Having Just wired up my project Jazzmaster and having done some checking to fix the wiring.....I can now say with some confidence that both the SD and Fender wiring diagrams are incomplete and have some errors. So, if you are replacing pots on your guitar or especially if you are building a reproduction for yourself look out it won't work if you use these sources as reference.
The Jag diagrams also seem to have some of the same problems listed below.
Here are the issues I have seen:
1. Items 12 and 13 on the Fender Jazzmaster parts list seem to be swapped and are shown reveresed on SD's layout as well, the result being you end up swapping the tone and volume pot. It works much better if you use the linear taper on the tone pot and the audio taper on the volume pot (duh). If you are repairing a guitar it would be easy to get this wrong as well following these diagrams. On the Jag SD diagram Audi taper pots are used for both volume and tone. You get all the tone control in about the first 1/8th turn of the knob????
2. One of the legs (the one that the tone cap goes to) of the 1 meg mini volume pots on the neck presets needs to be wired to the pot case (ground) and this subtle detail is not shown on the Fender or SD diagram and has to be done or the volume and tone presets will never work.
3. On the Fender diagram it's a coin toss on the output wiring because you can't tell which is the jack tip and which is ground.
4. The 3 way switch is a little unclear as to the wiring on the Fender diagram and on the SD it is really weird and not drawn in a way that is understandable.
The only really clear, correct diagram (especially the 3 way switch) I can find seems to be one in the book "Guitar Electronics for Musicians" by Donald Brosnac. However, it appears to also have copied over the tone and volume pot error. I swapped mine back and it appears to work properly now. I can't imagine they really intended for them to be that way.
Anybody know if there is a legitimate reason why they have the tapers on these pots seemingly reversed? Also, anyone know where the DIY forum is? I could have sworn there was one listed.
For folks who are building reproductions for themselves, you have to shield the cavities really well with copper foil and shield the pick guard (no aluminum foil) and then ground the the pick guard to the cavity well. The original design does not have a ground to the strings/bridge but I found this to be really helpful so I added a string earth ground by sneaking a wire up to one of the bridge post ferrules.
The guitar is really quiet now. It sure was a struggle to get it to play right. Thanks, to my master luthier teacher for pointing me to the real problem with the preset circuit!
Hope this helps others in the future.
Also, with the project Jazzmaster, no feedback problems so far! I don't know all the whys... but I wound the pick ups rather carefully and on the tight side but they are not potted yet and with all the care in shielding they don't seem to want to feedback even at pretty high volume levels. Even after testing the guitar with my teacher and a friend, using a vintage tube amp and some various pedals and a more current Fender amp it would not feedback. I brought it home and tested it with a tube preamp with two stereo tube amps running full volume on the pre amp, full volume on both amps and facing the amps and the guitar turned all the way up and could just get it to start to feedback.
I guess I don't no all the variables involved in the feedback dilema when it comes to jags and jazzmasters but since I like to wind pickups and I am always doing research I would like to hear peoples opinions about feedback problems and what can be done to cure it to make Jags and jazzmasters more versatile.
Cheers,
