EDIT: pickups are in, new electronics soon! scroll down

I've had my Yamaha 120sj for quite a while now and through the acquisition of other guitars, I've discovered that I'm just not satisfied with the tone anymore, lately it seems that it only sounds good really distorted, and even then it seems that it can only sound like an incredibly fat person playing an incredibly fat guitar, so I've decided I want to mod it to make it a million times more versatile.

A bit of background: Never done guitar wiring mods, but I've read a lot about it, and I can solder. I play blues rock (early black keys), garage/pusk-ish rock (the stooges, black lips, the king khan and bbq show, etc.), ambient (explosions in the sky), funk, shoegaze, and some weird-ass experimental shit.

Here's a pic from google

The only difference is that I have black string saver saddles on mine.

I was thinking of replacing the dark sounding stock humbuckers with a gfs mean 90 in the neck (for a fat bluesy tone) and a gfs surf 90 in the bridge (for a trebly, garage-rockish tone). I was also thinking of replacing the pots with push-pull ones to have a parallel/series switch, and maybe either a phase switch or vol/tone bypass, to expand the number of sounds even more.

I recently read about "50s les paul" wiring, with the tone pot connected to the volume output instead of the input. Apparently it makes the tone control more even and reduces the amount of treble lost when rolling back the volume. (source: http://www.premierguitar.com/magazine/Issue/2007/Feb/The_Telecaster_Mod_Guide.aspx)

Should I get 250k (instead of 500k) pots since I'm changing to single coils from humbuckers? Or would just rolling back the tone do a good enough job of damping the extra highs from a 500k pot?

I've drawn up a potential wiring diagram but I seem to have lost it, so once I draw it up again, I'll upload it.

Any answers/comments/suggestions are very welcome!
Last edited by &baconstrips at Jan 15, 2012,
I've seen 500s used with single coil pickups, but if you're buying already, might as well go with 'standard' values and get 250s. You probably wont notice much difference.

I'd go with series/parallel and out of phase and skip the bypass. Or drill a hole and have a new switch for bypass. Be fearless.

Or, is the blade switch a three position? Maybe you could upgrade that to a 5 position and use it for phase? (freeing up one pushpull for bypass)
The 5 position switch seems like a cool idea, but all the tabs on those confuse me, and I like the simplicity of a 3 way switch while playing. I find the 2 and 4 positions are a bit finicky.

Thanks for the suggestions!
Here, I came up with a wiring diagram. Does this make sense? push-pull on the tone pot is for series/parallel, push-pull on the volume pot is for phase on the neck pickup. When the tone pot is pulled up, it's supposed to bypass the 3 way switch. I made this from a bunch of stuff I found online. red=hot, black=ground

It would be good if anybody who knows a lot about guitar wiring could chime in on this.

Also, paint ftw
Last edited by &baconstrips at Jan 7, 2012,
Yeah, I think that's right. I had to think about the series/parallel one for a while. When its in series, the pickup selector switch is 'shorted' so they are both on regardless of its position. Good work.
Overdue update with questions and reviews at the bottom:

I got the pickups a few days after christmas, installed them before getting the push-pulls to see if I like the tone.

Here's how it looked before, only mods are graphtech string saver saddles and a plastic pickguard I made myself which is stuck on with double sided tape because I don't do committment very well. That will be changed soon.

Here it is with the mean 90 and surf 90.

Originally I was thinking of scuffing up the pickups to make it look a bit relic, but then I realized that's silly cause most of the guitar is in pretty good condition. Instead, I think I'll just be a bit less careful with it and see how that goes.

Quick review of the pickups

Mean 90: Great smooth clean sound with lots of detail. Mids are pronounced, but not as much as expected. Nice growly overdriven tone with ample bass without getting muddy. Not as agressive as the p90s in another guitar of mine, but still some bite. Would probably sound better on the lower strings with a more normal set of strings (I really like the feel of 10-52).

Surf 90: Higher output than expected, bigger sound than expected too, I was kinda hoping for something a little bit weaker and thinner. Scooped mids with more bass than expected. Very articulate clean, tight and kinda twangy, definitely surfy, but less so than I expected. Loses a bit of the tight surfy character with overdrive. Turning the guitar volume down a bit gives a nice old school garage rock tone. Turning the tone down a little, but keeping the volume dimed makes it sound surprisingly big.

They have a pretty good contrast with eachother and the output seems to be about the same, but the surf 90 seems to have a bit more presence cause of the added highs. I mounted the surf 90 backwards cause I think it looks better and gfs said it shouldn't make a difference in sound.
The switch's middle position is not what I expected at all. It is very thin and "quacky" sounding, almost like a cocked wah or out of phase pickups, pretty funky. I checked the wiring about 100 times to make sure I didn't do it out of phase by accident. I still think its a useful sound, pretty unique, and the volume drop helps clean up the sound a bit. What is causing this? Will my out of phase mod make it even more wacky? Wired in series, would it sound the same but just louder?