332 Conversion Help

[loopy66]

Hi. I have a telephone, labelled on the inside as "No. 332 (Mark 1). It was produced by ATM; long story short, it is this phone : http://www.britishtelephones.com/atm/l11560.htm

I am trying to convert it following online instructions and I have attached an image to this thread of the connections.

My problem is, the phone does nothing. I following some advice in another thread on this forum so have done the following...

1) I disconnected the green handset wire from T6 and measured resistance between the red and green of handset wires and got about 80 ohms.

2) Reconnected the green handset wire to T6. The phone was plugged into the wall and connected T4 and T5 to short the mic. but this did nothing, no dial tone still.

The phone line is working as I have tested it with a working phone.

Any ideas of further tests or possible problems?

[russell_w_b]

Have you shorted T8 to T4 to by-pass the dial pulse contacts? Have you a multimeter?

[russell_w_b]

...And are you absolutely sure that the wires connected up to the terminal block from your lead go to your BT standard plug as follows? You seem to have a green, yellow and black in there too.

Red to pin 5.
White to pin 2.
Blue to pin 4.

All pins referenced to you looking at the plug with the pins uppermost and pointing away from you.

Welcome to the forum, BTW!

[loopy66]

Hi Russell. I have just shorted T8 and T4 as you said and got no response or change at all.

I do have a multimeter and whilst there just now I check the voltage across T1 & T9 (where I have the white and red line wires) and it showed a stable AC reading at 00.50v but when I rang the line it would go to 00.60v on and off in time with where one would expect the bell to actually make noise. Not sure if this is of any relevance but worth putting in here just in case.

[Station X]

Something wrong there. Line voltage should be around 50 Volts DC with the handset on hook.

Ringing voltage is AC and should be about 80 Volts.

[loopy66]

I just looked at the plug end of the line wire and it looks not right at all. I'm going to crimp a new plug on with the colours in the correct order and kick myself really hard if this is the issue and I didn't even think to check that. I will post back.

[russell_w_b]

Here's a circuit diagram with connections to the BT plug. You need to make the loop from the red wire to the white wire (plug pins 5 and 2) when you lift the handset off rest.

When you lift the receiver, the plunger switch contacts 1-2 and 3-4 close. Contacts 1-2 make your loop and operate a relay at the exchange. The line voltage then drops to about 9 - 12V d.c. or so (from 50V d.c. 'on-hook' voltage) and you should get dial tone.

You need to check continuity round the loop starting at terminal 1 to 5 through your induction coil (35 Ohms); 5 to 4 through your mic (250-ish Ohms to 1500-ish Ohms); 4 to 8 across your dial pulse contacts (short-cct).

Make a note of the readings and report back. What sort of multimeter are you using?

[loopy66]

The yellow and black wires are not connected to anything by the way and will be stripped back to be totally out of the way.

Anyway, update since my last. It seems that the line wire was not in the right order. I just took the cable out of a packet and trusted it. Lesson learned there

I crimped on a new plug with the wires in the correct order and the phone is now flying... dial tone and the ring sounds lovely. The call quality is pretty good too.

Many thanks for the help guys. I am off to kick myself pretty damn hard for not checking the plug wire sequence.

[russell_w_b]

Sorry - that drawing was a bit small! Try this one...

[russell_w_b]

Originally Posted by loopy66

Anyway, update since my last. It seems that the line wire was not in the right order. I just took the cable out of a packet and trusted it. Lesson learned there

Pleased you got sorted. I've been there with the dodgy lead too...

[Dave Moll]

By the way, your mention of yellow and black wires makes me think that the alternative black/red/green/yellow convention was used in your lead, rather than the more normal white/green/blue/red, in which case the usage is usually:
black = A leg (normally white)
red = not used (normally green)
green = ringer (if not using internal capacitor - normally blue)
yellow = B leg (normally red)

Obviously, if your plug is now wired differently, this will not prevent the 'phone working correctly as long as the correct plug position goes to the correct terminal in the 'phone.

[loopy66]

You are correct, Dave Moll. Using the ideas from the guys I checked the wires and they didn't match up to normal and the colours you listed were exactly the difference. I could have re-wired the phone side like this but wanted the normal colours to match so that if I come to the phone in a years time or even more then I won't be scratching my head with non normal wiring so I just re-crimped to make it easy for the future.

However, now the phone is in use I want to clean it up and i'm thinking the white outer sleeve of the cable is ruining the effect so will change shortly to a black one and i'll be careful to choose the normal internal colour sequence this time

The wife is debating with me whether I should clean it up though as she likes it looking old and used. Hopefully I win the debate because I want it looking as good as it once did.

[russell_w_b]

You can get coloured leads (inc. black) with square grommets and proper spade terminals fitted from Ray Sutcliffe at www.gpospares.co.uk

Trouble is, he's been 'off line' for a bit. Is he still trading, anyone?

[Pellseinydd]

See the black cords with PSTN plug on specifically designed for 200/300 type phones with tie cords at the telephone end - see eBay item 182112563728 http://www.ebay.co.uk/itm/gpo-200-30...QAAOSwjVVVn15R

Cords I've had from this seller have presented no problems.

Another option is to fit a plaited line cord and Bakelite Block Terminal No 20/4 to which a shortened modern line cord as above is connected - making the phone look more like the original. Just ensure the colours match.

Ian

[ThePillenwerfer]

Originally Posted by russell_w_b

Trouble is, he's been 'off line' for a bit. Is he still trading, anyone?

For "a bit" read eighteen months. People were asking about him on here last year and we learnt that he was seriously ill. See: https://www.vintage-radio.net/forum/...d.php?p=779436

— Joe

[Nickthedentist]

Originally Posted by russell_w_b

Trouble is, he's been 'off line' for a bit. Is he still trading, anyone?

Last time I spoke to him, he was seriously ill, I'm afraid.