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Wiring a Double-Female RJ12 RJ12 Telco Jack
Oops, this page doesn't have any of the photos in yet.  As soon as we've got them ready, we'll update this page. 
Step 3 - Preparing a Double-plug Female Throttle Jack

The steps for wiring a double-plug female throttle jack are the same as for a single-plug jack - except that there's some extra steps for wiring the second plug.  Using a sharp utility knife, carefully nick and strip about 8 inches of the outer plastic casing from a length of RJ12 flat cable that is about 18" - 24" long. 

It helps if you purchase double-female throttle jacks that have a built-in strain relief.  If you have such a plug, slide the cable under the slot for the strain relief. 

Wiring the First Plug
  • Using a BBQ lighter, melt 1" of the plastic coating off the white wire about 2" from the end.  Refer to the photo below.  Don't melt too much of the plastic!  It's best to use a salami approach. 
  • You've now exposed some very fragile wires.  Carefully twist the exposed copper strands on the white wire
  • Flux and tin the exposed wire so that you have a thick strand. 
  • While the white wire is very fragile, notice how melting the plastic, rather than using wire-strippers, has added back some of the stability. 
  • You've now converted some fragile wires into a more stable wire - but it's still fragile!
  • Twist the tinned white wire around the screw lug on the jack, making sure the white wire is aligned with the white spade terminal.  There should be a little slot in the plastic base where the white spade terminal slides under the screw.  The white wire slides into this same slot. 
  • Tighten down the screw, making sure the white wire slides into the same slot as the white spade terminal.  If you don't keep the white wire aligned, you'll slice the wire in two when you tighten the screw. 
  • Repeat the above process for the other 5 wires. 

Here's some photos of the above steps. 
Wire Threaded/Located
Inserted in Strain Relief
Melting the Plastic
Wire Exposed
Wire Tinned
Wire Under Screw

Wiring the Second Plug
  • Thread the white wire from the first plug to the second plug.  Always work the wire to the inside of the plug and not to the outside. 
  • Determine how long the wire should be stripped so it can be twisted around the screw for the white wire. 
  • Starting about 1" away from where you want to expose the copper wires, melt 1" of the plastic coating off the white wire.  Refer to the photo below.  Don't melt too much of the plastic!  It's best to use a salami approach - melt a little bit at a time. 
  • You've now exposed some very fragile wires.  Carefully twist the exposed copper strands on the white wire
  • Flux and tin the exposed wire so that you have a thick silver strand. 
  • While the white wire is very fragile, notice how melting the plastic, rather than using wire-strippers, has added back some of the stability. 
  • You've now converted some fragile wires into a more stable wire - but it's still fragile!
  • Twist the tinned white wire around the screw lug on the jack, making sure the white wire is aligned with the white spade terminal.  There should be a little slot in the plastic base where the white spade terminal slides under the screw.  The white wire slides into this same slot. 
  • Tighten down the screw, making sure the white wire slides into the same slot as the white spade terminal.  If you don't keep the white wire aligned, you'll slice the wire in two when you tighten the screw. 
  • You should have a short piece of wire that is outside of the screw.  Carefully trim this wire back flush with the screw as shown in the photos below.  Make sure you don't nick the wrong wire!
  • Repeat the above process for the other 5 wires. 
Cable Threaded
Melting the Plastic
Wire Exposed
Wire Tinned
Wire Under Screw
Wire Trimmed
  • Dab a bit of ACC under the slot for the strain relief so that the cable becomes an integral part of the plug. 

At this stage, we should have a single-plug and/or a double-plug female throttle jack that has about 12" - 18" of cable attached. 

We now have to install this assembly into the side of the module. 
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