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Author Topic:  Fender Trapezoid pickup
Jim Palenscar

 

From:
Oceanside, Calif, USA
Post  Posted 16 Nov 2020 7:27 am    
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I have recently been tasked with restoring a 1950 Fender D8 Deluxe lap steel. Besides the usual problems(bad lollipop tuners, etc) one pickup is decidedly thinner than the other and I'm in the process of rewinding it. Previously I made a pickup resistance chart (I know there are tons of other variables) from lap steels that I had at the shop and I wrote down that a triple 8 Fender Deluxe measured roughly 3.75k on all 3 pickups. Other references that I found going through forum archives said to use 42g wire and put 10,000 turns on it resulting in about an 11k final resistance. One other problem I've encountered is that the better of the 2 sounding pickups doesn't give a reading either (my ohm meter is working correctly as I was able to measure lots of other pickups at the shop with no problem) so I'm thinking about rewinding both of them so the output will be balanced. I have 38, 42, and 44g wire at my disposal. Any thoughts would be appreciated. Thanks in advance.
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Scott Swartz


From:
St. Louis, MO
Post  Posted 16 Nov 2020 7:43 am    
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Jim,

I copy pasted saved the following from an Ask Seymour (Duncan of course) webpage from about 15 years ago I think. I don't think he would post disinformation, and I have not changed it, so maybe it will help you out, and HF equals Heavy Formvar as used on Strat pickups and lots of other Fender pickups as you can see below. PE = Plain Enamel.

Tab:



319. What are the turns on some of the old Fender pickups?
Pickup    Wire Gauge   Turns (old)   Turns (new)
1000 PEDAL STEEL    42 HF   8,000   
12 STRING    42 PE   12,500   11,215
400 PEDAL STEEL    42 HF   8,000   
5 STRING BASS (OLD MODEL)    42 PE   12,000    
BASS VI (6 STRING)    42 HF   8,550   
DELUXE 6 LAP STEEL    42 HF   8,350 (PE)   7,600
DELUXE 8 LAP STEEL    42 HF    8,550   
DUAL 6 STEEL GUITAR    42 HF    8,350 (PE)   7,600
DUOSONIC (OLDER MODELS)    42 HF    8,350 (PE)   7,600
EARLY 50'S LAP STEEL    42 PE-43 PE    7,600    
ELECTRIC MANDOLIN    42 PE    8,000   
JAGUAR    42 HF    8,550   
JAZZ BASS    42 PE    9,000    8,000
JAZZMASTER    42 PE   8,500   
MUSIC MASTER BASS    42 PE    7,600   
MUSTANG    42 HF   7,600    7,600
MUSTANG BASS    42 PE    12,000   
PRECISION BASS    42 PE    10,000   
STARCASTER (HUMBUCKING)    42 Poly    6,400   
STRAT (LEAD II) X-1    42 Poly    9,600   
STRATOCASTER    42 HF    8,350 (PE)    7,600
STRINGMASTER STEEL GUITAR    42 HF    8,550 (PE)    7,800
TELECASTER BASS (HUMBUCKING)    42 Poly    14,750    14,500
TELECASTER BASS (SINGLE COIL)    42 PE    8,900   
TELECASTER DELUXE    42 Poly    6,400    
TELECASTER LEAD    42 PE    8,000    7,800
TELECASTER RHYTHM    43 PE    8,000    7,600


_________________
Scott Swartz
Steeltronics - Steel Guitar Pickups
www.steeltronics.com


Last edited by Scott Swartz on 16 Nov 2020 7:49 am; edited 2 times in total
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Jim Palenscar

 

From:
Oceanside, Calif, USA
Post  Posted 16 Nov 2020 7:47 am    
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Thanks Scott!
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Michael Brebes

 

From:
Northridge CA
Post  Posted 17 Nov 2020 6:57 am    
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In the last year, I rewound a trapezoid pickup on a Fender double neck. I remember that it did use 42 gauge wire and I put about 8000 turns on it, which closely matched how much wire I removed. It also closely matched the other pickup in resistance measurement, which is a good indicator that I did it correctly. In most pickups, Leo's go-to number of turns was about 8000. 10,000 is way too much. It was definitely a different pickup to disassemble and rewind.
_________________
Michael Brebes
Instrument/amp/ pickup repair
MSA D10 Classic/Rickenbacher B6/
Dickerson MOTS/Dobro D32 Hawaiian/
Goldtone Paul Beard Reso

