Author Topic: Modular Cord Question  (Read 2975 times)

Offline Kevin Lane

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Modular Cord Question
« on: May 04, 2011, 08:00:16 PM »
What are the active wires of a four-conductor modular cord?  I am taking a modular cord, cutting off one of the plugs, and fashioning a test line cord for a phone.

Thanks!

Kevin Lane

Offline HarrySmith

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Re: Modular Cord Question
« Reply #1 on: May 04, 2011, 08:10:31 PM »
Red and Green. Tip & Ring.
I did the same thing, attached two alligator clips and made a test cord.
Harry Smith
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Offline Kevin Lane

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Re: Modular Cord Question
« Reply #2 on: May 04, 2011, 08:12:42 PM »
Of course!  I never considered that they would be color-coded. 

Thanks!

Offline Adam

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Re: Modular Cord Question
« Reply #3 on: May 04, 2011, 08:46:52 PM »
In some modular cords, the conductors do not have any colors at all, since the cable is flat and not meant to be user-modified.

In an RJ-11 (the modular connector for a line cord) the TIP and RING are the two center contacts.

(Image stolen borrowed from the internet.)
Adam Forrest
Los Angeles Telephone - A proud part of the global C*Net System
C*Net 1-383-4820

Offline HarrySmith

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Re: Modular Cord Question
« Reply #4 on: May 04, 2011, 08:51:03 PM »
Good to know, thanks. Guess I picked the right cord with colors.
Harry Smith
ATCA 4434
TCI

"There is no try,
there is only
do or do not"

Offline Phonesrfun

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Re: Modular Cord Question
« Reply #5 on: May 04, 2011, 11:01:52 PM »
The second pair is sometimes used for other purposes, and in an ordinary 500 set, should not be connected anywhere, in my opinion.

Such other purposes are:

A second line connected at the jack in the house wiring
An AC lamp voltage for princess and trimline phones
A digital DC and multiplexed signal for digital PBX phones such as in Merlin, Panasonic and other PBX's that allow analog phones to be connected.

Connecting the black and yellow wires to either the red or green wires or connecting the black and yellow somewhere just to keep them from dangling can short out these other "purposes" and cause trouble. 

You can tape them off and let them dangle if you don't want to cut them off, or you can simply cut them off at the phone end.

Many new collectors don't know that it only takes two wires; the red and the green to make a phone operate.  They think (logically) that if the other two wires are there, they need to be connected, which is simply not true.  They are only there for the sake of the other things that can be done with modular connections.

Others have said that the yellow needs to be connected to the G post on the 425B network, but that is no longer the case.  It once was when the yellow wire in hard wired line cords was either grounded or bridged directly to the green wire.  Now, there are no more party lines so there are no longer ground connections in the modular jacks on the wall.

So, in short, just use the red and green pair, or if unmarked, the center most pair.

Knowing this, if you do just connect the black and yellow pair somewhere to keep them tied down and out of the way, 99% of the time, there will be no consequence, because in the house wiring in the wall that goes to the modular jack, you probably have nothing connected.  However, if you ever get a Panasonic PBX, or move, or sell the phone to someone that has some other configuration, it could cause trouble down the road.

All of this is my 2 cents.
-Bill G

Offline Ed D

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Re: Modular Cord Question
« Reply #6 on: May 04, 2011, 11:29:16 PM »
The second pair is sometimes used for other purposes, and in an ordinary 500 set, should not be connected anywhere, in my opinion.

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Offline Adam

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Re: Modular Cord Question
« Reply #7 on: May 04, 2011, 11:34:37 PM »
I agree with everything Bill said, except for me, the rule is "never cut".  Always tape and store.  You never know when you might need that extra conductor in the future.
Adam Forrest
Los Angeles Telephone - A proud part of the global C*Net System
C*Net 1-383-4820

Offline Jim S.

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Re: Modular Cord Question
« Reply #8 on: May 04, 2011, 11:40:45 PM »
You can use a surface mount block as an adaptor for your test cord. The test leads land on the screw terminals of the block, and you don't need to cut the cord.
JMO,
Jim

Use the same style of block on your hardwired phones, this makes a "reversable" mod adaptor
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Online stub

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Re: Modular Cord Question
« Reply #9 on: May 05, 2011, 11:41:40 AM »
Kevin Lane ,
                   I put red and green alligator clip lead ends on my cord with a 1mfd. 250 volt capacitor in series with the red line in for checking ringers.  One small green and red for the phone and a large red so I can remember where the cap is for checking ringers.   stub
Kenneth Stubblefield        
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   TCI

Offline dsk

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Re: Modular Cord Question
« Reply #10 on: May 05, 2011, 04:36:57 PM »
In some modular cords, the conductors do not have any colors at all, since the cable is flat and not meant to be user-modified.

In an RJ-11 (the modular connector for a line cord) the TIP and RING are the two center contacts.



I don't know why, but I have noticed a lot of telephones from the 80ies with line connected to red and yellow.
Quite frustrating when the telephone is dead with one cord, and alive with another.
I have an idea about this was an alternative standard to protect a market.
I have a cable with strap between yellow and green, this seems to work.

dsk

I have even got a regular New York number :-) 646 570 1796

Offline Phonesrfun

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Re: Modular Cord Question
« Reply #11 on: May 05, 2011, 05:00:36 PM »
Doesn't the European standard put pair 1 on different pins of the RJ-11 plug than the US standard?  I seem to remember seeing that here once.

-Bill G

Offline Adam

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Re: Modular Cord Question
« Reply #12 on: May 05, 2011, 05:10:56 PM »
Yes.  According to this page:

http://tinyurl.com/6y6g9aa

- in Greece, some of the RJ-11's are wired differently, with the outside live pair in a 4-conductor RJ-11 corresponding to the usual inside pair
- in Switzerland, the newer 6-pin plug can be configured to work different ways, and the standard-issue 6-pin plug to RJ-11 adapter often does not work, at least on the first few tries
- in France, I had better luck with a 2-conductor than with a full 4-conductor RJ-11 cable. Looking at the pinouts for a French phone connection, there are some non-standard wires, which a 2-conductor RJ-11 conveniently sidesteps.
Adam Forrest
Los Angeles Telephone - A proud part of the global C*Net System
C*Net 1-383-4820

Offline Owain

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Re: Modular Cord Question
« Reply #13 on: May 05, 2011, 06:16:25 PM »
Doesn't the European standard put pair 1 on different pins of the RJ-11 plug than the US standard?  I seem to remember seeing that here once.



Likewise in the UK.

Phones usually use the outer pair for A and B, because British phones use pins 2 and 5 pf the 6-pin UK connector.

Modems however could use the innner pair on the RJ11 and outer pair on the BT, with a cross-over cable.

Offline dsk

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Re: Modular Cord Question
« Reply #14 on: May 06, 2011, 01:52:36 AM »
Standardization is not easy.
A designer I know stated: (translated)" I do as I like, it will always be a standard which covers it"

In Norway all new telephone outlets are RJ45 (= Ethernet outlet)  The 2 center pins are used for telephone. The telephones uses US standard with RJ11 and center pair.

I have seen some Swedish telephones using the center pair as line, but  the next pair sends the line out again in on hook situation to make the next telephone in the system unable to listen. (I believe this 2. pair is used for power for light on e.g. princess phones in US)

Wikipedia has an article about pinouts, not complete, but good. http://tinyurl.com/35sb69 

It is important to be aware of: Telephones usually don't turn the contacts in each end, so colors will be reversed in the ends. (Important for some handsets) Data cables use to have equal pinout in each end.

dsk

I have even got a regular New York number :-) 646 570 1796