Electronics for Fender Power Jazz Bass Special

[Welkinmusic]

Hello all... been a fan and lurker here for a long time, but this is the first time that I am truly stumped and need some assistance.

I own an '84 Power Jazz Bass Special and love it. I need to replace two of the pots though (shafts broke off), and have zero idea of what to replace them with.

It would be convenient to replace all three pots and both switches, sure... but I doubt I can find any replacements with the original/correct specs.

Advice, links, etc will all be welcome... thank you ahead of time for any help y'all can give me!

edit: I thought it was an '82 because of the serial number, but after checking, it's an '84

 

[fhm555]

If it's the three knob and single toggle I'd bet it's the same guts as the Heartfield basses.

Do the controls look like this?

 

[Welkinmusic]

Wow, gorgeous bass! I am going to do a bit more research on your suggestion. Heartfields indeed were made at the same factory (Fujigen) as my Power Jazz, so who knows? My concern is that the Heartfield has only one switch (pickup selector I am guessing), while the Power Jazz also incorporates a toggle for the active electronics.



To the best of my knowledge, this is what my Fender schematic looks like:



If there are any experts that can tell me what would be a comparable replacement, I'd sure appreciate it!

Thanks again for the heads-up on the Heartfield... going to take a look now.

 

[FunkHead]

Someone on here has the electronics F/S for a P-Bass lite. The pots will work.

 

[Isotonic]

No, those won't work. The Power Jazz Special was unique as far as I can tell. As far as switches go, there should be two of them. A regular three way and a three way mini switch if I recall correctly. Those should be easy to find on Mouser.com or Digikey.com. Just measure carefully and look for a match. There should be dozens of options. The pots are a bit trickier because the ohm value is anyone's guess. I suggest you do some hearty Google searching. I was able to infer the value of the pots on my vintage active Seymore Duncan P, but it took a while.

The electronics on the PJBS were pretty cool. You could get a few great tones on it and sme really cray farout sounds. The engineer who was recording the band I was in at the time really liked the way it recorded. I think there was a frequency sweep on there and something similar to the Z switch on the Audere preamp. I really miss mine. Don't give up on it. I wonder if there is a way to measure the existing pots to get an idea of the value.

Have you looked for any numbers or codes on the back of the pots themselves?

 

[Isotonic]

I just saw your picture. That looks just like my old bass.

 

[Isotonic]

I found this thread and this image. If you find the OP of this image from the thread, he states that he drew up a schematic, though the image is missing. If you can manage to contact him, he may still have it.

 

[Welkinmusic]

Thank you all for the replies.

Isotonic, you're right... there is a sweepable frequency boost on the PJBS along with the mini toggle that controls the active circuitry. It indeed sounds great not only in the studio but on stage; it is the best overall tone control I have experienced.

I posted a schematic in this thread; think I can just print that out and take it to a good guitar shop and/or luthier?

Guess I should have gotten a replacement package years ago just in case, huh?

 

[Isotonic]

As long as you have the values of the pots they should be fairly easy to source, and inexpensively. I didn't see the schematic originally. Sounds like you are most of the way there. A of luthiers are not very good electronics techs. They can do the standard setups, but this may be beyond some of them. If you show them the schematic and it makes sense to them, that is a good sign. Good luck.

 

[Welkinmusic]

Ok, last request, I promise!

Looking at my schematic, I would need what... two 50K pots and a 20k (for volume I am guessing)... sound/look right?

I have found a couple of sites that sell guitar pots, and want to make sure I get the right ones. What is the difference between a regular and a mini? Which would a Fender bass use?

Thank you again everyone.

 

[Isotonic]

This might be helpful.

http://www.beavisaudio.com/techpages/Pots/

Looking at your schematic, it seems right to me. Also, there are a couple of 10uf electrolytic caps in there. Those caps need to be changed as the electrolyte is probably dried out, the ESR way up and the values drifted. Look to Digikey or Mouser for Panasonic FM, or Nichicon Muse caps. Don't scrimp on quality here.

I wouldn't necessarily look to guitar sites for these pots as they are extremely unusual values for a guitar. I would also look at the above sites, who stock hundreds of options. You may have to measure or look for the measurements of typical guitar pots for sizing. You want to get the longer shafts since you are not going through a pick guard. Buy the best you can find for durability. CTS has a very good reputation for pots. Notice also that you schematic calls for Logarythmic taper. That is important too.

Minipots are for control cavities that are very crowded. Post a pic of your control cavity.

 

[heavymetal0061]

I have an 1987 MIJ PJBS that i bought with all original working parts,,,for some dumb reason I decided to pull out the electrics and replace them a normal PJ pick-up set and wiring and add a EMG afterburner preamp boost since i had the 9volt battery compartment,, Now I wish to reinstall the original electronics.. I cut the pick-up wire's leaving the A.T.E circuit, TBX and Frequency Sweep wires all together,,looks like I have to just install a volume pot and attach pick-wires with battery power supply,, BUT I am unable to figure out where things go,, very different wiring set-up! has anyone found a wiring schematic or even pictures of this set-up,,,,Should'a Could'a Would'a wish I just have left the darn thing alone!,,,