MIJ Jazzmaster Electronics Upgrade

[SemiOpaque]

Hi all, this is my first post, so Hello everyone.

I have a Japanese Jazzmaster, which I love. I just recently upgraded the pickups to AV65, which has been worthwhile. Although the pick up covers are the off white (cream/yellow) vintage style, which don't visually go so well with my pick guard since it is mint green. It looks quite 'muddy'. I wanted to use the existing white pick up covers that came with the guitar, however they don't fit since they're Japanese and metric vs imperial measurements so the pole pieces don't line up. I'm going to buy white covers from Mojo tone, and though while I was there and paying for shipping I'd like to buy the parts to upgrade the rest of the Electronics. I've researched on the internet and searched this forum but have been unable to find a definitive guide. I soldered the pick ups and have some 'limited' soldering experience so figure I'll give the rest a shot. This brings me to my questions –

1. What exactly do I need to buy in terms of pots? (don't mind leaving rhythm circuit pots since they're ok, and not used often.)
What are the 2 pots for volume and tone I need to buy? If I buy US size, I will need to increase size of the hole on the pick guard since the Japanese Pots are smaller, even the main ones, not just the rhythm circuit pots.

2. Will any standard switchcraft input jack and switch work? Or do they need to be specific to fit a JM?

3. Capacitors? What should I get? Lots out there about these but I'm not sure specifically what to get.

4. Cloth wire and anything else I need?

Thank you fellow offset fans.

[timtam]

Welcome to OSG.

Re wiring, if your MIJ has shielded conductor wiring, pulling it out for cloth covered/unshielded will probably make the guitar noisier. MIJ wiring, at least on some I've seen recently like that below, is better than (unshielded) MIA. If however you don't have shielded wiring or cavity/pickguard shielding, it would be worth shielding the cavities/pickguard while you're in there.


Asian pot shafts are usually smaller diameter, so bigger holes would be required for CTS for example. Your current knobs may also not match, depending on exact type ... check if pot shafts are split/splined or solid. Using full size Asian pots may save you those mismatches. Pots as in AV65 JM listed here ... both main pots are 1meg, volume is linear taper, tone is audio ...
https://www.fmicassets.com/Damroot/Orig ... A_SISD.pdf
There may be slight differences in the MIJ vs MIA wiring, for example where grounds are run, but nothing that changes actual function. Make a step-by-step list of all the changes you need to make.

Re-use the cap you have. The value is the only thing that matters. I would also keep your existing output jack.

Standard right angled Switchcraft toggle should fit if its measurements match your rout size ...
https://www.stewmac.com/Pickups_and_Ele ... witch.html
Fender version includes aged white tip ...
https://darrenriley.com/store/fender-ja ... 053694000/

There should be no tonal differences with these changes, although a very slight change could occur if the new pots are at the opposite ends of their tolerance ranges to what you have. You should think of the project as a fun way to learn, rather than something that is going to make a significant functional or any tonal difference.

[SemiOpaque]

Hi timtam, a fellow Melburnian thanks you for the very detailed reply. You know these models well!
My JM looks exactly like the model you posted in the image. The pick guard is shielded. And the cavity is painted black. That's interesting regarding the wiring being decent. It looks like a birds nest, but does the job. From what I've seen the wiring is different from other models, there is a ground wire going into the trem cavity. I haven't had any problems with the wiring. If anything I find it a bit bright and if I roll the volume down a bit I like the tone better. Would switching to 500k give me this result permanently?
Thanks again.

[timtam]

Hi timtam, a fellow Melburnian thanks you for the very detailed reply. You know these models well!
My JM looks exactly like the model you posted in the image. The pick guard is shielded. And the cavity is painted black. That's interesting regarding the wiring being decent. It looks like a birds nest, but does the job. From what I've seen the wiring is different from other models, there is a ground wire going into the trem cavity. I haven't had any problems with the wiring. If anything I find it a bit bright and if I roll the volume down a bit I like the tone better. Would switching to 500k give me this result permanently?
Thanks again.

Going to 500k pots may indeed mellow things just enough for you. Re the rest, it sounds like your MIJ has shielded cabling and cavity/pickguard shielding well covered. You could tidy up the shielded wiring with cable ties and by taping cable runs to the pickguard to fit nicely in the body routs like the neater harness suppliers (who somewhat paradoxically stick to unshielded cloth covered wire .. vintage looks over better noise insurance) ...

[SemiOpaque]

Thanks again for taking the time to respond and offer your insight, much appreciated. I think I'll try some 500k pots.

