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Old 10th Oct 2010, 8:42 am   #1
twocvbloke
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Default BT Viscount 9511R causing no ringing on the line...

I have here a pair of BT Viscounts, a 9531R (speaker phone) in Beige and a 9511R in Red, and the latter one, which I would like to repair, is the one that caused a problem on my old phone line (this was about 3 or 4 years back). I pulled it out of a box recently and thought I'd set to repairing it, but, I haven't the foggiest where to begin...

The problem with the Red one is that when it was plugged into the line, it stopped the other phone on the same line from ringing, though it did ring itself, but was pretty unreliable, so I pulled it out of service and it sat in the box ever since. On initial inspection, the line cable has what looks like kinks inside the outer sheathing, within about a 14 inch length, and the plug looks corroded on a couple of the pins (also missing the locking tab, so would like to replace the whole thing), internally is fine, no obviously damaged or loose components, so I'm guessing the likely cause is a short in the cable. I haven't tested the cable with a multimeter yet, mainly cos I have no multimeter anymore, but I have the cable on my 9531R I could borrow...

And on another note, erm, which way round do the ringer and Recall connectors go? I didn't note them down when I stripped it recently for cleaning, and the 9531R is completely different internally so can't use that for reference. I did make a guess by looking at the traces on the back of the circuit board, and presumed that the ringer was controlled by the small IC, and the Recall being connected to the line traces, but I don't want to connect it to anything until I'm sure...

The main reason why I want this one working is cos it has some sentimental value, while not the original, the mother had one identical to this (might even still be in the house somewhere, in need of restoration), and the ringer is very comforting and soft, which I like, plus the handset cable is longer than on the 9531R making it less likely to be pulled off a table or shelf...

Thanks in advance...
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Old 10th Oct 2010, 12:12 pm   #2
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Default Re: BT Viscount 9511R causing no ringing on the line...

I had a brainwave, as I have no multimeter to test continuity, I found the next best thing, an LED and a battery, and after testing all the connections, the cable appears to have no shorts, but the lumps in the cable are still a concern...
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Old 10th Oct 2010, 4:23 pm   #3
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Default Re: BT Viscount 9511R causing no ringing on the line...

Hi,
I think that the recall in Viscount phones is controlled by a physical switch, as opposed to a transistor operated one, so your guess that the ringer is controlled by the IC may well be correct.
You could try tracing the print tracks on the phones PCB from the recall switch back to the line cord connection "plug" on the pcb.

Regarding your ringing fault, I have known Viscounts in the past to cause the symptoms that you are experiencing but do not know whether it has been caused by the line cord or a fault internal to the telephone itself.

If the latter, and you wish to keep the phone operational you could always disconnect the Blue of the line cord and use an external signalling device (a bit messy) or if there is enough space in side the telephone substitute the original signalling device with a proprietary one such as this or similar wired via a bridge rectifier, with the AC ends connected across the Blue and White of the line cord, and suitable current limiting resistor.

Regards
Andrew
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Old 11th Oct 2010, 2:53 am   #4
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Default Re: BT Viscount 9511R causing no ringing on the line...

Yeah, I've managed to trace the wires and PCB tracks, and the one I plugged the recall button into does short across two wires, which I presume makes an earth recall or something to that effect...

As for the main problem, the more I think about it, the more it actually sounds familiar, cos the mother's ex partner (formerly a late GPO/Early BT engineer) had a grey Viscount that was causing him line problems, so I guess it's a common fault. As for tracing the fault, if only I had a multimeter, I'd be testing every single component in there, cos I like the classic ringer tone that these phones make. Might have an excuse to go to maplins after all, got a few other components I need to buy for a couple of projects, aswell as a multimeter...

A more modern cable I pulled out of a box, in hopes of using it in this phone, only has two wires, Green and Red, unlike the Viscount's four wires, looking up the info on telephonesuk shows the red and green being B-Wire and Earth respectively. But upon testing them, the green wire is the A-wire, and this cable being off a BT Studio DECT cordless (retired, and misplaced!!!), have they lost their ways or something?

I can't wait to get myself a linesman phone, it'd make this testing so much easier, not to mention, a linesman phone can be fun to play with too...
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Old 11th Oct 2010, 6:01 am   #5
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Default Re: BT Viscount 9511R causing no ringing on the line...

Just been chatting with a friend over in the US, and he put me onto the idea of shorted diodes, and while I did check the 4x DC-rectifier diodes earlier, I missed the two that were on the Ringer line (D13 and D14), and they both allow power to flow both ways, I have a feeling that I have found the source of the fault. A little further probing with my LED & Battery continuity tester and of the three on the back of the dialling board, it seems that D16 and D17 are shorted too...

