G&L tech resources: Wiring harnesses


The 1st style of the entry level basses, i.e. this 1983 SB-1 and 1982 SB-2, have the same wiring harness as the SC-1: a CTS 250kΩ Audio Taper potentiometer with a 20pF treble bleed capacitor as the volume control and CTS 250kΩ Audio Taper pot for the (treble cut) tone control. The latter has a 1,000pF (.001µF) cap from the signal lug directly to ground and is in series with a 47,000pF (.047µF) cap from the wiper to ground. The Basses by Leo website includes a block diagram supposedly for a 1st style SB-2. However, it is incorrect as can be verified from the description above and pictures below. Still, it is included here for convenience. The harnesses dramatically change for the 2nd style versions of both models. My 1985 2nd style SB-1 and 1990 SB-1 Deluxe no longer have a treble bleed cap on their CTS 250kΩ Audio Taper volume pot. The CTS 250kΩ Audio Taper tone pot has a 100,000pF (.1µF) treble bleed cap, soldered between the signal lug to the wiper, and is in series with a 6.8kΩ resistor to ground. A similar tone control is found on the pre-BBE Invader as well as the Broadcaster, all also introduced in 1985. A block diagram for the 2nd style SB-1 wiring harness can be found on the Basses by Leo site and is also shown below. The 2nd style SB-2, e.g. this 1990 SB-2 or 1991 SB-2 Deluxe, no longer has a pickup selector but rather a separate volume control for each pickup, using CTS 250kΩ Audio Taper pots void of any treble bleed caps. Note the Basses by Leo site also has sketches for the harnesses of the 2nd style SB-1 and SB-2. In 2015, the SB-2 also became generally available as the SB-2T with an additional master tone control on the control panel and the output jack moved to the side. As pictured below, on ‘Juicy Lucy’ this tone control is a smaller CGE 250kΩ Audio Taper pot in series with a 22,000pF (.022µF) cap to ground.