Custom double neck steel guitar, EDS-1275 based circuitry help needed

[SUMIT SIMLAI]

Hello everyone,

I am new to the forum.

I must admit that I was referred through mylespaul.com to the link https://fretsnet.ning.com/forum/topics/doubleneck-wiring.

Have been playing the Hawaiian Steel Guitar since 1974. Only now I felt I should change my instrument so I got one made through a luthier in Kolkata India.

It's a double neck console style Hawaiian steel guitar, with each neck having two Seymour Duncan '59 Model humbuckers (B & N), one Seymour Duncan YJM Volume pot and one SD Tone pot. Two toggle switches have been incorporated and the circuit is designed around the Gibson EDS-1275 double neck model. All procurement decisions were taken in discussion with Seymour Duncan technical department and local luthiers. 

Short list of BOQ procured after long discussion with SD technical department:

1. Two of Seymour Duncan ‘59 Model Bridge Pickups
2. Two of Seymour Duncan ‘59 Model Neck Pickups
3. Two of Seymour Duncan YJM volume control pots 500K (logarithmic / audio taper)
4. Two of Seymour Duncan tone control pots 500K (linear)
5. One of Switchcraft 12010X switch - Long 3-way Neck selector switch
6. One of Switchcraft 12015X switch - 3-way Pickup Selector
7. One Switchcraft phono socket

It was only yesterday that I flew 1600 km from New Delhi to Kolkata to take delivery. Disaster struck when the guy told me he could not figure out the schematics and circuitry that I provided him, and therefore he couldn't get one of the toggle switches to work, while the other (the main one, 12015X) he could only configure for neck switching. 

As things stand now, no pickup switching, and God knows what else he's done, so the whole thing is a mess.

I have decided not to troubleshoot, rather to take apart the whole thing carefully and start afresh. For this purpose, I will need a fresh set of drawings, because the schematics I have (similar to the ones in that link above), do not provide connection details. Most confusing for me is the pickup selector switch configuration and I have no way to find out which is terminal 1, and which is what. A little help is sought to figure out these initial details.

I read the reply of Paul Young of May, 1 2013. Obviously, he seems to be an expert, while I am not. And the post is so old, I am not sure if he is still on this forum.

Any help in helping me figure out the terminals, the connectivity and the scheme will help complete the rewiring. Photos of the 12015X switch and the guitar are attached.

Also a switch setup diagram that I picked up along the way, is attached, not knowing if it is valid for my application.

Sumit Simlai

[Joshua Levin-Epstein]

I am confused. The Switchcraft switch you're showing has 9 terminals. The switch in the schematic has 12. 

the switch in the schematic is a 4 pole on-on-on switch. This might be pretty easy to get it to switch the necks following the schematic..

The switchcraft switch Gibson uses as a neck selector is not as "symmetrical". You should get a volt ohm meter and map out what connects to what in the various positions.

You could search the internet for that map, but a meter would be much faster.

[Joshua Levin-Epstein]

[Joshua Levin-Epstein]

OK, so maybe it wasn't that hard to find this. 

[SUMIT SIMLAI]

Well I guess the schematic from Gibson doesn’t show the unused terminals.

The schematic you enclosed, I have tha and it is not a circuit diagram.

But thanks anyway for responding.

[Joshua Levin-Epstein]

The schematic you posted uses a different switch. the 12015 switch is what Gibson used and probably still uses. You will need to put it into your schematic, replacing the switch that is there.

While I would rather have all the parts in front of me, here are my thoughts: Think of the letters (in the 12015 diagram) as the necks, the numbers being the pickups. The A1 and B1 outputs go to one set of controls, A2 and B2 to the other set. 

I can draw a complete diagram, but it would take time that I do not have. I suggest you study the circuit so you internalize how it works. Then you should draw your own diagram.  You can post that diagram here and I'll check it for accuracy. I'm pretty sure you have all the parts you need.

This wiring project is not for a novice. There are many ways to make a mistake. I know, I've made most of them. 

[Joshua Levin-Epstein]

pickup%20selector.pdfNeck%20selector_Pots.pdf    

Here are diagrams that, when combined, should show how to achieve the wiring you want. The 12015 switch is the complicated one, mostly because its size.

Comments: If you are not sure of the color coding for the pick-ups, go to the Duncan website. Once you've got this, the first hurdle is to have a place to ground the 4 pickups and the 12015  switch. I would mount the switch on a piece of copper shielding foil, solder all the grounds to it, then ground the foil to the output jack. I'm assuming the pickup selector is between the 2 necks. It might be mounted on a plastic plate which will be damaged if you cover the bottom with shielding foil and try to solder to it. Your next choice would be a piece of sheet brass. Next you connect the two outputs to the appropriate controls. You see there are 4 outputs from the switch, two "near" and 2 "far". I would tie the like outputs together at the switch so you only have two lines going to the controls. I am ambivalent about using shielded cable from the switch to the controls. If you decide to go with shielded, then ground one end at the switch and the other end to the case of the appropriate volume pot. I would ground the pots and neck selector switch directly to the output jack. Solder a wire to(far neck) volume control to tone control to neck selector to the jack. Then do the same, omitting the selector ground, for the near neck.

What can go wrong? Make sure you use the correct tab (ring) at the jack for grounding. Also, make sure the switches are oriented properly so they do what you expect. The neck selector should go perpendicular to the two necks. The pick up selector will be a compromise because the terminals are perpendicular to the throw of the switch.  So toward one neck will be the neck pick-ups, the other way will be bridge pickups. If you're installing the capacitors, use a heat sink between the leg being soldered and the cap to keep from frying the caps.

Like I sad, this is not a job for a novice. I'll be glad to be proved wrong. It won't be the first time.

Good luck!