Author Topic: GPO/BT "Jubilee" or "Compact" 776  (Read 12345 times)

Offline gpo706

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Re: GPO/BT "Jubilee" or "Compact" 776
« Reply #30 on: April 23, 2011, 06:35:26 PM »
Picked up the grey one today,

So after I had transformed the "ugly duckling" 706 into a black swan (more in due course), I started on this.

Now this has the original bellset and connecting curly cord, so was a bit more complicated than I first envisaged, you have two seperate circuit boards to contend with.

However, following Bob Freshwater's clear instructions on his site I rewired it as he described and bingo, another working set!

So clean-up time tommorow, it is pretty manky, and the grommet ends of the bell and handset are covered in dark brown / black goo, its either just dirt or maybe as someone here mentioned on another thread, a chemical reaction between the plastic in the bases and the grommets, these are moist and sticky, not just filth and dry like other sets I have cleaned - any ideas?
« Last Edit: April 23, 2011, 06:38:04 PM by gpo706 »
"now this should take five minutes, where's me screwdriver went now..?"

Offline gpo706

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Re: GPO/BT "Jubilee" or "Compact" 776
« Reply #31 on: April 28, 2011, 05:40:52 PM »
This is going in the "dunk tank" over the weekend, mixture of Oxy-clean and warm water and sunlight, wish me well folks!
"now this should take five minutes, where's me screwdriver went now..?"

Offline GG

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Re: GPO/BT "Jubilee" or "Compact" 776
« Reply #32 on: April 28, 2011, 10:39:27 PM »

Yo GPO-  The way to tell if the goo on the grommets is melted plastic, is to see if the plastic itself has become softened around that area.  The reaction I'm talking about won't cause the entirety of the grommet to be covered with crud, in fact the grommet itself will look fine: but the plastic it goes into will look melted as if from heat, and will be soft and pliable.  I'd like to find a cure for that, as it affects a lot of 706s with plastic baseplates. 

Meanwhile I've got a light gray one that's in darn good shape overall but just needs to go through the usual refurb process to come out like new (no fading though, so it just needs a scrub & buff), and have a ringer capacitor added in the bell unit, and the obligatory RJ-11 mod cord/plug for USA usage. 

Offline gpo706

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Re: GPO/BT "Jubilee" or "Compact" 776
« Reply #33 on: April 29, 2011, 08:47:08 PM »
The grommet and securing wall seem fine, so - no "sweaty" cords, it's getting dunked for the second time Sat night/ Sun morning.

Might even dunk the grommets.

Right took the base unit out and left the bell-set unit in the dunking tank in the daylight, the bugger keeps keeps going upside down.

So wedged a shelving "L" bracket into it to hold it in place, came back, and it still managed to go upside down.

So next I attach a "G" clamp to the underside to get the darn thing to sit up and that seems to have solved the problem.

This is by far the most annoying Peroxide dunking I have ever had.
« Last Edit: May 02, 2011, 05:03:53 PM by gpo706 »
"now this should take five minutes, where's me screwdriver went now..?"

Offline gpo706

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Re: GPO/BT "Jubilee" or "Compact" 776
« Reply #34 on: June 07, 2011, 07:05:55 PM »
The bellset cover has cooked nicely, it a uniform light grey now, the phone body I did dawn yesterday and left it in from 5am till sunset, its a bit lighter but not to match the bellset cover, must be a different plastic.

I was held back in my bleaching by the fact the original clear tub managed to crack down the front all over me when I was emptying the contents for the bellset, cue very wet phone bleacher.

Taken me weeks to find a replacement, but Sainsbury's had a "boot box" to the right dimensions.

The plastic at the back like the recesses for the carrying handle hasn't errr,  "seen the light" as such, so will get another dose facing the UV.

« Last Edit: June 07, 2011, 07:10:07 PM by gpo706 »
"now this should take five minutes, where's me screwdriver went now..?"

Offline Stephen Furley

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Re: GPO/BT "Jubilee" or "Compact" 776
« Reply #35 on: July 30, 2011, 10:32:13 AM »


Owain - Thanks!  The ringer is in the curved part of the wall base.  OK, so does anyone else here see the similarity in the overall design, or am I barking loony? 

