Soldering a Socapex Plug to a Multi-Cable

I wrote earlier about the upgrade of the lighting distribution system for Pote theatre as part of the recent lighting upgrade that included scrapping our 48-dimmers and 48-dimmer/242-circuit patch bay.  A major portion of that initiative was to replace the de-rated 3-prong pin-out twistlock sockets with 3-pin stage plugs (which are arguably the de-facto standard in the U.S. for single-circuit lighting distribution.)

In the process, we replaced the dedicated lighting battens and the associated circuit raceways, with drop-cables from the grid via multi-circuit cables, terminating in 6-circuit breakout “splays”.  The “splays” attach to the multi-cable via a Socapex connector.  The cables are managed in a sort of old school manner with manual dead-hung spot lines attached to Kellum grips partway down each cable.

Image of Burned Multi-Cable

Damaged multi-cable burned while resting against a Q-lite

We had a learning experience several weeks ago when after circuiting and “ringing out” one of the battens on stage, the electricians lifted the electric out to trim, but did not make the effort to take the journey to the grid required to lift the multi out high enough to clear the batten.  The unfortunate result of this oversight was that the multi rested against one of the Q-lites that we use as worklights.  Even lamped at 500 watts these fixtures get very hot, hot enough to melt the multi-cable when it rested against the fixture for long enough.

The repair of this incident required the replacement of a 70’ length of multi-cable.  Once again, my friend Jerry Onik of Heartland Stage of Omaha supplied me with the necessary length of cable.  He suggested that I re-use the Socapex connector.   While I have been familiar with the Socapex connector as a user, I had never had the need or opportunity to work on one, so I was cautiously optimistic that I could  perform the task.

My first challenge was figuring out how to take the connector apart.  I was thwarted in my first attempt to break it open.   After a nearly useless web search, a couple of emails (one to the Stagecraft Mailing list) and some experimentation I found the following steps necessary to remove the plug:

  • Attach the male plug from one of the splays to the female that you want to remove.
  • Grip the body of the male and the female firmly.  (I used pipe wrenches but rubber-jawed arc-joint pliers would probably be preferable)
  • Turn the body of the Male plug CLOCKWISE (which is the opposite of the direction that you would expect) to unscrew the body of the male plug from the terminal end.
  • Turn this outer body until it unthreads from the contact holder core.
Image of the removal of the original leads from the Socapex connector

Removing the original leads from the original Socapex connector with a 25 watt soldering iron. Note the color-coded wires from the original installation.

Removing the contacts from each of the 14 conductors was pretty simple.  The 25 watt soldering iron that I use for repairing microphone cable was just sufficient to the task of heating the solder in each of the solder cups to the melting point.

Image of "Tinning" one of the new leads.

"Tinning" one of the new leads with the 40 watt soldering iron in preparation for soldering it to the re-used Socapex connector

However, when it came to attaching the old connector to the new leads, I ran into problems.  The little 25-watt iron just couldn’t bring the 12-gauge wire to an adequate temperature to “silver” the leads, not to mention heating the wire the solder and the solder cup to the

Image of lead being soldered to Socapex connector

Soldering the last lead (#12) to the Socapex connector. Note the white number-labeled leads from the new multi-cable. Also note the unshrunk shrink-tube insulation

temperature necessary to create an adequate electro-mechanical connection.  After some further experimentation, I found a 40-watt version of a soldering iron that was barely adequate to the task.  Even so, the tedious process took about 3 hours of soldering altogether (spread over 3 sessions).  Following are a few things to consider when doing so:

  • Make sure that the shell of the connector shell is installed on the cable before beginning to solder leads to the contacts.
  • Slide the shrink-tube over the lead before soldering each lead to the contact and prevent shrink-tube from receiving too much heat from the soldering process so that it will slide over the solder cup and bared lead to insulate the lead from a possible short-circuit with a neighboring lead or the connector shell.
  • Take pains to connect the correct leads to the correct contacts.  Each contact has a certain function (see the next two points)
  • Begin by soldering the 2 ground leads from the multi-cable to pins 17 & 18 and connect pins 13 through 18 by connecting them with a ring of solder.
  • Solder the outer ring of contacts as follows:
    • Pin  1-Circuit 1 Live (Hot)
    • Pin  2-Circuit 1 Neutral
    • Pin  3- Circuit 2 Live (Hot)
    • Pin  4-Circuit 2 Neutral
    • Pin  5-Circuit 3 Live (Hot)
    • Pin  6-Circuit 3 Neutral
    • Pin  7-Circuit 4 Live (Hot)
    • Pin  8-Circuit 4 Neutral
    • Pin  9-Circuit 5 Live (Hot)
    • Pin 10-Circuit 5 Neutral
    • Pin 11-Circuit 6 Live (Hot)
    • Pin 12-Circuit 6 Neutral

Once I completed the soldering, I heat-shrinked the shrink-tube insulation and closed the connector up by reversing the process used to dismantle it in the first place.  Before making up the electro-mechanical connections in the junction box on the grid, I  tested each circuit for continuity with the other end of itself.  I also tested for continuity between each pin and all of its neighbors. identifying continuity would have contraindicated completing the re-installation until it had been removed since that would have indicated a later short-circuit and probable damage to the connected dimmers.

After completing the connection I “rang out” each circuit by connecting each one to a fixture and bringing up the associated dimmer on the Unison touch-pad. Fortunately, all circuits functioned properly.

That’s all for now.

Have fun.  But be safe!

SJM

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One Response to “Soldering a Socapex Plug to a Multi-Cable”

  1. Very helpful. I’m in the same fight now as you were.. trying to find a resource on repairing a cable that’s been melted.. My melt point is near enough to the end so my 100′ socca will now be about 96′ (unless I really mess up.)

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