Fender Trapezoid pickup

[Jim Palenscar]

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.

[Scott Swartz]

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.

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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

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[Jim Palenscar]

Thanks Scott!

[Michael Brebes]

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.

[Jim Palenscar]

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.

[Scott Swartz]

Heres another of Seymour's posts on these
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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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[Jim Palenscar]

Terrific- thanks Scott!

[Bill Flores]

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

[Jim Palenscar]

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.

[Michael Brebes]

Mine was similar. Some kind of thick card stock that was formed and lacquered to the correct shape.