Sunday, May 05, 2013

Upgrading ALL Fender Jazzmaster wiring and electronics in one shot

(I'll finish my Japan trip report up shortly; I just want to write this up while I'm thinking about it.)

Today I'm working on my Japanese (CIJ) Fender Jazzmaster, surprisingly one of my most popular subjects here! I know other people have found my DIY tips helpful. I've already upgraded the pickups, tremolo, added shielding and Loctited my bridge. Now I've decided that if something's worth doing, it's worth overdoing - I'm just going to go ahead and upgrade all the wiring and electronics.

I've said before that upgrading the pickups will get you 95% of the way to a vintage sound. Doing the wiring and electronics should get you the rest of the way (unless you consider "m0j0" part of that vintage sound). Japanese pots, caps and switches are all of the "cheap" variety, and while they feel fine, they're not what Fender has traditionally used and I've never been convinced of their internal quality (and I know I'm not the only one).  The wiring is similarly junky.

This is what's under a Japanese Jazzmaster pickguard (not the copper shielding; that's mine). It's just kind of a mess of generic undersized electronics and thin plastic-insulated wire.

This is what we'll be replacing all that with:
That's a pre-made wiring harness that I bought off Ebay. There are a couple of guys doing this on Ebay right now, I bought the cheaper one. I think this is a good deal. There are several companies selling Jazzmaster wiring kits, and they generally cost around $70 just for all the parts. If you buy everything separately, it comes out to around the same amount. I bought this completed harness for $99 - I think the $29 markup over buying a kit is totally reasonable for someone to have done all the work of cutting everything to length, soldering everything properly and then organizing it all.

This harness comes with CTS potentiometers, Switchcraft switches, Vitamin Q paper-in-oil capacitors and cloth covered wire. That's mostly the stuff used in both vintage and AVRI Jazzmasters, although the caps are different (supposedly an upgrade even to American JM's) and the main pickup switch is cosmetically different (burled nut vs. hex nut).

It also came with a wiring diagram, although I didn't use it because it was confusing and didn't even seem to match the work already done! Instead, I just copied how my CIJ and AVRI wiring were hooked up already.

I also bought 2 feet extra of black cloth covered wire for the main ground lead - I recommend that. It cost me $1, also on Ebay.

Some specific comparisons:

Japanese tone and volume pots. Note the tiny (ceramic?) capacitor.

CTS tone and volume pots. It may not be obvious but these are actually much bigger - consider that the distance between pots is the same as the Japanese ones. Note the big PIO cap attached to the bottom of the pot. I was not even sure this would fit in my JM cavities!

Japanese roller pots and cap.

These pots aren't actually bigger, but the knobs are and obviously there's another PIO cap. Heavier gauge cloth covered wire is really obvious here!

The process for installing the new wiring harness is pretty straightforward - you just desolder your pickups, unscrew everything from the pickguard, then do the reverse for the new stuff. Optionally you can remove the tremolo so you can get at your ground wire and replace that too (I did that). There is one little hiccup that I knew was coming:

Because the new pots are so much thicker, you do need to widen the holes in the pickguard for them. Dremel to the rescue! I found that its smallest sanding attachment was perfect to drill through these holes and make them just the right size. Beware, though - it will literally start to melt the pickguard. There will be smoke, and it will stink.

Also, if you do not have any sort of metal shielding in your body cavities (and CIJ/MIJ Jazzmasters don't come with it), then you'll need to figure out how to ground your pickups some other way. This new harness I bought didn't have the grounding post for the neck pickup as my original harness did, and the post used for the bridge pickup is kind of tricky because it's already got a wire soldered to it. I decided to just attach my ground leads to my copper shielding - that's the way my AVRI is wired (and it's actually what the wiring diagram says to do).

The new harness attached to the pickguard. Now compare the volume and tone pots to the picture at the top...

Here's a picture of my soldering in progress. That middle post in the switch there is where the bridge pickup is grounded from the factory, but I couldn't even get that solder to melt on this new harness. (My soldering iron sucks.)

Here it is pretty much done. I soldered my main ground wire to the tone pot, but I hadn't run it through to the trem yet at this point.

One thing that I always find annoying when working on any sort of Jazzmaster is just how tight the space ends up being when you try to reattach the pickguard. In my case, I rested the pickguard on the body, strung up one string and tested everything out, and it all worked fine. I was pleased! However, actually getting the pickguard seated properly required a lot of jimmying of wires to make everything fit. The main problem is always that bundle that runs below the neck pickup, but I also had problems this time around the rhythm switch/roller pot area, which just didn't seem to have enough room.

At some point in all that jimmying, I lost functionality of my rhythm switch. Blah. Should just be a short.

Another reason to crack my pickguard back open - the new pots are too tall for my (real 1960's) witch hat knobs. Easy fix - just need some rubber or nylon washers to stick in as spacers between the pot and pickguard underneath. There's plenty of screw thread above the pickguard to allow you to do that.

Next day update: All fixed!

The rhythm switch problem was a short in one of the roller pots' wiring, caused by jamming everything in there too tight. I've learned that on Jazzmasters, sometimes all you've gotta do is just figure out a way to spread things out a bit.

Pots are also the proper height now. If you have this problem, look for a #32 top bibb gasket from your local hardware store. It's a perfect fit between the pot and pickguard to act as a spacer (the locking nut still goes on top, just under the pickguard). As someone pointed out in my comments, if you have pots that aren't separately grounded, then a rubber gasket may not be the best option unless you want to add ground wires to your pots. In my case, both of my pots have ground wires already so I didn't need to ground them through contact with the pickguard shield, and in that case using rubber as a spacer works fine.

This thing's a tone monster now. It's smoooooooooooth. That's the word I'd use. It's like Billy Dee Williams in his prime. I'm still using Seymour Duncan Antiquity II pickups, not the stock CIJ pickups. This guitar already sounded great, but now it really just has a smoothness and warmth that I swear is new. I'm not sure if I like the linearity of the tone pot, but I can always change that individually if I so choose.

I'd put this thing up against any other Jazzmaster. Any.

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About This Blog

This is increasingly not a blog about Alphabet City, New York. I used to live in the East Village and work on Avenue B, but I no longer do. Why don't I change the name if I'm writing about Japan and video games and guitars? Because New Yorkers are well-rounded people with varied interests, and mine have gone increasingly off the rails over the years. And I don't feel like changing the name. I do still write about New York City sometimes.


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