[jvin248]

.

One of those experience things you may benefit from ... if you are doing significant changes in the controls. Remove the existing harness in as much as one piece as possible and put it in a safe place. You may want that harness to replace if you ever sell the guitar or miss a tone you have right now. Then get your new parts and wire up a new harness. An unmolested wiring harness in a collectible guitar keeps the price up, heavily modded and the price goes down, even if the modded parts are more expensive than the factory -- the next buyer may not care for the mods (I found I don't like SD pickups so any time a post shows 'upgraded to SDs!' I discount the price because I'll have to swap parts). Buyers like buying factory original and making their own mods.


.

[MattK]

Agreed - my 1985 MIJ JM didn't sound great and had a pretty hideous tort - I ended up just lifting out the whole assembly including pickups and covers, and dropping in another pickguard with the new wiring and pickups. An early MIJ has some collectable value so I can put it back to original very easily.

[ChrisDesign]

Dimazio make good replacement pots:

DiMarzio EP1201 - 500 K Pot https://www.amazon.co.uk/dp/B000G8BAZ0/ ... nEbX4C89FN

I would throw a treble bleed on the volume. As the volume goes down, you maintain clarity. It takes a bit to get used to, but after using it I can never live without it.

fender tone saver: https://rover.ebay.com/rover/0/0/0?mpre ... 3929041431

The same, but cheaper: https://rover.ebay.com/rover/0/0/0?mpre ... 1957505037

As for cloth wire. It does nothing. Cloth wire is identical to plastic, only more expensive. Feel free to use it, but it won’t help your tone.

[timtam]

As for cloth wire. It does nothing. Cloth wire is identical to plastic, only more expensive. Feel free to use it, but it won’t help your tone.

That's true, but we're not really talking cloth vs unshielded plastic-covered wire (as in most MIAs) ... we're talking cloth vs stock shielded conductors on the MIJ. The MIJ's stock shielded conductor wiring is better than MIA's plastic-covered, single conductor wiring (or cloth, vintage or modern). The guitar also has a shielded pickguard and cavity shielding paint, so maybe the shielded conductors don't add much to the noise protection ... or maybe they do ... we don't have objective ways of evaluating that (except maybe blinded listening tests).

In any case, while one can argue that the MIJ pots may not be as good wear-wise as CTS (but 'small' does not mean 'bad') ... resistance is resistance .... but these MIJs are clearly better wired/shielded than most MIAs.

[SemiOpaque]

In terms of making changes to the existing wiring harness, do you think that's a problem with these modern (mine is 2015) MIJ Jazzmasters? These guitars are made in high numbers compared to older guitars. So they may never truly become collectable in the future? I've changed the pickups (will keep the originals safe), and based on the feedback from timtam, will leave the wiring alone since it's sounds decent. The only thing I will likely change is the pots to 500k. Even if they become somewhat desirable, I could always just revert it back to stock.

[SemiOpaque]

Thanks for the info re pots ChrisDesign, do I use this same pot you linked to for volume and tone? Do you know if these will be a straight swap for MIJ or do I need to buy new knobs to fit on these?

[hwestman]

+1 on the treble bleed.

Also I recommend slightly lowe values than standard for tone control caps.

I like 015 since it makes the tone control usable even when you dial it back a lot.

Regarding make and model of caps I am very sceptical with regards to boutique caps. I believe it is the value that matters.

AFAIK 1meg pots dialed back a bit will give the same sound as a 500k one.

But if you always dial it back it may make sense since you can keep it all the way up.

I was close to do that but have come to appreciate the (sort of) boost I can get when going from 8 which is my standard setting. Especially when using overdrive/ distortion.

[ChrisDesign]

Interesting. You say .015uF makes it usable, while I live by my .1uF caps. Everyone’s tone is preferential.

[ChrisDesign]

Thanks for the info re pots ChrisDesign, do I use this same pot you linked to for volume and tone? Do you know if these will be a straight swap for MIJ or do I need to buy new knobs to fit on these?

Without seeing your pots I cannot say. Dimazio pots are split shaft and ‘big’ size. To me, standard pots.

DiMarzio EP1201 - 500 K Pot https://www.amazon.co.uk/dp/B000G8BAZ0/ ... oEb331EG9G

This will work in volume and tone positions. Great to pair with a treble bleed: https://rover.ebay.com/rover/0/0/0?mpre ... 1970502737

[timtam]

Stock volume pot on JMs is linear taper, tone is audio (both are 1meg).
https://www.fmicassets.com/Damroot/Orig ... A_SISD.pdf