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Post subject: Reuild a Fender JP 90
Posted: Tue Mar 10, 2009 10:34 am
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Hello people. I've started to rebuild my old Fender JP 90, but i have some problems and i hope anyone can help me.

I can't read the details of the potentiometers, it's to old. Do anybody know the numbers or letters, that i should know. I want to buy some new one.

The second thing is, that the pickguard is destroyed and i can't find a new one.

P.S.:I'm german, so please explain the things simple, ok?!


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Posted: Tue Mar 10, 2009 12:46 pm
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Potentiometers: with single-coil pickups, you will probably want 250K pots.

CTS is a good brand.

Here's a link so you can see some options:

http://www.guitarpartsresource.com/elec ... erpots.htm

Choose 250K pots with either split or solid shafts depending on the knobs you want to use. Split shafts are for push-on knobs like on a Stratocaster guitar and solid shafts are for knobs with a set screw, like on most Precision and Jazz basses and Telecaster guitars.

Here is a source for JP 90 pickguards:

http://pickguards.us/priceotherfender.html


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Posted: Wed Apr 22, 2009 12:42 pm
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Hi, Ive just bought a JP-90, almost new (because its hasnt been used)...but i would like some information about it. For example what does J) 90 stands for, or where to find more pickguards, cases, or replacemente picks.

I do know its a MIA bass, it has two picks (one for precision bass an one for jazz bass, and swithc). I got it serial number but i cant find the way to check it with the Fender website.

Thanks for any help.


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Posted: Sat Apr 25, 2009 12:51 pm
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pablofe wrote:
Hi, Ive just bought a JP-90, almost new (because its hasnt been used)...but i would like some information about it. For example what does J) 90 stands for, or where to find more pickguards, cases, or replacemente picks.

I do know its a MIA bass, it has two picks (one for precision bass an one for jazz bass, and swithc). I got it serial number but i cant find the way to check it with the Fender website.

Thanks for any help.


FIRST, I agree with what George said. If you don't like the stock pickguards at pickguards.us then check with JEANIE pickguards. GREAT work and a huge selection of classy materials to pick from. Really good people. Their link is on the REPLACEMENT/UPGRADE BASS PARTS addendum page from my RESOURCES page which is the link in my forum signature below.

If the pots are noisy you might could clean them with contact cleaner. Remove the pot from the pickguard, put someone under it like a newspaper to catch any dripping product and spray down the shaft and give the pot about 100 turns full travel. This might let you keep your original pots, but if it doesn't work then you'll need new ones. I only usually replace pots if I don't like the quality of the pot like on import basses or if it doesn't improve with a spray or two.

PABLOFE, "JP90" stands for JAZZ PRECISION 1990 which was the first model year they were made.

You can find out your year by going to my RESOURCES page from the link in my forum signature, then clicking on INSTRUMENT HISTORIC DATA and once on the Data page you need to go down to the "Guitar Dater Project for FENDER" link and click it. I've yet to find a Fender USA, Mexican or Japanese bass yet it didn't nail.

JP90's are really nice instruments and I wish I had mine back which I traded for a P-bass special. What I missed about it was the light weight, great neck, killer passive tone and the toggle switch. That toggle is a really nice feature. This is one of the best passive PJ basses Fender ever did. They should do a reissue. A great gigging bass!


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Posted: Sat Apr 25, 2009 1:01 pm
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Also a standard Precision style case will work. I'm not on world tour so I just use Fender Gig Bags now, even for my non-Fender basses because they are great bags.

I keep after my nephew who designs products for Oakley to design some really cool guitar and bass bags for Oakley. He's really a great designer but I just can't get through to him how well a colorful bag would sell. I'm tired of black, black, black...or maybe tweed which shows dirt to much. Lots of people like the leather bags, but I don't like leather because of the smell, especially when new. I'm also not sure what the chemicals used in tanning leather do to the finish on an instrument.

I'm down to one hard case but usually there is nothing in it. LOL.


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Post subject: Fender JP-90 Information.
Posted: Thu May 28, 2009 8:38 am
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Hello, I have a Fender JP-90 color red. My bass has two volume controls and a single tone control. Fender did build them with pickup switches also to enable switching pickups on or off. The "JP" stands for Jazz-Precision due to the Jazz pickup in bridge position and the Precision pickup in the neck position. The "90" stands for the year 1990. These basses where only built in 1990. It should say Made in USA right under the JP-90 decal. If your bass does not I don't know what to tell you. The neck is more of a Jazz bass style neck profile. The pickups where made for the bass so there are no direct replacement. I replaced mine with Genuine Fender pickups. Original "59" Precision and a Vintage Jazz. I kept the originals just in case I want to put the bass back to original condition. I also put a Badass II bridge on mine to give it better sustain. This bridge is a huge piece of steel! I hope this helps you out.


