Tension Sensor Pwa - Scully 280B Series Instruction And Maintenance Manual

AQdendum I, Model 280B
Constant Tension Feature
CONSTANT TENSION
1.1 GENERAL
1.2 The constant tension feature prevents changes in tape tension
against the heads caused by the varying amount of tape on the supply
reel or changes in tape speed. The tension sensor PWA, Figure 1, con­
sists of an opto coupler and an optical grating which control the
amount of light which reaches the transistor. The optical grating is
mechanically connected to the tension sensor dancer arm. As the
dancer arm moves in response to changes in tape tension, the tension
sensor PWA initiates changes in the holdback voltage applied to the
supply reel.
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Figure 1. Tension Sensor PWA
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