Telephone Fault

Thanks for all the replies. Suspecting it might be a dial problem, I carefully cleaned the mechanism without dis-assembling and very lightly oiled the gears and spring, avoiding the governor. There was no significant obvious dirt or grime.

After this the phone would still not dial out, but I seemed to be able to (mostly) dial a number without the dial tone breaking back in; however, each time the number was not recognised.

I then read the above and tried a race between the two phones - the Belgian dial returns quite a bit quicker than the 332, which I guess could be why the pulses it is generating and not correct? Why would the dial be going too fast?

Many thanks!
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Old 8th Feb 2021, 9:00 am   #15
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Default Re: Belgian Bell Telephone Fault

Quote:
Originally Posted by cjmurphy111 View Post

I then read the above and tried a race between the two phones - the Belgian dial returns quite a bit quicker than the 332, which I guess could be why the pulses it is generating and not correct? Why would the dial be going too fast?
I don't know if the Belgian telephone network required faster pulse trains than the UK network, so can't comment on that. However...

You could slow your dial down by using a pair of flat-nosed pliers (GPO had a name for them) on the arms of the governor by pulling them outwards very gently. There's an instruction here, which might be relevant.

https://www.britishtelephones.com/te...to%20b5125.htm
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Old 8th Feb 2021, 4:58 pm   #16
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Default Re: Belgian Bell Telephone Fault

It may even be that your dial has the correct speed now, and the other one is to slow, and the speed is of less importance.
Not easy to tell. If you could make a recording of the dialing a 0 we could analyze it.

A few things to do:
1) Disconnect the phone.
2) When the phone is in on hook position short the line wires to discharge the ringer capacitor.
3) Connect the 2 line wires to the microphone inlet on you pc's sound-card, go off-hook and record the dialing of a 0 or several 0.
4) Share the sound file, and we may determine how the dial sends the signals.

The Belgian dial should ideally give out a 60% break (about 60 millisec) and 10 such breaks for a 0.
It is always some +/- on such numbers The normal is within +/- 7%, but usually the exchanges tolerated much wider differences, electronic telephone equipment are sometimes programmed with pretty tight tolerances.. maybe because they do not now the mechanics.

dsk

Last edited by dagskarlsen; 8th Feb 2021 at 5:06 pm. Reason: adding text
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Old 8th Feb 2021, 5:12 pm   #17
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Default Re: Belgian Bell Telephone Fault

A dial's make/break ratio can easily be checked using an analogue meter on a low ohms range. Disconnect the phone from the line and connect the A and B wires from the phone to the meter. Turn the dial off normal and zero the meter at the right hand end of the scale. Dial a 0 (ten pulses) and the needle will flicker at around 70% of fsd. Read of the ratio from say a 0-10V scale.
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Old 14th Feb 2021, 6:15 pm   #18
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Default Re: Belgian Bell Telephone Fault

Thanks for the suggestions. Unfortunately I don't have an analogue meter, but I'm sure one of my neighbours does; once we're out of lockdown I'll see if I can borrow it!
In the meantime, it's still receiving calls fine and the wife is quite happy being able to answer calls at her desk, so I'll switch target to one of the many other jobs that need doing around the new (Victorian) house. Thanks for the suggestions and I'll reply if I make any further progress.
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