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Old 15th Nov 2022, 1:44 pm   #1
Rob Hamptob
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Default Murphy B40 C

First time posting , I have dug out my Dads Murphy B40 C , complete except the mains lead , after a bit of searching found a plessey mk 4 , 3 pin plug , however found it wouldn't fit the B40 without the appropriate 3 pin socket .

Does any one know where I could find a connecting socket , would love to try and get it going , Rob
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Old 15th Nov 2022, 2:46 pm   #2
stevehertz
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Default Re: Murphy B40 C

Welcome Rob.

First things first, do you have the necessary electronics knowledge to tackle this? What level of electronics experience do you have? It's not the end of the world if you're wanting in this department, but we need to know so as to pitch any help at the right level.

For now, do not switch the set on (when you locate that lead), as things need to be checked first otherwise you may cause irreparable damage. That's unlikely, but quite possible. Best of luck.
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Old 15th Nov 2022, 3:02 pm   #3
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Default Re: Murphy B40 C

Welcome Rob to the forum. Loads of info on the web site and as stated do not just plug in
. There certain components that need checking/changing etc.
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Old 15th Nov 2022, 3:18 pm   #4
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Default Re: Murphy B40 C

Welcome Rob to the forum.

B40 what a heavy set. Had one many years ago when I could move it.

One question not asked of you is do you know the history of the radio?

When was your dad last using it, was it regularly in use, had any work been done on it by your father etc.

The reason for the caution is that capacitors in vintage radios can, and do go electrically leaky, as such when mains is applied and the HT is present within the set, these capacitors draw cuurent all the time, they can get hot and even cause damage to other components such as internal transformers and valves.

Good luck.

Adrian
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Old 16th Nov 2022, 8:57 am   #5
Rob Hamptob
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Default Re: Murphy B40 C

Thank you one and all for your replies ! . I certainly won't just switch on when I have located the part . It hasn't been used for 20 years , before that my Dad used it regularly . He was in the Navy and said if you can get it going I can certainly show you how to use it . A lot more research required I think , going to enjoy it ! , Thank you again , Rob
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Old 19th Nov 2022, 9:59 pm   #6
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Default Re: Murphy B40 C

Quote:
Originally Posted by Rob Hamptob View Post
First time posting , I have dug out my Dads Murphy B40 C , complete except the mains lead , after a bit of searching found a plessey mk 4 , 3 pin plug , however found it wouldn't fit the B40 without the appropriate 3 pin socket .

Does any one know where I could find a connecting socket , would love to try and get it going , Rob
I can probably help with the 3 pin plug you need, however to be sure, please post a photo of the socket on the receiver that you want to match.

Also bear in mind what everyone else has said about knowiing what you are doing ***before*** you switch it on. Not observing this could result in serious tears.......


Richard
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Old 19th Nov 2022, 10:06 pm   #7
M0FYA Andy
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Default Re: Murphy B40 C

'Socket on the receiver', i.e. a plug on the receiver end of the mains lead? Are you sure, that sounds somewhat dangerous!

Andy
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Old 19th Nov 2022, 10:16 pm   #8
trh01uk
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Default Re: Murphy B40 C

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Originally Posted by M0FYA Andy View Post
'Socket on the receiver', i.e. a plug on the receiver end of the mains lead? Are you sure, that sounds somewhat dangerous!

Andy
Andy,

its perfectly possible to have a female free plug (which is safe) and a male socket on the equipment......

Richard
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Old 19th Nov 2022, 10:23 pm   #9
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Default Re: Murphy B40 C

It's entirely possible that I'm misinterpreting here, but I get the impression that Rob has a mains lead with 3-pole Plessey Mk4 connector, but needs one that will mate with the 2-pole + shell earth Plessey Mk4 fitted as standard to the B40 PSU- though the latter may have been fitted with something else over its several decades.

Colin
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Old 19th Nov 2022, 11:26 pm   #10
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Default Re: Murphy B40 C

Colin,

yes, I can see we are all struggling to understand exactly what has been done here. Some photos will be essential to make progress with this one.

Richard
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Old 20th Nov 2022, 10:43 am   #11
Rob Hamptob
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Default Re: Murphy B40 C

What a fantastic forum/community, yes pictures coming soon. I'm looking out for a sturdy table at the moment, so I can get it at a decent height to work on in my Dad's conservatory, what a weight that thing is.

Because of the nature of my work I am very busy November and December but have plenty of spare time January and February, I have downloaded the manual and I do have electrical test equipment. However because this completely new to me my naivety will become apparent, apologies in advance, Rob
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Old 20th Nov 2022, 12:00 pm   #12
M0FYA Andy
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Default Re: Murphy B40 C

Richard,
Sorry, but 'female plug' and 'male socket' are oxymorons, resulting in ambiguity. My definitions of 'plug' and 'socket' come from an entire career in the aircraft industry, where confusion can be both costly and time-wasting (which of course is also costly), with connectors costing hundreds of pounds and many weeks lead time.

A plug has male contacts, and a socket has female contacts. Simple!

It doesn't matter whether the item is mounted on the end of a cable or chassis-mounted, this is a different attribute which must also be specified. So we can have a free (cable-mounted) plug or socket, and a fixed (chassis-mounted) plug or socket.
Of course there are odd-ball connectors which don't match this rule, such as hermaphrodite coax connectors, and others with a mix of male and female pins I have sen described as a 'plocket'!

But for straightforward connectors such as Plessey Mk4 the correct terminolgy is simple.

