Early 1980s L-2000 circuits with 4-pin jack

Earlier on we had a thread running on the forum about early L-2000 circuits.  I was able to get a hand-drawn diagram from Paul Gagon at BBE/G&L that provided quite a few insights into what was going with this circuit.  There are also a few notes from Paul about the circuit.

This was followed up by forum member dch0719 who'd had to have his 1981 circuit rebuilt.  The technician who did the rebuild made a very nice schematic and diagram, and was kind enough to share them with the G&L community.

Click the thumbnails on the left for larger versions of the diagrams in JPG format.  Full-sized versions in PDF format that are suitable for high quality printing will be linked in the accompanying text.  Printing on photo paper using appropriate settings for your inkjet printer works really well.  Laser printer output on good quality plain paper should be excellent as well.

The jack used in this circuit is not a standard item available at the usual places or even most electronics shops.  Here are some links that may be helpful in sourcing the part:

I'd like to thank Paul Gagon of BBE/G&L for his help, technical insights, and support.


Old diagram thumbThis is an archive drawing of the circuit used in early 1980s L-2000 basses.  The actual author/artist is unknown but Paul states that it may have been done by George Fullerton, as he was doing most of the drawings at that time.  

Click the thumbnail for a larger version of the image.  A full-sized PDF is available here that can be used for high quality printing.  

Comments from Paul:
"The squiggly wires on the right side of the drawing are showing the mod G&L made to have both pickups work with the tone (Treble) control. You see, early on, only the neck pickup was connected to the tone (Treble) control. On the drawing you see the wires are already added to accomplish this mod and the wires that needed to be removed were squiggled(not sure this is a real word) over.
The left side of the drawing shows two resistors. The top one is a 100 Ohm (100r). This resistor is feed by the 9v Battery (through the output switching jack) and goes to the Preamp Board 9v input. The resistor on the bottom is a 1K Ohm (1000r). This resistor is feed by the output from the Preamp IC Chip and connects to the hot pin of the output jack. The purpose of these two additional resistors was to protect the IC Chip on the Preamp Board from pre-mature failure. The 100 Ohm resistor stopped excessive current from going into the voltage pin if the chip shorted out and the 1K Ohm resistor isolated the output pin of the IC from the output jacks "hot" pin."

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