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Post subject: 78 P-Bass Wiring Question ...?
Posted: Thu Mar 01, 2012 8:15 am
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Hello Forum I'm Bill ... fender player since '75

??

I have a 78 P-Bass that I picked up from a friend ... original owner.

Everthing is stock it appears but the wiring in corn- fusing me.
Not sure if he or his dad mod'd it. Any diagrams of stock 78 pbass wiring ?

Its a very buzzy bass ... the kind you don't take home to mutha

The white seems to be used as ground and the black as hot. There is a black
wire from the pup to the brass plate which I don't understand

looks like I have to find a photo site to link to a pic.


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Post subject: Re: 78 P-Bass Wiring Question ...?
Posted: Thu Mar 01, 2012 2:23 pm
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Location: Albemarle, NC
Hi Will, Welcome to the Forum.

FIRST: If you determine that the solder joints are original factory joints, do not disturb them. It will lower the value of the instrument more than most people realize to change even one solder joint in the original factory wiring.

There are several ways Fender has wired a passive P-Bass so that it works perfectly since 1951, however none I've seen use a white ground. While Fender does list some diagrams in the support area of the Fender website, those diagrams are for more contemporary production instruments, not vintage ones like yours.

The very best thing to do in your case would be to contact FMIC Consumer Relations and request a model year specific wiring diagram (schematic) for your P-Bass and that request should include the entire serial number from the instrument. The serial may help them find the exact diagram you need. Here is their contact information:
Fender Musical Instruments Corporation
Attn: Consumer Relations Dept.
17600 N. Perimeter Drive, Suite 100
Scottsdale, AZ 85255

Telephone: (480) 596-7195
Fax: (480) 367-5262
E-mail: consumerrelations@fender.com

I would not suggest having them fax it to you as the resolution will be higher in an emailed attachment. Some people say they get better results phoning in requests, so if you have free long distance service try calling them perhaps. If emailing allow at least a week. I can't imagine the staggering volume of calls & emails they must receive.

In the event FMIC can not provide an era correct diagram specific to your instrument or if they do not respond at all, there are two different wiring routes you could go. Either would work.

Possibly the better option of the two is to use the diagram that is posted for the American Vintage 62 P-Bass. I say that because your P-Bass has the metal base plate/shield under the pickup and that is a big clue to the wiring originally used. Often basses with that metal base plate will also have the separate metal pickguard shield under the pickguard. If both shields are present the 62 diagram would work perfectly. However at some point before yours was made, Fender switched to self-adhesive metal foil applied to the entire back of the pickguard, eventually scaling the foil area down to just the control cavity area. So if yours does not have the separate metal shield under the pickguard you can still add one for under $20 and they are available from any Fender dealer as Fender part# 0019723000. They are used of the AV '62 RI and currently available. You can order one online here: http://www.darrenriley.com/shop/cart.php?m=product_detail&p=176 or from a multitude of other online Fender parts dealers. These shields are a good upgrade over the self-adhesive foil for shielding purposes.

This next part is important if you decide to use the '62 diagram. The pickup on a '78 is significantly different from a '62, therefore the tone capacitor specified on the '62 diagram is a much higher value 0.1 cap, but you should ignore that and use the 0.05 (or the contemporary 0.047 equivalent value) with your CBS pickup. That is probably the value of the tone cap in there now so you can continue to use it. The 0.1 cap intended for a '62 pickup will sound too dark on any CBS era P-Bass pickup. The '62 pickup is a much brighter sounding pickup so it benefits from the higher value cap where in your pickup's case it would actually be a hindrance. So using the '62 AV P-Bass diagram is a good option for you with the pickup base plate present, so long as you use the lower value cap and add the metal pickguard shield if one is not already present. Here is the link to the '62 Schematic: http://support.fender.com/service_diagrams/bass_guitars/019-0209C_SISD.pdf

The second option is to use a contemporary control wiring scheme. It is less complicated and labor intensive plus does not require the metal pickguard shield. Just use the BLACK wire from the pickup base plate and the WHITE wire from the pickup as indicated on the diagram. This link is the one for the '99 American Standard P-Bass: http://support.fender.com/service_diagrams/bass_guitars/013-6000B_SISD.pdf

Either diagram will work. But In the presence of the pickup baseplate/shield I personally would go the slightly more labor intensive old school route. But that is just me. Your mileage may vary.


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Post subject: Re: 78 P-Bass Wiring Question ...?
Posted: Thu Mar 01, 2012 8:34 pm
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wow .... awesome Dave ... thanks so much.

btw ... love your write up on the 51 p work and I took out a bill lawrence p-46 for a test run
tonight in a 97 pbass at practice. amazing.

anyway ... back to the topic at hand.

All the parts of the pbass seem to be original ... except for the wiring job. It was just
totally whacked ... not sure how there was tone. a white wire between and to ground yet a black wire to the brass plate and the first volume post. The solder joints on the pups didn't look original. I checked the polarity of the pups and the neck one was north and bridge south.
Seemed to me that was backward.

I fired up the iron and disconnected all wires from the pups to the vol pot.
I lined up the north polarity in the bridge position and the south at neck postition.

I then started from scratch and followed the wiring diagram on the seymour duncan.
I had already shielded the cavity so I went ahead and added shielding to the back of the pickguard. Since the wiring wasn't original I figured I'm already off of being totally original.

When I got it all back together it was super quiet and the sound was fantastic.

I'll go ahead and get the original wiring diagram. I'll be curious to see what it has.

btw: I liked your review of the 62 pbass pups .. they seem to be very similar to SD antiquity II's but less expensive.

Thanks

Bill


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Post subject: Re: 78 P-Bass Wiring Question ...?
Posted: Thu Mar 01, 2012 9:56 pm
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Rock Star
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Joined: Thu Aug 07, 2008 3:12 pm
Posts: 6355
Location: Albemarle, NC
The Wilde by Bill Lawrence P-46 and the Fender Original P-Bass Pickup are both worthy 2nd Generation P-Bass pickups that are very affordable. Everyone should try them both. Bill Lawrence and Leo Fender both knew what they were doing. I use the bass with the Bill Lawrence P/J set in it a lot and can't imagine not having that bass around.

Tonight at our rehearsal I played the 04 P-Bass with an Fender Original P-Bass pickup in it. I frankly never really enjoyed the "R&B" (Ampeg B-15 emulation) setting on my little Line 6 rehearsal combo much until using it with that pickup in that P-Bass. It is the first bass that sounded right with it.


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