Hahahaha tres ingénieuse!
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Quote from: sean on November 23, 2010, 01:15:42 PM
EK-10 service manual: http://www.fenderrhodes.com/pdf/mark3-service-manual.pdf
According to the EK-10 service manual, they put shields between the pickups. You can see them in the photos you linked.
I assume this was to prevent the adjacent pickups from generating enough signal to trigger ghost notes from the electronic voices.
The first page of the manual tells how the signals from the pickups were grouped into the ribbon cables:
Ribbon cable 1 carries signals from all E's and Fs.
Ribbon cable 2 carries signals from all F#'s and G's.
Ribbon cable 3 carries signals from all G#'s and A's.
Ribbon cable 4 carries signals from all A#'s and B's.
Ribbon cable 5 carries signals from all C's and C#'s.
Ribbon cable 6 carries signals from all D's and D#'s.
There is a paragraph on page 11 that describes how the individual pickup signals are routed: "The signal is sent through mixing resistors R4[01-12] to [transistor] Q4 or Q5. The amplified signal is sent [via ribbon cable connector C/P2] to the op amps on the mixer on the namerail." On the mixer PCB that is on the namerail, the sound from the pickups is sent through [op amp] U3A/B (page 17). (Then on page 12... "The signal from each of the pickups is also sent to an active rectifier and amplifier..." to create the envelope for the electronic voices.)
The result of all this means that each individual pickup is connected individually. Dead pickups do not affect any other note.
Remarkably, I think this setup is still humbucking! If you look at the schematic on page 24, the pickup signal that is coming in to connector P1 on pin 7 and pin 1 are from adjacent pickups. As long as these two pickups are wired with one hot signal from the front and the other hot signal from the back, you will get EMI noise cancellation.
If you look the second photo, you will notice that the purple and grey wires feeding the ribbon connector come from adjacent pickups (the fourth and fifth pickups from the right in the photo). These two pickups are indeed wired with opposite polarity! Cool.
Here is the photo again:
Quote...Listen to Harold Rhodes share a bit of Rhodes history in his own words, reminiscing about the Fender Rhodes mobile piano teaching lab and reflecting on personal experience and philosophy behind his piano teaching method.
*These Major Key series of recordings are from John McLaren Jr.'s private collection. Unauthorized duplication or distribution is strictly prohibited. Copyright 2010 Major Key©.