GG, I have the wall mounting brackets for both the Compact Telephone and the 232.  It is possible, and least the original GPO literature says so, I've never actually tried it, to remove the ringer for the compact from its case, and fit it inside the wall bracket.

It is not possible to fit a ringer inside the wall bracket for the 232; there is nothing like enough space for one; You might just about get a modern miniature electronic one to fit, but not a full size bell one.  I've never used my 232 bracket, but I've just looked at it.  The deep part of the 'well' at the back is covered by a metal plate which was painted black, but is rusty on mine.  I've just removed that, and inside there is a six-way terminal block which fills most of the space.  At the back of the plate there is a notch which is presumable to take a short line cord down to this terminal block.  At the bottom of the bakelite there is a small hole to take cable, not cord, to the bellset which would be mounted on the wall as normal.  Close to the right-hand rear foot location there are two small screw holes which are countersunk at the top, so they are designed to fix something under the bracket, but I don't know what.  The GPO also supplied a separate Bakelite push button which could be connected to the 232 to provide earth recall on PABX systems, but I've never seen one of these.

There are some pictures of my 232 in the 'My Collection' thread which I started about 18 months ago.  I also have a dial blank and hand-cranked magneto, so I could set it up as a local battery model as well, at least cosmetically, I'm still looking for a battery box and a few other components to get it to actually work in this mode.  If you want some pictures of the bracket, and the 232 mounted on it I can take some for you.

Offline Stephen Furley

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Re: GPO/BT "Jubilee" or "Compact" 776
« Reply #36 on: July 30, 2011, 03:28:15 PM »
These are just simply beautiful sets. I'd love to get a matching set. Are they fairly common or is this a big investment set. Really quite cool looking....Doug

Not too epensive but you will have to keep an eye out if you want the colour matching bellset.

(Ebay) Brown Compact without bellset, in Brown - starting at 5 + postage

(Ebay) Two Compacts in grey with base units (they have sun yellowed) - starting at 30 + postage.

(Ebay) Blue Compact without bellset - Buy It Now 27 + postage


Owain,

That blue Compact is the colour that I have.  I had the choice of that with wall bracket, or the Jubilee one without, and in slightly less good condition.  Both were the same price, but I can't remember how much now.

There is nothing technologically innovative about the 776, unlike the Trimphone for example.  It's basically just the standard 746 split into two parts, and mounted in separate boxes.  I have the GPO documentation for their engineers somewhere, but I can't find it at the moment.  This was before the standard BT plug-in system, and there ware several installation options.

The bellset in its light grey case could be wall mounted via a metal plate, with cable connected to the line and a special coiled line cord fitted with square 706/746 style grommets at each end then connected from there to the 776.  This was the most common method.

Where the bellset needed to be mounted  at a greater distance from the telephone the line could be connected to the bellset by cable, as before, and another cable run to a standard GPO Block Terminal (small junction box) wall mounted close to the required telephone location, from where the 776 would be connected by the special line cord, as above.

Where the telephone was to be mounted on the wall bracket it could use either of the above methods, or the ringer could be removed from its case and installed in the lower section of the wall bracket, under a colour matched plastic cover.  Cable was run to the ringer, and the special line cord from there to the telephone, so that it could be picked up from the bracket and carried around within the reach of the cord if required.

When I bought my 776 it had been irreversibly modified for use on the now-standard BT plug system.  The special line cord had been replaced by a Trimphone one with a standard BT plug.  A few links had been moved around and the bellset had been fitted with a short, about 30cm long, modern grey linecord, also fitted with a BT plug.  A 2-way adapter was supplied with it to enable both to be plugged into a single socket.

The 776 could be fitted with a switch, and button, for earth recall with a PABX, but I doubt if many ever were; this wasn't really a business 'phone.  The button took the form of a flat tab at the bottom of the 'phone, towards one side, and a dummy tab would be mounted on the other side.  I don't think there was an option for two switches.

There were three versions, an early one, then the Silver Jubilee, and then the standard ones.  I think each had a different model number, and there were slight internal differences.  All were dial instruments; there was no button version, either LD or DTMF.  It used standard transmitter and receiver elements, as on the 746, but I think it the red electronic transmitter rather than the black carbon one.  The red transmitter was made as a direct replacement for the black one in 706 and 746 sets, and was fitted from new in some of the later ones.  Inside its case the ringer was also a standard one.  If I remember correctly the dial was a slightly modified one, being fitted with a weaker spring so that it could be dialled with one hand without sliding about on the table, due to its much reduced weight compared to a standard telephone.