Andy
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Old 20th Nov 2022, 12:23 pm   #13
Andrew Sinclair
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Default Re: Murphy B40 C

The very first B40 series receivers had W connectors for the mains inputs, but all later sets from the B40A on-wards had a 2 pin Plessey Mk4 plug. The earth connection was a stud near the headphone sockets presumably to avoid earth loops!
Many have been modified to use a 3 pin Plessey Mk4. Others have a 3 pin miniature Bulgin circular connector as fitted to much Marconi instruments kit etc.
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Old 20th Nov 2022, 3:31 pm   #14
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Default Re: Murphy B40 C

Quote:
Originally Posted by M0FYA Andy View Post
Richard,
Sorry, but 'female plug' and 'male socket' are oxymorons, resulting in ambiguity. My definitions of 'plug' and 'socket' come from an entire career in the aircraft industry, where confusion can be both costly and time-wasting (which of course is also costly), with connectors costing hundreds of pounds and many weeks lead time.

A plug has male contacts, and a socket has female contacts. Simple!

It doesn't matter whether the item is mounted on the end of a cable or chassis-mounted, this is a different attribute which must also be specified. So we can have a free (cable-mounted) plug or socket, and a fixed (chassis-mounted) plug or socket.
Of course there are odd-ball connectors which don't match this rule, such as hermaphrodite coax connectors, and others with a mix of male and female pins I have sen described as a 'plocket'!

But for straightforward connectors such as Plessey Mk4 the correct terminolgy is simple.

Andy
Sure, I worked in an entirely different (commercial) industry where the free item was a plug (either male or female) and the fixed item was the socket (either male or female). I don't think there is any standard anywhere that defines which is right - or even preferred - its just different ways of doing things in two parts of industry that seldom come into contact with each other - except perhaps here in the vintage world!


Richard
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Old 20th Nov 2022, 3:36 pm   #15
stevehertz
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Default Re: Murphy B40 C

Quote:
Originally Posted by trh01uk View Post
Quote:
Originally Posted by M0FYA Andy View Post
Richard,
Sorry, but 'female plug' and 'male socket' are oxymorons, resulting in ambiguity. My definitions of 'plug' and 'socket' come from an entire career in the aircraft industry, where confusion can be both costly and time-wasting (which of course is also costly), with connectors costing hundreds of pounds and many weeks lead time.

A plug has male contacts, and a socket has female contacts. Simple!

It doesn't matter whether the item is mounted on the end of a cable or chassis-mounted, this is a different attribute which must also be specified. So we can have a free (cable-mounted) plug or socket, and a fixed (chassis-mounted) plug or socket.
Of course there are odd-ball connectors which don't match this rule, such as hermaphrodite coax connectors, and others with a mix of male and female pins I have sen described as a 'plocket'!

But for straightforward connectors such as Plessey Mk4 the correct terminolgy is simple.

Andy
Sure, I worked in an entirely different (commercial) industry where the free item was a plug (either male or female) and the fixed item was the socket (either male or female). I don't think there is any standard anywhere that defines which is right - or even preferred - its just different ways of doing things in two parts of industry that seldom come into contact with each other - except perhaps here in the vintage world!


Richard
If there is a hard and fast definition for this then I'd like to see it. I personally - and I may be quite wrong! - see things on the end of a cable as a plug, and something mounted on a chassis or housing as a socket.
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Old 20th Nov 2022, 5:39 pm   #16
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Default Re: Murphy B40 C

The bit with the male pins was called a plug in an early Bulgin catalogue.

The last Murphy B40D I owned was fitted with a 3 pin Bulgin chassis plug.

Photo of receiver as received.

Lawrence.
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Old 20th Nov 2022, 9:29 pm   #17
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Default Re: Murphy B40 C

Plug or socket on the mains cable. If a Plessey mk4, it can carefully be dismantled and the black insert containing the 3 contacts rotated to align correctly with the B40 one.
CHECK CAREFULLY THE RESULTING CONNECTIONS!
A bit fiddly, sometimes parts are reluctant to part, but it is possible with patience and care plus maybe a little elbow grease!
(another) Rob
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Old 20th Nov 2022, 10:15 pm   #18
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Default Re: Murphy B40 C

Quote:
If there is a hard and fast definition for this then I'd like to see it. I personally - and I may be quite wrong! - see things on the end of a cable as a plug, and something mounted on a chassis or housing as a socket.

In the army (and presumably followed as a standard in the other services): EMER Workshops F100 Section 123 paragraph 10:
"The insert is moulded to carry the contacts which may be pins, and the jnsert is then termed a PLUG. If the contacts are in tube form the insert is termed a SOCKET. A plug or socket insert may be fitted to either a free or fixed shell."


B40A to B40C receivers were always fitted with 2-pin fixed plugs for the mains supply in Navy service with a separate earth connection. A B40 with a 3-pin plug will have been modified in later life.

Last edited by 2000 type; 20th Nov 2022 at 10:26 pm.
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Old 20th Nov 2022, 10:40 pm   #19
M0FYA Andy
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Default Re: Murphy B40 C

Attached is a page from a document entitled 'Plugs and Sockets' issued by the Ministry of Aircraft Production in 1942.
Paragraphs 6a) and b) define a Plug and a Socket.

andy
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Old 22nd Nov 2022, 10:40 pm   #20
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Default Re: Murphy B40 C

Quote:
Originally Posted by stevehertz View Post

.......

If there is a hard and fast definition for this then I'd like to see it. I personally - and I may be quite wrong! - see things on the end of a cable as a plug, and something mounted on a chassis or housing as a socket.
So.... your mains extension leads have plugs on each end do they?
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