Telecom 8100R (Ambassador) dial phone help wanted

[twocvbloke]

I guess that confirms it's not wired up like a 746 (even when one is converted) then... 

It's a shame there's no circuit diagrams available for these phones (at least, none that are online!), would make diagnosis a lot easier! 

I suppose we should rule out whether the ringer works or not, an easy way to test is to disconnect from the PCB, connect its two wires directly to a line cable (one wire to Blue (Bell), one wire to Red ("B")), basically wired up like a BT 50E bellset, and try calling from another extension, if the ringer rings, then it's not that, if it doesn't then something else is amiss (such as that microswitch or possibly a shorted coil).

If it does work, it could be the hookswitch, such as a bad contact inside or it is physically broken, but it could also be something in amongst the plethora of components in the corner there (though I can't see how as the ringer should only have access to switches to cut it in and out of the circuit)...

[andy1702]

I tried using a red and blue wire from a line cord and it didn't work. It also didn't work on a known good ringer and I tested the wires I used and they are all ok, so I had a look at a 746 wiring diagram and realised it's not the red and the blue wires I need to test the bell, it's the WHITE and the blue. So I hooked them up, dialled and it rings ok and that's going through the microswitch too.

So...
Bell is ok
Microswitch is ok

I can't find ANY visible fault so I now really do need a wiring diagram, or better still, a second working phone to compare it with. I still think the terminals should be exactly the same as a 8746 and certain terminals should be linked by jumpers. Has anybody else got one of these they could take the lid off and take a photo please?

[twocvbloke]

So, the ringer works, that's a good sign at least, but you are right, this does need a diagram, and having searched a number of times over the past few days, I finally seem to have found one via Sam Hallas' website (under "Guide Notes (Customer Apparatus)")!:

http://www.samhallas.co.uk/repository/po_info.htm

And to save time I was naughty and made a PDF "print" of just the basic 8000 series diagram to upload here:

[twocvbloke]

Just a quick addition, have you also tried a new line cable? Just incase the Bell wire is broken in the current one?

[andy1702]

I did a continuity test on the line cord and all the wires check out ok. It's interesting because it has the standard BT plug on both ends, with a socket in the bottom of the phone! The thing is at the phone end the connections in the plug are reversed (ie normal white, green, blue, red at one end but red, blue, green, white at the other) . So I also tried making up a new line cord with connections in the plug the same way round on both ends (ie white, green, blue, red) only to find it stopped the phone working even more, so I binned that idea and put the original reversed one back.

I'll have a study of that drawing and see if I can spot anything. This is by far the most difficult fault I've ever come across with a phone of any kind. I can see why they didn't catch on! 

[andy1702]

OK, is it just me or are there a lot of connections missing? Looks like there is a jumper of some kind missing between T4 and LP2 for a start.

[twocvbloke]

OK, is it just me or are there a lot of connections missing? Looks like there is a jumper of some kind missing between T4 and LP2 for a start.

LP1 and LP2 seem to be for indicator lamps of some kind, so unless your phone has such a feature, disregard it...

Looking on the diagram (my eyes are getting wobbly trying to do so!), the ringer wires are connected between T3 and T5, on your phone, it seems it's connected to T3 and T7, so, move the wire from T7 to T5 and see if that works...

It's interesting because it has the standard BT plug on both ends, with a socket in the bottom of the phone!

That's because BT wanted their own unique modular system to rival that of Western Electric's RJ10, 11 and 12 connectors, yet ironically, on reading about the Ambassador development, they used RJ11 connectors on the prototypes!! Kind of silly, but that's the GPO/BT for you...

[andy1702]

Looking on the diagram (my eyes are getting wobbly trying to do so!), the ringer wires are connected between T3 and T5, on your phone, it seems it's connected to T3 and T7, so, move the wire from T7 to T5 and see if that works...

Looks like you've cracked it!  I moved that bell wire from T7 to T5 and it works! turns out the problem was partly my fault because when I took the circuit board out of the phone I have to disconnect the bell wires. So most of the time I was looking for a fault that wasn't there because I'd disconnected it!

Anyway, for the sake of completeness and to help anyone else out who has a similar problem with one of these phones, here's a photo of the board wired CORRECTLY!

Thanks again for all the help.

[twocvbloke]

No problem, glad it's working again, it's amazing how one little wire can make a big difference... 

For posterity, it's usually a good idea to take a photo of connections before dismantling something, that way you have a reference to go back on if you get stuck, bit barn door I know, but, there you go...

[andy1702]

I think it was already in the wrong place anyway. It didn't work when i got it, which is why I took the top off in the first place. I normally follw the rule of 'if it ain't broke, don't mend it.' 

[twocvbloke]

I tend to be of the "even if it ain't broke, take it apart and have a look inside anyway" mentality, occasionally breaking things in the process... 

[Jim Stettler]

I normally follw the rule of 'if it ain't broke, don't mend it.' 

I tend to be of the "even if it ain't broke, take it apart and have a look inside anyway" mentality, occasionally breaking things in the process... 

I have been guilty of "Fix it till it breaks" before.
Jim S.

[twocvbloke]

Just this evening I've done the "take it apart anyway" thing with a new (to me) Lite-On PSU for my Lenovo M57 SFF PC (it serves as my IP Cam recorder and my Plex media server), just to check the new PSU was in good shape inside, with no swollen caps like the AC-Bel one it replaced has, just an instinctive habit, like an aussie on youtube says, "Don't turn it on, take it apaaaaart!"... 

[andy1702]

I think I do the opposite of that. Working on the theory of "if it ain't broke, don't mend it!" 

[Owain]

like an aussie on youtube says, "Don't turn it on, take it apaaaaart!"... 

"Big Clive" has a lot of teardown videos. He specialises in amazingly dodgy electrical things off ebay.