The V303J Continental II Tone Generator - Overview

A Vox V303J Continental II or English "Super Continental" Organ Tone Generator Card

Expanding on the success of the V301J single manual Continental Organ, JMI started the development of the dual manual Continental II Organ in 1964. This new organ would include features that made it even more "Hammond" like than the single keyboard V301J Continental. You will read more about this on the V303J drawbar and bass clavier web pages.

Benefitting from previous engineering development at JMI, Vox V303J "Continental II" shared the same twelve small, solid state tone generator printed circuit cards that were used in the V301J "single" Continental. There were twelve tone generators in the V303J, one for each note of the musical scale. Each of these twelve cards was fitted with ten electrical contact pins that mated to a ten connector socket in the organ chassis and held in place by one screw.

Each of these twelve tone generator cards had a "master oscillator" and a six stage frequency "divider" circuit.

The master oscillator circuit used a pair of germanium transistors, several capacitors and a tuning coil. The master oscillator was the frequency tunable part of the circuit. The master oscillator also produces the organ's highest pitched tones. The pitch or frequency of the master oscillator is tunable by adjusting the tuning coil.

The output from the master oscillator is fed serially through six slave divider circuits. Each divider drops the input frequency in half or by one octave. Each of these six divider circuits had a pair of germanium transistors and a network of resistors and capacitors to accomplish this task. The output from the master oscillator and six serial dividers provided seven individual and discrete octaves of tones that would be combined and adjusted by the drawbar circuit of the organ, as done by Hammond.

When JMI first introduced the Continental Organ in 1962, germanium based transistors were the norm. Germanium transistors were not very dependable, as evidenced by anyone in the early 1960s that had a small transistor radio that failed. The germanium transistors were also prone to drift, causing both tuning and slave divider instability. For these reasons, Vox organs manufactured between 1962 and 1970 with germanium transistor based tone generator cards tended to visit the repair shop often.

The Continental II was known as the Super Continental in the U.S. Thomas Organ must have liked the word "Super," because thay also renamed the AC-100 guitar amplifier as the "Super Beatle."

In web pages to follow, I will explain the basics of V303J Super Continental Organ repair and adjustment so you can handle some of this maintainence yourself.


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Photos and editorial content courtesy Gary Hahlbeck, North Coast Music

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