1950's Gibson Electricals

Catalog of Electrical Components As Used By Gibson in the 1950s and 1960s
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This page shows some of the various interesting things about a few of the major pieces of the Gibson wiring harnesses of the 1950s and into the 1960s.
Part of my work as Dr. Vintage is renewing and reconditioning these great old vintage wiring harnesses. I do this for well-known vintage parts dealers and individual owners alike. Doing this work has seen hundreds of old Centralab and IRC pots, Grey Tiger and Sprague caps, and Switchcraft switches galore pass through my hands. I've seen enough to have a good eye for when something is different or unusual. I've attempted to capture some of the interesting variances of these parts.
This page is a living document. I will be adding pictures and information as I learn it. Check back often!

Switchcraft 3-way Toggle Switches
While the function of the Switchcraft 3-way switches didn't change (except for the three-pickup Les Paul Customs of the late 1950s), certain details changed between the 50s and the later versions. Here are some pictures to show some of the differences.
The switches used through most of the 1950s had no lettering on them that identified them as Switchcraft brand switches. That changed in the very-late 1950s (as best I can tell), if not into 1960.

But what if the switch is still installed in the guitar? How can you tell if the switch is a proper 50s switch? There are a couple of quick "tells" that identify the 50s-generation switches from the back. One of the differences is the order that the electrical 'leaves' are assembled, and another is the direction the stack screws pass through the stack. Here's a picture of the early-style switch to show what a proper 50s switch looks like from the back:

Now compare that one to the later style switch:

An interesting thing that varied with no real pattern is how they accomplished the "both pickups on" function of the middle switch position. There's a simple way, and a complicated way, and they both produced the same result with the same switch.
The simple way was to join the two upper terminals together and connect the lead to the output jack to that junction. That method did get used back as far as the earliest Les Pauls (I recently handled an 'orange wire' '52 harness that was wired that way), and appeared throughout the 1950s. But despite its simplicity, it wasn't the only method found in the 1950s.
The more complicated method was to run the pickup leads to different terminals than you see in the 'simple method' and then run an extra piece of wire across the back of the switch in the form of a jumper to accomplish the "both pickups on" function in the middle switch position. This was used at least as often in the 1950s as the 'simple' method.
Why were two different methods used? There's no way to know for sure. I personally believe that the wiring method varied with whomever was assigned to the soldering station at the Gibson plant on any given day. Just my opinion, of course. Here's a picture showing both ways:

This illustration shows how the two different wiring schemes actually hook up to the switch.

This picture shows the central ground for the entire electrical circuit in a Les Paul. The volume and tone controls ground through the braid shield on each lead.

IRC Pots
IRC pots were the ones used in the earliest Les Pauls. Starting in the approximately 1953s, Gibson started using Centralab pots concurrently with the IRC pots.
The latest IRC pots I've seen in Gibson use was up to very-late 1955. In a couple of cases, I've had a wiring harness that used both brands simultaneously. For example, I recently had a completely-original very-early 1956 Les Paul Junior harness that had a very-late 1955 IRC volume pot and a very-early 1956 Centralab tone pot, with a Grey Tiger tone cap. (If anyone has evidence of later IRC pots, please forward that information to me!)
IRC pots changed little during their use in the 1950s. The major notable changes were to migrate from a solid shaft to a split shaft (as did the Centralabs), and a slight change to some of the coding stamped into the back cover. The following pictures will show some of the variations.

This picture shows the overlap of the two brands as late as 1955

Centralab Pots
As early as 1953, Gibson started using Centralab pots concurrently with IRC pots.
As with many of the hard-parts that Gibson used in the '50s, features of the Centralab pots changed over the years. The following pictures will show some of the variations.

Tone Capacitors Over The Years
This section will eventually show the various tone caps that Gibson commonly used over the '50s. At the moment, it's incomplete. Some of the ES3x5 model guitars of the late 1950s and into the 1960s used ceramic disc tone caps, which I find entirely boring to talk about or photograph, so they'll be excluded.