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Post subject: Re: Fender JP-90 Information.
Posted: Fri May 29, 2009 11:25 am
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michaelmiller1332 wrote:
Hello, I have a Fender JP-90 color red. My bass has two volume controls and a single tone control. Fender did build them with pickup switches also to enable switching pickups on or off.


The Fender specifications for this poplar bodied instrument called for one master volume and one master tone pot. (See specs pasted below.) I'm guessing your Torino Red 1990 model was modified before you got it. I've never seen one with two volume pots that wasn't modified. They may exist but were never supposed to be made that way and would not have passed inspection which has been very stringent on the USA stuff since the Corona plant opened. I'm guessing yours has an aftermarket mod. I could tell by inspecting the wiring job.

michaelmiller1332 wrote:
These basses where only built in 1990....The neck is more of a Jazz bass style neck profile.


Again these statements don't jive with the official Fender specs below which states it was produced from 1990 until 1993. I personally had a '91-'92 model with a 92 serial at one time. Also, the neck width profile was 1.625" which would make it a P-bass neck profile rather than a J-bass neck. The neck on mine felt thin compared to my 76 P-bass, but the width and string spacing was definitely P all the way.

michaelmiller1332 wrote:
The pickups where made for the bass so there are no direct replacement. I replaced mine with Genuine Fender pickups. Original "59" Precision and a Vintage Jazz. I kept the originals just in case I want to put the bass back to original condition. I also put a Badass II bridge on mine to give it better sustain. This bridge is a huge piece of steel! I hope this helps you out.


Keeping the original pickups was a good idea. According to the JP90 specifications the original pickups were "Standard" P-bass and "Standard" J-bass. This would be the exact same pickups as on the American Standard basses of similar vintage with the same dimensions, winding, pole material, pole spacing, covers, etc. Since this is a made in USA bass, any J or P pickups for another Fender USA bass with "Standard" pickups would fit. HOWEVER, matching the pickups would be a critical consideration and a matched set would be best. I'd have a custom winder like Lindy Fralin match them up since there is no way to blend them as there are no separate volume controls or a blend control.

In my opinion, more sustain is not always a good thing depending on the style of music you play and your personal playing style. If you feel like you need more sustain then a high mass bridge would help in that regard but is not always required.

The OFFICIAL FENDER SPECS for the JP90 follow:

Model Name: JP-90
Model Number: 014-4100-(Color #)
Series: Standard Series
Body: POPLAR
Neck: MAPLE
Fingerboard: ROSEWOOD
No. of Frets: 20
Scale Length: 34" (864 mm)
Width @ Nut: 1.625" (41mm)
Hardware: CHROME
Machine Heads: STANDARD
Bridge: STANDARD
Pickguard: N/A
Pickups: 1 STANDARD PRECISION, 1 STANDARD JAZZ
Pickup Switching: 3 Position Toggle (Neck, Neck/Bridge, Bridge)
Controls: MASTER VOLUME, MASTER TONE
Colors: (706) BLACK, (758) TORINO RED, (780) ARCTIC WHITE (Poly-Urethane Finish)
Strings: Dynamaxx 1200L
Unique Features:
Source: CORONA (US)
Accessories: None
U.S. MSRP: $499.99 to $529.99
Specs: Prices and Specifications Subject to Change Without Notice
INTRODUCED: 1990
DISCONTINUED: 1993


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Post subject:
Posted: Fri May 29, 2009 11:45 am
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pablofe wrote:
Hi, Ive just bought a JP-90, almost new (because its hasnt been used)...but i would like some information about it. For example what does J) 90 stands for, or where to find more pickguards, cases, or replacemente picks.

I do know its a MIA bass, it has two picks (one for precision bass an one for jazz bass, and swithc). I got it serial number but i cant find the way to check it with the Fender website.

Thanks for any help.


These oddball shaped pickguards are hard to find for sure. They do tend to crack or break around the output jack. One reasonably priced pickguard source for JP90 guards is Pickguard Heaven. There is a link to them on my website. Click the link in my forum signature below and then click on REPLACEMENT/UPGRADE BASS PARTS and then on the link for Pickguard Heaven. Also if you wanted a custom pickguard I'd recommend you check out the link to JEANNIE there.

To date your instrument go to the INSTRUMENT HISTORIC DATA page link on my website's Resource page. Try the GUITAR DATER PROJECT FOR FENDER link. Scroll down and type in your serial, check the appropriate box for USA and go! Let us know the result of this query please!


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Post subject: Hi
Posted: Tue Jun 16, 2009 9:42 am
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Hi.
I'm thinking of changing my pickups and all the wiring with it. Do you guys have some good ideas on witch pickups to go with and what potentiometers should I go with?
The music is most likely funky rock. :)


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Posted: Wed Jun 17, 2009 8:35 pm
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ON a JP90 the ORIGINAL pots are specified as 500k. The ORIGINAL capacitor is a 0.068 MFD. A link to a very basic JP90 schematic is posted on my site’s DO-IT-YOURSELF SETUP & MAINTENANCE page accessible from the link in my forum signature below.

