G&L tech resources: Wiring harnesses


With only a single Magnetic Field Design (MFD) bass humbucker, what would one expect for switching options? Still, with such a deceptively simple layout, Leo Fender was able to add a remarkable amount of sonic complexity. Shown below are a 1980 L-1000 and a 1983 L-1000F. A CTS 250kΩ Audio Taper potentiometer for the volume control is standard on these basses. The PTB tone stack consists of a CTS 250kΩ Audio Taper pot for the treble cut with a 50,000pF (.050µF) or 47,000pF (.047µF) capacitor from the wiper to ground (both values are equivalent within the ±10% tolerances) and a 1MΩ Reverse Audio Taper pot for the bass cut with a 2,200pF (.0022µF) treble bleed cap across the pot and a 1,000pF (.001µF) cap from the wiper lug straight to ground. The red tip coil selector is implemented with a ALCO MTA206PA On-On-On mini-toggle and hence offered 3 sonic options. Following the “L-1000” section of the “BASS INSTRUCTION SHEET FOR SWITCHES” shown below, “Towards the Nut Position - Is “Humbucking” mode” and the measured DC-R value for the MFD pickup on each bass is about 2kΩ in this setting. The “Middle Position - Is ”Single Coil” mode for normal playing” and the DC-R values measures to be about 4kΩ. Finally, “Towards the Bridge Position - Is “Single Coil” mode plus added bass boost” and corresponds with DC-R values of about 8kΩ. This bass boost is achieved by adding a 100,000pF (.1µF) capacitor, visible on the MTA206PA switch, grounding high frequencies, and is colloquially known as the “OMG” (“Oh My God”) setting. From the quoted DC-R values, assuming each coil of the bucker has a DC-R value of 4kΩ, the last setting corresponds with both coils being engaged in series, so not truly single-coil. This is confirmed in the block diagram drawn up by Paul Gagon, accessible here on the Basses by Leo website and shown below for convenience, where the “OMG” setting is labeled as “3 = SERIES HUMBUCKING W/.01UF CAPACITOR”. However, the 6.8kΩ resistor in the diagram cannot be found on either ‘Wunkay’ and is included in error. At some point, the Splitter switch was changed into a 2-position series/parallel switch as indicated by the pictured explanation for the “L-1000 BASS PICKUPS [sic] AND CONTROLS” from a much later date. When the L-1000 was reintroduced in the summer of 2018 as part of the CLF Research series of instruments, all 3 original sonic options became available again using a 3-position switch.