G&L tech resources: Wiring harnesses

 
 

Here is a quick run-through of typical electronic components in wiring harnesses referenced in the other albums with possible substitutions as well as the availability in the G&L Online Store.

  1. The potentiometers made by the Chicago Telephone Supply (CTS) Corporation have been the standard in the industry ever since electric string instruments have been around, especially their 450G series. Sourcing from CTS is easily recognized by the serial number starting with “R137” on early pots or “CTS” stamped on the housing. In both cases, the pot can be dated by a “YYWW” formatted number, with “YY” the year and “WW” the week-of-year (01-53), either as part of the serial number, e.g. “R1377926” for a pot from the 26th week of 1979, or separately following “CTS”. Typical values one might encounter are 250kΩ Audio Taper, 500kΩ Audio Taper, and 1MΩ Reverse Audio Taper (for the bass cut in G&L’s PTB tone stack), both in solid and split shaft configurations. (Reverse) Audio Taper means these pots have an (anti-)logarithmic response, instead of linear, and hence act similar to the human ear. For a short period of time, just after BBE had taken over G&L in 1992, potentiometers were sourced from Japan. They do appear on instruments built mainly in the 1992-1993 time frame, tailing of in 1994 with outliers from as late as 1997, and are not further discussed. Similarly, around 2004 some pots were sourced by CGE, the supplier of Gibson, and between 2013 and 2015, some were sourced by Alpha Products, Inc., a Taiwanese company.

  2. Since 2011, National Semiconductor is owned by Texas Instruments (TI). They provide the LM4250CN programmable operational amplifier (op-amp) used whenever a preamp is included, basses as well as guitars from both eras, with the exception of the LF441CN Low Power JFET Input op-amp in the circuit for the BBE-era v1.0 preamp, notably used in the Climax Bass. An OEM LM4250CN replacement is available in the G&L Online Store.

  3. Switches have been used from a variety of sources, but 3 companies stand out. C&K with their 7000 Series Miniature Toggle Switches (datasheet), Tyco Electronics (TE Connection) with their ALCO Green Pushbutton and Toggle Switches (reference guide, dimensions, and datasheet), and Multicomp Miniature Toggle Switches (datasheet). Here are relevant examples:

  4. 1.The 3-position preamp switch on the (active) F-100E and L-2000E is an ALCO MTA206PA SP3T On-On-On mini-toggle. This switch has been discontinued by Tyco Electronics but hopefully this older datasheet will be of help finding a proper alternative or see point 6 (or 4) below.

  5. 2.For the 3-position “Splitter Switch” on the pre-BBE (active) F-100E and G-200, one needs a C&K 7411 4PDT On-On-On mini-toggle or equivalent. Since the “Splitter Switch” is nor longer implemented, no equivalent is available in the Online Store.

  6. 3.The 2-position “Splitter Switch” on the pre-BBE passive F-100 is a C&K 7401 4PDT On-On-On mini-toggle. Since this version of the F-100 has long since been discontinued, no equivalent is available in the Online Store.

  7. 4.The 3-position coil selector on the L-1000 is implemented using a (discontinued) ALCO MTA206PA, C&K 7211 DPDT On-On-On, or Multicomp 1MD6T1B5M1QE DPDT On-On-On switch. In the Online Store, one can get the Multicomp 1MD6T1B5M1QE.

  8. 5. Selecting a pickup on the (pre-BBE) Superhawk, L-series basses, ASAT Bass, El Toro, or Interceptor Bass is achieved by the use of the same DPDT On-On-On as above with the same replacements.

  9. 6.The 3-position preamp switch on the L-series basses, ASAT Bass, El Toro, or Interceptor Bass is implemented using the same DPDT On-On-On as above with the same replacements.

  10. 7.All 6 mini-toggle switches on the Comanche V are also of the above DPDT On-On-On type.

  11. 8.The series/parallel switch on the L-series basses, ASAT Bass, El Toro, or Interceptor Bass is implemented using either a C&K 7401 4PDT On-On, ALCO MTA406N 4PDT On-On, or Multicomp 1M41T1B5M1QE 4PDT On-On 2-way switch. The Multicomp 1M41T1B5M1QE is available in the Online Store.

  12. 9.The On/Off preamp switch on the Cavalier-E is an ALCO MTA106D SPDT On-On 2-position switch. The C&K 7101 SPDT On-On and Multicomp 1MS1T1B5M1QE SPDT On-On switches are equivalent to the ALCO MTA106D, which is available in the Online Store.

  13. 10.For each of the 3 separate pickup On/Off switches on the (pre-BBE) Invader or (3rd style) Interceptor HSS the same MTA106D, or equivalent, is used with similar availability in the store.

  14. 11.The expander switch on the S-500 and Comanche allows one to combine either bridge and neck pickup or all 3 together. G&L uses the same kind of SPDT switch as above, by any of the listed brands, with similar availability in the store.

  15. 12.Splitting the single humbucker on models like the BBE-era Invader and Legacy HB is achieved with the same SPDT switch as above with similar replacements.

  16. 13.The 2-position “Phase Switch”on the pre-BBE passive F-100 is an ALCO MTA306D 3PDT On-On mini-toggle. The C&K 7301 3PDT On-On and Multicomp 1M31T1B5M1QE 3PDT On-On switches are equivalent to the ALCO MTA306D, which is available in the Online Store.

  17. 14.To split the 2 humbuckers on models like the BBE-era ASAT Deluxe, ASAT Deluxe Semi-Hollow, Invader Plus, Invader XL, or Legacy 2HB, G&L uses the same kind of 3PDT switch as above, by any of the listed brands, with similar availability in the store.

  18. 15.For the series/parallel selector on the BBE-era L-1500, L-1505, and Climax Bass, G&L uses the same 3PDT switch as above, with similar availability in the store.

  19. 16.Finally, the preamp On/Off switch on the BBE-era L-1500, L-1505, and Climax Bass is also the same 3PDT item as above, with similar availability in the store.

  20. 17.When using a blade switch, most commonly a 3-position CRL/Centralab Lever Switch, (2-pickup models e.g. an ASAT with rear-loaded controls), or a 5-position CRL/Centralab Lever Switch (3-pickup models) is used. The Online Store carries 3-position and 5-position switches.

  21. 18.The ASAT JD-5 uses a 5-position Oak Grigsby Super Switch pickup selector.

  22. Several types of capacitors are used in wiring harnesses. On the volume potentiometer, one frequently finds a ceramic treble bleed capacitor, either 20pF, 100pF, or 200pF. Most commonly, the tolerance for this cap is ±10% (‘K’) but ±20% (‘M’) and +80%/-20% (‘Z’ or no letter) have also been observed. Others are polyester film capacitors, usually green, sometimes orange (so-call Orange Drop caps). These usually have higher values than the ceramic caps, ranging from 1,000pF to 100,000pF, if expressed using the power notation with pF as the base unit, is to .001µF to .100µF. Both notations are provided with µF in parenthesis. Their typical tolerance is ±10% (‘K’), especially in the first decade, and ±5% (‘J’) providing significance to only the 2 digits for the value in either notation. They typically are rated at 100V, although 300V has been observed too.

  23. Beyond the resistance of the potentiometers, additional resistors are often used for tone shaping. One particularly famous resistor, found on the tone control of a 2nd style SB-1 bass, pre-BBE Invader, (3rd style) Interceptor HSS, or the pre-1990 Broadcaster/ASAT, has a value of 6.8kΩ. Typical tolerance is either ±1% (brown band, rare), ±5% (gold, most common), or ±10% (silver).

 

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