P-T-P Posted October 29, 2008 Share Posted October 29, 2008 Just acquired a Sandberg California JM5 which a previous owner had set-up with passive electronics. I have the original 2-Band EQ which I believe is a Glockenklang made unit. I've asked Sandberg and Glockenklang for wiring diagrams but in the meantime, perhaps someone here could throw some light on things. The bass has a J and MM pickup fitted, the MM can run in either humbucking or split coil mode via a two way mini toggle switch, which is still fitted and working with the passive controls. The controls for the original set-up are Volume - Balance - Treble boost/cut - Bass boost/cut. The Volume is a push/pull active/passive type and, when in passive mode, the treble control acts as a traditional passive tone control would. The whole thing is powered by a 9v battery. Here's a pic of what I have... [attachment=15362:sandberg_eqq.jpg] The push/pull pot is the one on the left of this picture. It looks like when this lot were removed, the wires were all just clipped rather than de-soldered. On the reverse of the circuit board, there's a single red wire (battery?). Any suggestions as to what should connect where? Anyone with a Sandberg JM or PM care to open theirs up and draw up a rudimentary schematic? I'd be grateful for any assistance. Quote Link to comment Share on other sites More sharing options...
BigBadBassman Posted October 30, 2008 Share Posted October 30, 2008 Hi Pete, Just so happens I have California about my person with exactly the same circuit as yours Looking at your photo there are are 8 solder pads on the left hand side - the top 3 are the PUP inputs The top one (#1) is the positive from the neck (jazz) PUP #2 is the screen and negative from each PUP joined together #3 is the positive from the bridge and is white Still on the circuit board, the red or positive from the battery is soldered to the leg of the diode between the treble and bass pots - on mine the diode is soldered into the track on the top edge of the board and the leg is exposed below the body With me so far? The white wire on the volume pot circuit board is the output and should be soldered onto the tip terminal of the jack socket (the jack socket should be stereo and have 3 tags on it) The black wire is the earth which is soldered to a tag on the inside of the control cavity to earth the conductive paint to provide screening. A second black wire which is connected to the earth of the jack socket runs from this tag as does an earth for the bridge The switch on the bridge PUP should be OK as it is - all you need to do is make sure that the lead from the centre tags of the switch is soldered to an earth And finally you have to connect the black or negative wire from the battery is wired to the ring tag of the jack socket - this acts as a switch when you plug in a jack plug and turns the power on to the pre-amp Hope this makes sense. If you run into any problems give me shout and I'll PM you with my phone number Good Luck, Tim Quote Link to comment Share on other sites More sharing options...
P-T-P Posted October 30, 2008 Author Share Posted October 30, 2008 Hi Tim, Most excellent description and Sandberg have supplied a diagram which pretty much equates exactly to what you've said, nice one. Quote Link to comment Share on other sites More sharing options...
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