It's a nice telephone, but they were only made for a fairly short time, and were not very popular.  They were significantly more expensive than a standard 746 telephone, and at the time the 'works' were becoming quite dated, being basically the 746 design, from 1967.
« Last Edit: July 30, 2011, 03:42:38 PM by Stephen Furley »

Offline Owain

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Re: GPO/BT "Jubilee" or "Compact" 776
« Reply #37 on: July 30, 2011, 04:11:56 PM »

The 776 could be fitted with a switch, and button, for earth recall with a PABX, but I doubt if many ever were; this wasn't really a business 'phone.  The button took the form of a flat tab at the bottom of the 'phone, towards one side, and a dummy tab would be mounted on the other side.  I don't think there was an option for two switches.


At that time, however, party lines were still quite common, which required a recall switch to obtain the exchange line and set up the metering for that subscriber .

Offline Stephen Furley

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Re: GPO/BT "Jubilee" or "Compact" 776
« Reply #38 on: July 30, 2011, 04:52:00 PM »
I think, but I'm not certain, that the GPO documentation specifically excluded shared service lines (party lines) from the possible installations for the Compact Telephone.  The 706 was available for shared service, but I'm not sure if the 746 was.  I know that several options, local battery magneto signalling mode for example, which were available on the 706 were dropped when the 746 was introduced.  I've got a Mk.1 706 which I converted to magneto mode and I chose that model because it was more difficult on the Mk. 2, and not an option on the 746.  If shared service was still offered on the 746 then I can't see why it shouldn't have been on the Compact, since they're almost the same 'phone.

I've seen the document fairly recently, but I can't remember where.  I's probably in a box either in the cellar, or in my storage unit down in Purley.  When I get time I'll try to find it.

Paul's top picture of the silver Jubilee seems to show the switch and dummy tab fitted; I've never actually seen one which has them.

The Trimphone could also take a switch, though again I'd never seen one which had this fitted.  A couple of years ago one of the switch assemblies turned up on Ebay, so I bought it and fitted to one of my Trimphones.  I used it on my desk at work until we moved into an office with no analogue telephone service; we're gradually moving to IP.
« Last Edit: July 30, 2011, 05:08:20 PM by Stephen Furley »

Offline Owain

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Re: GPO/BT "Jubilee" or "Compact" 776
« Reply #39 on: July 30, 2011, 05:33:29 PM »
I think, but I'm not certain, that the GPO documentation specifically excluded shared service lines (party lines) from the possible installations for the Compact Telephone.  ...

The Trimphone could also take a switch, though again I'd never seen one which had this fitted. 

Compact Phone:
Dgm N 876 - Connections for Exclusive Service, Shared Service, PBX Extension and details of add-on units.
Dgm N 2801 - Connections for Plan 1A, Exclusive Service.
Dgm N 2821 - Connections for Plan 1A, Shared Service.
Dgm N 2804 - Connections for Plan 4 Exclusive Service.
Dgm N 2824 - Connections for Plan 4 Shared Service.

There was a restriction on mixing Compacts and 706/746 on a Plan 4.
http://www.britishtelephones.com/t776.htm

I had a Trimphone with a switch in 1979, because we had a party line.

Offline Stephen Furley

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Re: GPO/BT "Jubilee" or "Compact" 776
« Reply #40 on: July 30, 2011, 05:57:35 PM »
Thank you Owain, I stand corrected.

We were on shared service with a 300 series until about 1966-67 when it was replaced by a grey 706 on an exclusive line.  I hadn't realised that it was still being used for so long after we came off it.  Which was the plan which had extension 'phones on the old style plug-in system?  Was the Compact available on that?

Offline Owain

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Re: GPO/BT "Jubilee" or "Compact" 776
« Reply #41 on: July 30, 2011, 06:34:18 PM »
Thank you Owain, I stand corrected.