Being Zener diodes, they need to be replaced with other Zener diodes, but, if they're at fault, then they may be the cause of the failed phone...

D15 isn't at fault, but given it's age, I'm going to replace it anyway, all I need to do now is find some matching diodes to replace the duff ones. I've snipped them at one end to lift them up get the values, while leaving them in place to make sure I fit the replacements in the right place, and these are the ones this phone has:

ZPY 3.9 ITT - x3 (D13, D14 & D16)
BZX 85C 10 - x1 (D17)
BZX 79C 12 PH - x1 (D15)
(I have a feeling that the "ITT" on the first three is just the name of the maker, ITT)

And while I'm on it, the Capacitor "C4" looks like it's got a hot connection cos the board looks fairly toasty below it, but the cap itself looks okay (no bulging or leakage), but again, I need a multimeter to test it...

But, now I seem to be on the case, I'm feeling pretty pleased that I may have found the fault that besieges the Viscount series, can't wait to get the new diodes in...
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Old 11th Oct 2010, 8:56 am   #6
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Default Re: BT Viscount 9511R causing no ringing on the line...

I've found the latter two diodes on RS, Maplin were completely useless though, but I can't find the ZPY 3.9, a 1.3W Zener, the closest that RS has is a 5W Zener, the IN5335BRLG, but I have no idea if that would have an effect on the phone's workings...
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Old 11th Oct 2010, 8:41 pm   #7
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Default Re: BT Viscount 9511R causing no ringing on the line...

Quote:
Originally Posted by twocvbloke View Post
I've managed to trace the wires and PCB tracks, and the one I plugged the recall button into does short across two wires, which I presume makes an earth recall or something to that effect...
The recall button should do the following, Short the Red of the line cord (B Leg) to the Green of the line cord (Earth) and, depending on the position of any switching for either "Earth" or "Timed Break" Recall (you may find two of these underneath a plastic cover on the underside of the phone) open circuit the telephone loop between the Red and White of the line cord.

The two aforementioned switches, if fitted are for Recall type, as already mentioned, and Pulse or Tone dialling mode.


Quote:
Originally Posted by twocvbloke View Post
... looking up the info on telephonesuk shows the red and green being B-Wire and Earth respectively. But upon testing them, the green wire is the A-wire, and this cable being off a BT Studio DECT cordless (retired, and misplaced!!!), have they lost their ways or something? ....
There are many variations of line cord which follow "non - standard" colour coding. In the case of your Two wire cord, the wires are for the A and B legs of the line, so the wires have not lost their way as you suggest

Many modern phones, and in particular cordless models, use what is known as "two - wire" working where the ringing is not extracted via the Master Socket/line Jack capacitor and fed on an separate wire, as in the case of your viscount, but generated internally by either an internal capacitor in the equipment or electronic ringing detection which is then powered by the telephones base unit supply (in the case of cordless phones)

I am happy that you appear to have found the cause of the fault with your phone, and you are correct in thinking that ITT is the manufacturer of the diodes.

Regards
Andrew
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Old 12th Oct 2010, 5:08 am   #8
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Default Re: BT Viscount 9511R causing no ringing on the line...

Thanks, I just need to get the money together to buy a few bits and pieces, once the board money and the linesman phone (A TMC 1705, virtually identical to the GPO704 series from what I can see) I managed to snap up on Bay of e are paid for...

I've had a look at the Earth and Timed Break versions in the Viscount, and mine being the R version (Pulse-only) means there's only one socket for the recall button, but then, reading up on the use of the Earth connection means it's only needed for PBX/PABX use, but I might get myself a BT Revelation system to tinker with, even though I already have owned and sold one, but I didn't have the technical know-how to wire it and work it back then, I do now though, I probably used the wrong sockets (I just re-appropriated a couple of cable&wireless secondary sockets, which probably weren't suited to PABX use)...

I've been through every phone and modem cable I could find in this house (that isn't in use!!) and out of all of them, there was only one four-wire, and it uses non-standard colours, being Yellow-Green-Red-Black (in the correct order A-Earth-Bell-B), the only correct colour being green, I'll be using that cable in the red Viscount until I can find a nice long black 4-core cable (or another Viscount, whichever comes first!!!), but I'll be soldering it to the back of the line socket in the phone, saves splicing the existing plug & 4 wires onto the temporary replacement and then having to do it all again later...

Actually, while searching for phone cables, I came across a genuine BT Krone tool (logo'd and all), that'll certainly be very handy indeed once I find a master socket and a couple of slaves to tinker with.
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Old 12th Oct 2010, 8:15 pm   #9
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Default Re: BT Viscount 9511R causing no ringing on the line...

Hi,
If your Viscount is the Pulse only model, as you mention, it will almost certainly be wired for Earth Recall, which is indeed only used on PBXs.

