tucson Posted September 14, 2017 Report Share Posted September 14, 2017 I've completely restored a '72 Gibson SB-400 bass. I'm down to the wiring to finish it. It's got two single coil pickups, two slider switches on-off, one volume and one tone. I found a schematic wiring diagram at Gibsons' website but I really don't know how to read it. What I need is a pictorial where it's all drawn out so I can tell which lug on a pot, or which connections on the switch etc. Or if anybody knows how such a combo should wire together it would really help me out. I've tried several different ways but haven't found the one to make it work like it should. Thank you in advance for any help. Quote Link to comment Share on other sites More sharing options...
curtisa Posted September 14, 2017 Report Share Posted September 14, 2017 Try this: http://www.flyguitars.com/gibson/bass/SB_wiring_diagram.php Quote Link to comment Share on other sites More sharing options...
tucson Posted September 14, 2017 Author Report Share Posted September 14, 2017 Hey Curtisa, thanks for the reply! I found that website a couple of months ago. Actually that's the only way I knew it was a SB-400. Wired the way it shows there the tone knob makes no difference. The switches control the pickups correctly but if you turn on just one pickup, neck or bridge, it sounds pretty good. If you turn on both it only has about a quarter of the volume and it's real trebely. I don't think I mentioned before it's all brand new switches, pots and wire. I also just had the pickups rewound. I'm no luthier by any means but I've learned a lot on this guitar. I had to steam the fretboard off to fix a broken truss rod. I learned every pitfall involved in the refinishing process. It's really coming out nice though. I actually even played a gig with it already but I'm just trying to work out the details. I'm so close! Quote Link to comment Share on other sites More sharing options...
curtisa Posted September 15, 2017 Report Share Posted September 15, 2017 1 hour ago, tucson said: Wired the way it shows there the tone knob makes no difference. Check you have the bottom lug of the tone pot grounded to the case. 1 hour ago, tucson said: If you turn on both it only has about a quarter of the volume and it's real trebely One of the pickups is wired out of phase. Swap the two wires from either pickup on the associated switch. Quote Link to comment Share on other sites More sharing options...
curtisa Posted September 15, 2017 Report Share Posted September 15, 2017 Moved to the Tech Area -> Electronics Chat area for better housekeeping. Quote Link to comment Share on other sites More sharing options...
tucson Posted September 15, 2017 Author Report Share Posted September 15, 2017 Curtisa thank you sooo much! You nailed it. I swapped the pickup wires on one and that took care of that issue. I did have the bottom lug grounded but looking closer I could see a blob of solder had ran down and was real close to the middle lug. I addressed that and now it has tone adjustment. One little hitch is that the tone works like it should as you turn it down but when it gets to about 2 on the knob you can hear a little click and from 0 to 2 it has full treble. Any ideas? I can't thank you enough for your help! I'm so glad I posted here. For you to just read it and tell what was wrong is very impressive! Thank you! Quote Link to comment Share on other sites More sharing options...
curtisa Posted September 15, 2017 Report Share Posted September 15, 2017 18 minutes ago, tucson said: One little hitch is that the tone works like it should as you turn it down but when it gets to about 2 on the knob you can hear a little click and from 0 to 2 it has full treble. Any ideas? So you can wind it down from 10-2 and hear it gradually getting darker, and then from 2-0 it suddenly jumps up to full brightness instead of completely rolling down? I'd say the pot is faulty and would probably need replacing. Quote Link to comment Share on other sites More sharing options...
tucson Posted September 15, 2017 Author Report Share Posted September 15, 2017 Yes Curtisa that is exactly what it's doing, and when it gets to 2 there's a little click and it goes back to full treble. Not a physical click but an audible electronic click. I have some extra pots around here and I'll try swapping it out. Again, thank you so so much!++ Quote Link to comment Share on other sites More sharing options...
tucson Posted September 15, 2017 Author Report Share Posted September 15, 2017 Once again right on with your diagnosis. New pot fixed it. If you were close I'd buy you a beer but Australia is a long way from Bakersfield, California. I'll have to settle for telling you thank you, sincerely thank you! 1 Quote Link to comment Share on other sites More sharing options...
curtisa Posted September 15, 2017 Report Share Posted September 15, 2017 Glad to be of help. Quote Link to comment Share on other sites More sharing options...
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