We were on shared service with a 300 series until about 1966-67 when it was replaced by a grey 706 on an exclusive line.  I hadn't realised that it was still being used for so long after we came off it.  Which was the plan which had extension 'phones on the old style plug-in system?  Was the Compact available on that?

Plan 4 was the old style plugs. It could be combined with Plan 1a for hardwired phones.
http://www.britishtelephones.com/extnplan.htm#plan1a

Offline Owain

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Re: GPO/BT "Jubilee" or "Compact" 776
« Reply #42 on: July 30, 2011, 06:46:45 PM »
I know that several options, local battery magneto signalling mode for example, which were available on the 706 were dropped when the 746 was introduced.  I've got a Mk.1 706 which I converted to magneto mode and I chose that model because it was more difficult on the Mk. 2, and not an option on the 746. 

Adapters, Local-battery, No. 5 and No. 6, could be fitted to Tele 706.

Adaptors local battery cannot be fitted to Telephones 746.

Adaptor, Local-battery, No. 4 can be fitted to Tele 710.

Offline Stephen Furley

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Re: GPO/BT "Jubilee" or "Compact" 776
« Reply #43 on: July 31, 2011, 12:10:44 PM »

There is a similarity in design. Note the difference between a bell and a bellset though; the bellset also has the induction coil and other components.

There's a higher resolution image of a 232 on a 200 wall bracket here. " This phone did not come with bells and requires a bellset N0 1 or N0 26. Phone can be taken off the base and is not fixed. Four cups fit the four rubber feet on the base of the phone." It sounds like the bellset wasn't concealed in the plastic curved wall bracket but I could be wrong - there doesn't look like there's enough space.

Owain,  The GPO seem to have been slightly inconsistant with their use of terminolgy.  Something which contained both the capacitor and induction coil in addition to the bell, e.g. the No. 1 and 25 as used with the 150 and the 162, always seems to have been referred to as a bellset, or bell set; I've seen it both ways, but one word seems to have been more common.

Something which contained the capacitor, but not the induction coil, e.g. the No. 26 as used with the 232, was still referred to as a bellset.

Something which contained neither the capacitor nor the induction coil was referred to as a bell.

The small grey box for use with the 776 Compact Telephone as designed and built contains the capacitor in addition to the ringer and gongs, though the one in mine was disconnected as part of the conversion before I got it.  It's basically a smaller, modernised version of the bellset No. 26, and so following the above convention should have been called a bellset, but it wasn't, though most people still seem to call it one.  In both N876, and the introductory document for engineers it's referred to as a Bell Unit, and the device itself is stamped 'BU 776'.  Was this term ever used for any of the older versions?

To save space the capacitor is mounted under the 'B' gong.  Sorry, the picture is terrible, I don't have a digital camera, and the one in my 'phone is useless for close-ups.  It's a nice little unit; pity they weren't available separately for use with older 'phones.

Re. the wall mount for the 232, while there is not room to mount a conventional ringer inside it, I did wonder if a 232 with bellset No. 26 mounted under it would fit on the bracket.  It Won't, there's not enough room at the back for it to fit.
« Last Edit: July 31, 2011, 12:39:54 PM by Stephen Furley »

Offline Stephen Furley

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Re: GPO/BT "Jubilee" or "Compact" 776
« Reply #44 on: July 31, 2011, 12:49:28 PM »
I know that several options, local battery magneto signalling mode for example, which were available on the 706 were dropped when the 746 was introduced.  I've got a Mk.1 706 which I converted to magneto mode and I chose that model because it was more difficult on the Mk. 2, and not an option on the 746. 

Adapters, Local-battery, No. 5 and No. 6, could be fitted to Tele 706.

Adaptors local battery cannot be fitted to Telephones 746.

Adaptor, Local-battery, No. 4 can be fitted to Tele 710.

Yes, it was the No. 5 which I needed.  I think the No. 6 had extra switch contacts, but I'm not sure what they were for.  I've never managed to find another one for the second 'phone.  I have got one of the sets of additional switch contacts somewhere; I wonder if I could use that, and wind  a small coil to make my own Adapter, local battery?  The one Which I finished converting works fine with an old local battery 'phone on the other end of the line.  It can be used for neighbour's children to amuse themselves with, until the almost constant ringing drives you round the bend.