746 Troubleshooting

[Poppyfields]

Picked up a cheap "not working" 746 in a vintage store (80's version I think). With a new cable I can get a dial tone when plugged in, and after oiling the dial it now turns smoothly. However, the dial cannot call a number (I continue to hear the dial tone) and it makes a mechanical type clicking when dialed.

When I call the phone my mobile shows line engaged and phone does not ring.

I'm not a natural at fixing stuff. My first instinct is to replace the whole dial but am I missing something do I need a new circuit board or to convert anything? Any help appreciated.

[Pvt-telco]

Please show photos of it, but the speed might be set to fast, it could be a connection issue, but we would need to see a photo of it to see what issues there might be.

[mentalstampede]

As far as not dialing out goes, the issue may be with your phone line not recognizing pulse dialing. Many current telephone services, particularly the VOIP types require DTMF "Tone" dialing.

[Poppyfields]

How does do I test this out? Do I call plusnet, my phone provider?

[mentalstampede]

Yes, contacting your provider directly would be the simplest way. If your provider does not support pulse dialing, then the phone will need to be used with a converter device (rotatone, dialgizmo, etc.)  if you want to dial out.

[mentalstampede]

Here is a diagram of how the 746 should be wired. Check to see that all the leads are hooked to the appropriate terminals.

http://www.rotatone.co.uk/wp-content/uploads/2012/05/706-746-8746-Wiring-Diagram-Converted-Only-No-RotaTone1.png

[Ktownphoneco]

I would still check with "Plusnet" as Kenn has suggested, but here is a link to "Antique GPO Phones" in the UK, which states that if your telephone service provider is "Plusnet or Talk-Talk", you require a pulse to tone converter.
Here's the link :  https://www.antiquegpophones.co.uk/shop.php

Scroll down about almost to the bottom of the page, and look under "Information", and read lines 8 & 9.     But I'd verify that directly with "Plusnet" customer support.

Jeff Lamb
   

[Poppyfields]

I'm out of contract with plusnet and can move to BT without any major issue, however I was previously a Talk Talk customer and I'm assuming their LLU upgrading is the issue? In this situation is going to BT likely to prevent the need for converting?

[Poppyfields]

Thanks for the circuit diagram. I'll check my connections.

[twocvbloke]

As a Plusnet customer myself (if you've ever visited the insane asylum that is their forum, you'll have seen me there), I can say that they work over BT's hardware directly as they're wholly owned by BT these days, and their service tends to accept pulse-dialling for the moment, and they won't provide support for it as it's a legacy product that happens to have been left in place...

I'll have a better look at your pictures in a bit (typing this on my smartphone!), could be something simple, as these phones are pretty simple beasts...

[twocvbloke]

Just had a good look, and the phone appears to be wired correctly (there is no Resistor in line with the bell, but that's because yours has a 4000 Ohm ringer, which is a good thing), so two things would come to mind if it's engaging the line with the handset on-hook, either the dial has the contacts in the wrong order or bent out of shape, or the hookswitch (which makes the click when you lift and replace the handset) could be bad, though my money's on the dial as those "fisher-price" dials (all plastic and not very reliable) tend not to last very well, I have one somewhere and it's a nightmare to keep working!! 

Back on the not dialling part, the dial should produce 10 pulses per second (the tapping noises you'll hear in the handset), if you dial a zero and say "One Mississippi" and it takes longer to return or returns too quickly, then it'll not dial properly and result in the issue of not breaking dialtone, as modern telephone exchanges here in the UK are a bit fussy about how accurate the pulse-dial rate received is.

There is also the issue that your local telephone exchange has dropped support for pulse-dialling entirely, which would mean that no matter the provider you went with (BT, Sky, TalkTalk, Plusnet, EE, etc.), it still wouldn't dial out, as the equipment wouldn't understand a pulse-dial signal, leaving only two options of fitting a pulse-to-tone converter (Rotatone, DialGizmo, etc.), or using an office phone system such as a Panasonic KX-T30810BE, but the latter's only useful if you intended to have multiple vintage phones, which passing visitors tend not to...

[Poppyfields]

Great advice there. Really appreciated, Thanks. I'll not be able to do much for a few days as we have family over for Easter. I'll let you know how I get on.

[andy1702]

Where in the world are you Poppyfields? If you're in the US there might be make/break ratio issues with the UK dial on the US system. I know this because I have an ATA box that came with US settings and it has great trouble understanding the pulses from UK phones until they are adjusted.

If you're in the UK you should be able to plug your phone into the PSTN and whatever provider you are with it should work. As I understand it (although I could be wrong) UK PSTN providers have to make provision for legacy GPO equipment, so all have to support pulse dialling.

Because your 746 appears engaged when you call from another phone, I'd say either the hook switch or possibly the line cord may be faulty. You say you fitted a new line cord. Did you check each wire individually on the new cord with a multi-meter? I sometimes find one of the wires not connecting as it should. Thisbis normally a fault in the crimping of the plug onto the end of the cable. Try disconnecting the cable and testing each wire in it for continuity individually.

Another thing you may be suffering from is dirty dial contacts. Again, use a multimeter to check them when closed.

Your problem is nothing to do with lack of support for pulse dialling because you would still be able to call in to a pulse phone even if you couldn't dial out from it.

[andy1702]

I just looked at your photos again and it looks like green from your handset is going to T15 and green from your line cord to T2. If so that's the wrong way around. Line cord green should go to T15 (this isn't actually connected to anything, it's just a convenient place to put it) and handset curly cord green should go to T2.

I don't know for sure if this is the problem because it's difficult to tell where the green wires are actually going in the photo. Let us know how you get on.

Andy.

[twocvbloke]

I just looked at your photos again and it looks like green from your handset is going to T15 and green from your line cord to T2. If so that's the wrong way around. Line cord green should go to T15 (this isn't actually connected to anything, it's just a convenient place to put it) and handset curly cord green should go to T2.

I don't know for sure if this is the problem because it's difficult to tell where the green wires are actually going in the photo. Let us know how you get on.

Andy.

I've stared at them enough to see where the green wires are going, and they're connected to the right places, the two wires are also slightly different shades of green which makes it easier to follow...