Welch Allyn AudioScope, Service Manual

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1.6 Operating Program
of Models
23020, 23000, 23040
Single Hearing Level AudioScope
NOTE: Since these models of AudioScopes are well over ten years old, the circuitry
is no longer available. If this circuitry fails, the Single Level AudioScope is no
longer repairable. Recalibrations CAN be performed if the unit is functioning
properly. If the unit fails, however, the lamp, battery, and charging
stand/transformer can be re-used with the AudioScope3.
See Fig. 1-6 Block Diagram of Welch Allyn AudioScope.
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SINGLE HEARING LEVEL AudioScope models (20,25,40 dB) use the same
basic circuitry except for the value of R 21 and the adjustments on
VR2.
Model: Ohms of R21:
20 dB AudioScope = 11 Ohms
25 dB AudioScope = 20 Ohms
40 dB AudioScope = 130 Ohms
AudioScope Service Manual 1.6