Mesa Boogie Studio Pre/Hafler 3000
RP1/MPX100
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Jim Palenscar

 

From:
Oceanside, Calif, USA
Post  Posted 17 Nov 2020 8:27 am    
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Thanks Michael! I've done several in the past that have worked out well however they are a challenge. I usually have to repair the bobbins a bit and have made a Delrin insert where the strings go through to keep the bobbin from collapsing while winding.
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Scott Swartz


From:
St. Louis, MO
Post  Posted 19 Nov 2020 7:07 am    
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Heres another of Seymour's posts on these
Tab:

328. What kind of pickups are used on older Fender Lap Steels?
There were several types of pickups used on K & F and Fender lap steels. In Leo’s and “Doc” Kauffman’s early patent number 2,455,575 filed on September 26, 1944 and granted on December 7, 1948 there are several components. The bobbin consisted of a Vulcanized bobbin with 6 tubes in which the strings would go through without touching the walls of the cylinders. The pickup used two Alnico bar magnets and held in place by two fabricated case hardened steel shells and the bottom shell or case would support the string and guide it through the cylindrical tubes. The case hardening keeps the string from cutting into the edge of the material. The strings were actually through the center of the coil. The pickups looked rectangular from the top. The front side of the shells or casing are notched between each string to focus the magnet field to the strings. Each end of the pickup uses a sand cast Alnico magnet with the same polarity facing up on each end. Below are some winding specs for a few “Direct String Pickups” where the strings go through the pickup.
Fender Lap Steels that I’ve evaluated:
Lap Steel Model    Turns    Magnet Wire    Shape
K & F Lap Steels    7,522 Turns    42 PE    rectangular pickup
Organ Button Model    7,954 Turns    42 PE    rectangular pickup
Deluxe Model    7,633 Turns    42 PE    rectangular pickup
Dual Professional    7,855 Turns    42 PE    rectangular pickup
Custom Triple Neck   8,319 Turns    42 PE    Offset rectangular pickup
The Direct String Pickups use two Vulcanized fibre flatwork and often a clear vinyl plastic, computer cards or thin fibre board was used for the center of the bobbin. Spacers of wood or plastic was used to help keep the materials from warping over time. On the Custom Lap Steel pickups the coil had to be wound off center on the bobbin. The pickups were also wax potted to help eliminate unwanted feedback and added protection to the coil. A small piece of fibre or cardboard was usually placed over the eyelet’s so they didn’t short out with the metal case of the pickup.
Strings above the Pickup
Champion Lap Steel    7,633 Turns    43 PE    Telecaster style pickup
Stringmaster 8 String    8,535 Turns    42 PE    Similar to a Duosonic

Stringmaster 6 String    7,885 Turns    42 HF    Similar to a Duosonic
The Stringmaster pickup assembly used two pickups each wound and magnetized opposite of the other. The pickups are connected to a potentiometer to blend one pickup in and out for single to a dual humbucking sound. Over the years many Champion lap steel pickups were removed and modified to fit the bridge position on Telecasters.

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Scott Swartz
Steeltronics - Steel Guitar Pickups
www.steeltronics.com
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Jim Palenscar

 

From:
Oceanside, Calif, USA
Post  Posted 19 Nov 2020 7:34 am    
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Terrific- thanks Scott!
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Bill Flores

 

From:
Ventura, California, USA
Post  Posted 19 Nov 2020 9:06 pm     Fender Trapazoid
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Just a side note, many years ago I had Seymour Duncan rewind a very early trap pickup off my 1948 Dual 8... the center bobbin material was a time card!...
Bill
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Jim Palenscar

 

From:
Oceanside, Calif, USA
Post  Posted 19 Nov 2020 9:15 pm    
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Those things are tough to work with for sure. This 1950 guitar had a bobbin that looked like it would have been a lacquered time card. I make an insert where the strings go through to keep it from collapsing when I wind it b4 potting.
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Michael Brebes

 

From:
Northridge CA
Post  Posted 20 Nov 2020 1:44 pm    
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Mine was similar. Some kind of thick card stock that was formed and lacquered to the correct shape.
_________________
Michael Brebes
Instrument/amp/ pickup repair
MSA D10 Classic/Rickenbacher B6/
Dickerson MOTS/Dobro D32 Hawaiian/
Goldtone Paul Beard Reso

Mesa Boogie Studio Pre/Hafler 3000
RP1/MPX100
View user's profile Send private message Send e-mail


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