Wurlitzer 930 tone cabinet
The 930 tone cabinet was intended for use with 140-series Wurlitzer electronic pianos. Although information on the 930 is scarce, it appears that it does not contain tremolo. Like the 920, it seems that the input of the 930 was to be taken from the electronic piano’s headphone jack; because all 140-series pianos had vibrato, 930 vibrato would have been redundant. Instead, it seems to have primarily provided additional amplification through four 4 ohm speakers in series-parallel arrangement.
In contrast to the 920’s tube amplifier, the 930 contains a solid state amplifier that has a strong resemblance to the amp circuit in the 140 and 140B. Like the 140/140B, the 930 uses two TO-3 output transistors driven by two separate windings of an interstage transformer. The 930 may also use the same power transformer as the 140 or 140B.
In the 930 schematic, the power transformer is depicted with two secondary windings—one for the main power supply, and one marked “NOT USED”. Solid state 140-series amplifiers also use an amplifier with two secondary windings. The first is a relatively low-voltage winding for the main power supply, and a the second is the high-voltage reed bar supply. The high-voltage supply uses a half-wave rectifier, so one secondary lead is grounded; the 930 schematic shows that the unused winding has the same lead grounded.
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930 AUXILIARY AMPLIFIER
FOR ELECTORNIC PIANOSPECIFICATIONS
TBD
TECHNOLOGY
Discrete transistors
SPEAKERS
TBDFEATURES
Auxiliary amplification for 140-series instrumentsModel 930 amplifier test
Serial no.: 690
Date: June 18, 1964
Spirit duplicationPart no.: 504049
Part name: Cleat top & bottom
Model: 930
Date: February 6 1964
Diazo printPart no.: 504053
Part name: Cleat short
Model: 930
Date: February 7 1964
Diazo printPart no.: 504060
Part name: Cleat - amp bottom
Model: 930
Date: February 7 1964
Diazo printPart no.: 504061
Part name: Grill cloth
Model: 930
Date: February 7 1964
Diazo printPart no.: 504063
Part name: Screen
Model: 930
Date: February 7 1964
Diazo printPart no.: 504064
Part name: Screen - back - bottom
Model: 930
Date: February 7 1964
Diazo printPart no.: 504072
Part name: Slide - support
Model: 930
Date: February 14 1964
Diazo printPart no.: 504073
Part name: End
Model: 930
Date: February 17 1964
Diazo printPart no.: 504083
Part name: Shipping block
Model: 930
Date: February 27 1964
Diazo printPart no.: 504138
Part name: Decal - Wurlitzer
Model: 930
Date: March 18 1969
Diazo printPart no.: 504204
Part name: Rubber stamp
Model: 930
Date: June 12 1964
Diazo print