A "cheat" for timed break recall, if required when there is no facility on the telephone itself, is to either quickly depress and release the switch hook (Flash) or, in the case of a Pulse dialling phone dialling the digit 1 should have the same effect.

The BT Revelation PBX requires standard master sockets on its ports, if you do manage to get hold of one of these PBX's I have one in regular use at home and know quite a bit (now) about programming them (make sure to get at least one system telephone with/for your system) so feel free to PM me when the time arrives.
Another advantage of the Revelation is that standard POTS telephones can be used as extensions, you only require the system phone for initial programming.

Andrew
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Old 13th Oct 2010, 7:20 am   #10
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Default Re: BT Viscount 9511R causing no ringing on the line...

It's amazing what you can learn in a few days, never realised that "1" on a Pulse-dial phone could act as a Recall button, I do now though!! Not to mention all the stuff I've read and been told about, once you know about things, it's actually quite simple really...

The Revelation system I had a few years back came with a couple of system phones and a few other random bits and pieces, but even with a printed off manual I couldn't figure it out, but after my phone socket hunting yesterday, I found one of the sockets I used on it (even had the 2-pair wire still attached), and it was most definitely a Secondary, no Capacitor, resistor or surge thingy, so that was probably one of the reasons why I couldn't work it out!!!

I have my eyes on a couple of Revelation systems on ebay, but I probably won't have the money after today (going to spend a bit of money at Maplin, could get the stuff cheaper elsewhere, but, of the stuff I want, it's all in one place there!), but we'll see...
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Old 14th Oct 2010, 10:42 am   #11
twocvbloke
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Default Re: BT Viscount 9511R causing no ringing on the line...

Well that's a bit of a number two, I just registered on the RS website, put my order together, and they demand I use a Credit Card, which I don't have, I only have a Visa Debit card...

Well, that's that plan off the cards...
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Old 14th Oct 2010, 7:08 pm   #12
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Default Re: BT Viscount 9511R causing no ringing on the line...

I seem to remember that this was a common problem on the Viscounts, when the handset was lifted to make or answer a call the switch-springs would loop the line and another set would loop out the bell circuit to stop bell tinkle on dialing (BTWD) as loop/dis signalling was still used a lot then.
Often, when the call was finished and the handset replaced the line loop would go (releasing the exchange) but the second switch springs would stick before the bell circuit loop should open again, thus not only causing BNR (bell not ringing) on the phone but all the extensions as well.
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Old 14th Oct 2010, 7:57 pm   #13
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Default Re: BT Viscount 9511R causing no ringing on the line...

They accept my Visa Debit card... You can phone them to make an order for non accepted cards too I believe.
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Old 15th Oct 2010, 10:41 am   #14
twocvbloke
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Default Re: BT Viscount 9511R causing no ringing on the line...

Well, I just tested the diodes again with a proper multimeter, and, well, it seems that the diodes I tested are working, cos with the meter they block it's test current when reversed, and allow it to flow when correctly polarised, that's annoying...

And I tested the hookswitch, and it releases the line and ringer as it should, so, I'm a bit stumped...

Got the temporary cable soldered in though, I've yet to plug it in and test though, maybe sitting in a box for 3 or 4 years fixed it...

As for accepting cards, it's odd, usually my card's accepted as a Visa, being Visa Debit (not Visa Electron though), but, it's not entirely essential, I'll work something out...
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Old 15th Oct 2010, 2:21 pm   #15
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Default Re: BT Viscount 9511R causing no ringing on the line...

oooookay, the Viscount is working fine, the other phones on the line work, and the viscount dials out perfectly, I don't get it....

Still, I'm happy that it's decided to work, and it's got a good cable fitted now, even if it doesn't match, so that's a change for the better...
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Old 15th Oct 2010, 6:46 pm   #16
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Default Re: BT Viscount 9511R causing no ringing on the line...

At least you got it working.
As well as the buttons on the keypad being a bit small and bouncy, I seem to remember that style of telephone being produced in a rather unpleasant salmon-brown colour, yuk!.
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Old 15th Oct 2010, 8:38 pm   #17
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Default Re: BT Viscount 9511R causing no ringing on the line...

Quote:
Originally Posted by MartinUKL View Post
At least you got it working.
As well as the buttons on the keypad being a bit small and bouncy, I seem to remember that style of telephone being produced in a rather unpleasant salmon-brown colour, yuk!.
Thanks, I'm not sure what I did, but I'm glad it's working, might place it on the unused socket on the landing, just to hear that lovely ringer tone...

The ones I like from the Viscount series are the red ones (with black cables), the Grey one, and the gareish green ones, if there was a blue one, I'd have that too...
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