One of the advantages of the JP90 design is the ability to truly SOLO each pickup without the other pickup loading it down. You can also put both pickups online but then have no way to control their individual volume in the mix. The following upgrade option would take that switch option away, but would in exchange give you the advantage of being able to BLEND the pickups at your will.

The blend option, using only standard pots becomes a possibility with the WILDE Bill Lawrence P/J Matched set. You don't have to buy any special blend or stacked pots, just normal instrument pots. The set is about $160 plus shipping. The schematic included with them is for a Master Volume/Blend/Master Tone arrangement requiring THREE pots. The catch is that I'm not 100% certain the pickups will fit. They PROBABLY will fit but I’d make certain first. Trace your original pickups precisely and send the tracing to Bill Lawrence’s shop and see if his set will fit without having to modify your instrument. Another thing to check is that you have room in the pickup lead channels leading to the control cavity for an additional wire to fit since the WILDE pickups each have three lead wires.

This WILDE Bill Lawrence P/J set requires 3 pots which would also mean a new pickguard custom drilled for three pots instead of the original which has two pots and one mini-switch. You’d need to send your existing pickguard MARKED with exactly where you want the pots to go and specify that the mini-switch hole not be drilled as on the original. Tape over the switch hole and mark it with a big “NO” maybe. You’ll need to plot out where you have room in the control cavity for 3 pots in a row. Jeannie Pickguards and other custom pickguard services can then custom cut and drill a new pickguard for you. In addition to new pots you might want to replace the jack too with a new Switchcraft or the original might be just fine.

The WILDE P/J diagram specifies 250K pots, one 0.05 MFD capacitor and also a second VARIABLE tone bleed capacitor position. I would initially install a SPRAGUE VITAMIN-Q 0.047 MFD in the position calling for the 0.05 MFD. In the variable treble bleed position the design states you can use your choice of a 0.02, 0.03, 0.05 or 0.1 MFD cap. I went with the 0.02 value which translated to a 0.022 MFD PIO cap after trying one of each value Poly cap (Radio Shack) attached with alligator clips (Radio Shack.) Ceramic or Poly caps are really cheap so just get one of each value and alligator clip them in to try them like I did and pick the one that gives you the sound and tone control you like best. Just because the .02 worked best for me doesn’t mean you will also like it best.

Once you know the value you like for the variable position THEN track down and buy the closest value available in a Sprague Vitamin-Q or similar design PAPER IN OIL capacitor to replace the Poly cap. There are numerous brands of MADE IN USA PIO caps other than Sprague Vitamin-Q such as Cornell-Dublier, Mallory, Gudeman, Philco, etc but they are all pretty much the same design as they were military spec items. There are also Soviet/Russian made PIO caps that lots of people use with great results.

The PIO caps will cost more but the improvement they make is worth it. You won't find a 0.05 MFD PIO cap but the 0.047 MFD is so close that it doesn't matter. For both PIO caps you will want to stick to the 200 volt or smaller voltage varieties due to size constraints and because higher voltage caps do have a tonal difference.

If money is a consideration you can just buy two Sprague Orange Drop 225P MYLAR Film Caps in 0.47 and one each close to the 0.022, 0.033 and 0.1 values specified. Which would total under $13. Those values are very close to the spec sheet. The 225P’s sound much smoother than the more widely available Sprague Orange Drop 715P & 716P caps. The 225P’s are actually a little bit less expense! Those 715P & 716P caps are the ones most online guitar parts dealers offer. The 225P Mylar caps are more squared off looking than the rounder looking 715 & 716 Poly varieties. Tonally, the difference between a Sprague 225P Mylar cap and more expensive PIO cap of the same value is barely audibly perceptible. The only disadvantage to the 225P Mylar caps is that they are rated for use only up to 100 degrees Celsius which translates to 212 degrees Farenheit. If your bass gets that hot the cap could fail, but frankly if it gets that hot it would not be usable anyway since it is probably in a building or vehicle that is on fire at the time and the pickguard is melting.

If you want to retain the unique mini-toggle switch and original knob arrangement that is perfectly understandable and in that case another pickup option I could recommend is to have Lindy Fralin make you a matched P/J set.

The difference between the two pickups is that the Fralin set will sound true to Fender vintage design pickups while the WILDE set by Mr. Lawrence will be a modern design with three leads instead of two leads. Only Mr. Lawrence is making this exact design so far as I know. (There are also Lace pickups with three leads but the WILDE pickups are still made in a different way. For example the WILDE’s are sealed in an epoxy resin.)

