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3-conductor cord for 4-conductor use?

Started by WEBellSystemChristian, July 27, 2015, 04:05:47 PM

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WEBellSystemChristian

I was wondering if there was a way of wiring a 3-conductor cord as a 4-conductor? I have a 500-style Ivory cord on my 354, and I want to use it on my '56 Ivory 500. Problem is, it was built as a 3-conductor cord, with green, red, and white yellow conductors (instead of 2 white, red, and black conductors on a 500 cord). It even has 302-type strain reliefs, but still has the stubby boot that sticks out of the handset, which looks ridiculous! It fits well on my Ivory 500, so I was wondering if there was a way to make it work as a 4-conductor?
Christian Petterson

"Whether you think you can or think you can't, you're right" -Henry Ford

unbeldi

#1
Despite having four conductors in the standard 500-style handset cords, the sets can operate just fine with three conductors. One white and the red conductor are tied together on the R terminal on the network.  Therefore, you can eliminate one of them and instead tie one of the receiver contacts and one of the transmitter contacts together in the handset and use that as the common return that goes to the R terminal.  This is how the 300-series handset works.


G-Man

Sure, inside the handset connect one side of the transmitter and receiver to the red wire, the white wire to the other side of the receiver, and the green wire to the transmitter as shown on this diagram.

poplar1

I had to run a jumper inside the handset (to common the rec. and xmtr.) in late December at a friend's apt. in Rimouski, because one wire of the handset cord was open. Québec-Téléphone said it would be after the holidays before they could send anyone out to repair the company-owned phone.
"C'est pas une restauration, c'est une rénovation."--François Martin.

WEBellSystemChristian

I forgot that the 'white' conductor is actually yellow, just for the record.

What should I do if the yellow and red conductors are too short to travel the length of the handset? Should I have a jumper wire running from one of the transmitter contacts to the receiver?
Christian Petterson

"Whether you think you can or think you can't, you're right" -Henry Ford

unbeldi

Quote from: WEBellSystemChristian on July 27, 2015, 06:10:50 PM
I forgot that the 'white' conductor is actually yellow, just for the record.

What should I do if the yellow and red conductors are too short to travel the length of the handset? Should I have a jumper wire running from one of the transmitter contacts to the receiver?

Sure, that's the way it's done in the F1 handsets, remember?

andre_janew

I've done some experimenting lately on this subject.  It is possible to use a 3-conductor cord for 4-conductor use if you wire it as shown in these pictures.  It will actually work this way!  However, keep in mind that you don't have to use the same color wire that I did.

G-Man

Quote from: andre_janew on August 01, 2015, 07:05:42 PM
I've done some experimenting lately on this subject.  It is possible to use a 3-conductor cord for 4-conductor use if you wire it as shown in these pictures.  It will actually work this way!  However, keep in mind that you don't have to use the same color wire that I did.

Not only is it a very tidy job, but you showed me another way of neatly connecting with spade lugs on telephone cords.

For whatever reason I never thought of using a properly-sized Faston connector.

andre_janew

Yes, that one connector does slip over the existing spade terminal.  The original spade terminal remains in place.  With this setup, the 3-conductor cord can go back to being used in a 3-conductor handset.  There is no need to ruin a perfectly good 3-conductor cord just because you want to use it in place of a 4-conductor cord.

dsk

Surprisingly many telephones will accept a common wire for transmitter and receiver, even when they originally has a 4 wire cord.  I have solved problems with one broken wire in 4 conductor cords several times.

dsk