A third option would be to use the existing pickups or have them rewound if they are weakening or replace them with Fender Vintage pickups which should fit fine and sound original.

To check out the WILDE pickups or the FRALINS, click the link in my signature below and then click on the red title REPLACEMENT/UPGRADE BASS PARTS. There are also several sources listed there for CTS Pots and PIO caps on the same page with the pickup shops.

Good luck!


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Posted: Thu Jun 18, 2009 2:25 pm
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Thank you so much!!
I'm a lot smarter thanks to you now :)
So I'm thinking of going with Fender vintage pickup's and 500k pots. As far as the capacitor goes I can't find a 0.068 MFD so do you think using .047 MF would be ok? I know smaller capacitors will have a higher cutoff frequency and the sound is brighter in the bass setting because only the ultra high frequencies are cut. It's my first time to do that and I home I wont mess up the sound :?


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Posted: Fri Jun 19, 2009 2:09 pm
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Tulp wrote:
As far as the capacitor goes I can't find a 0.068 MFD so do you think using .047 MF would be ok?


1. Stick with the 0.068! If you are going with the factory stock Volume/Volume/Master Tone with Mini-Switch Pickup Selector toggle setup, then I would do it to the original factory specs. The reason they used those 500k pots and slightly darker 0.068 cap was to achieve a particular tonal and pickup volume balance between the matched P/J pickup set. I saw this same 500k pot and 0.068 cap scheme in an Ibanez TRB70 P/J bass I overhauled as suggested for your JP90. The output volume is a little lower but the pups sound more balanced. Use the original poly cap in it now if you need to, it will work until you can get your hands on an upgrade PIO or Mylar film cap.

2. Axegrinderz has 100 volt Sprague Orange Drop Mylar (Polyester film) 225P's in 0.068 value for $2.50 delivered to your USA mailbox free. Your profile doesn't state your location, but if you are outside the USA they'll still mail to you at a very reasonable price. Their link is on the REPLACEMENT/ UPGRADE BASS PARTS link on my site. Click the RESOURCES page link in my signature below. There are also Soviet/Russian PIO caps made in the desirable 200 volt size made in a 0.068 value. Ask Axegrinderz if they have any. They don't list them on their site, but it is a slightly oddball value and they may have a few around, so ask via email. They are very responsive and helpful.

3. One other thing. Getting a matched pickup set is very important with this design since you don't have any way to individually control pickup volume or blend. If they are not balanced properly one will completely dominate the other when both pickups are active in the circuit.


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Posted: Sat Jun 20, 2009 7:49 am
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Thanks!
I'll look for the 0.068 :)

On pickups I'm not so sure anymore. I was going to go with Fender Vintage P bass pickup set for neck and for the bridge I'm not so sure anymore.I was thinking of buying SEYMOUR DUNCAN SSTK-J2B Hot Jazz Stack Bass Pickup. Do you think It's a good idea? What if they don't match.
It's just that this is my first time ever to modify an instrument and I don't want to mess up. :oops:


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Posted: Sun Jun 21, 2009 2:47 pm
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If you want the Fender Vintage P pup then the Vintage J pup might be a better match. Since there is no individual volume control in the original set up they really must be pretty close in output level to achieve a good balance. Best bet is to buy a matched P/J set. Lots of the custom pickup shops routinely do balanced P/J sets even though it may not be on their page of stock offerings.

Another option would be to use any pickup combination you want and then if the balance is not to your liking you can add a "trim" pot to whichever pickup is hottest. Due space constraints it would be best to use a split-shaft mini-pot for this and conceal it within the control cavity and then use a screwdriver to adjust it. You then just pad down the hotter pickup to balance the pair perfectly. This is a "set it and forget it" solution. You could secure the trim pot to the back of the pickguard inside the control cavity with 3-M doublesided sticky foam which will hold it indefinitely. The hassle is getting it set, but once it is right you shouldn't have to adjust the trim pot again. You'd need to plug the bass directly into something with a VU meter such as a really good mixer or a computer with audio recording software. (I'd use the huge VU meter on my Adobe Audition Recording software which covers about the full width of the computer screen and is very sensitive.) Use the VU meter to get the pickups balanced by soloing each pickup and comparing the output level on the VU meter until you get them pretty much even. Make sure any compressors are out of the loop when you do this because a compressor would cause bogus VU readings. You'd need to check primarily in the middle notes since inherently the J pickup will be stronger on higher notes and the P pickup on lower ones. If you get them balanced in the middle then it should work out fine.


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Post subject: Re: Reuild a Fender JP 90
Posted: Sun May 11, 2014 6:11 pm
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I hope I don't get chastised too much for reviving this old thread. I just bought a JP-90, white. I'm thinking of changing the color and possibly even modify the knobs, add one for a mix between pups vs. the 3-way switch.

Any advice would be greatly appreciated.

Image


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