Welch Allyn AudioScope, Руководство по обслуживанию

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1.6 Operating Program
:
23020, 23000, and 23040
Single Hearing Level AudioScope
Sequence : Cause: Effect:
1. Manual Switch "ON" Lamp "ON", Ready LED "ON"
2. Manual Press "START" U4 activated
3. Logic pin 11 goes to 0v activates LED (500 Hz LED.)
U4 pulls pin 20 to 0v selects resistance between pin
7 of U2 and ground.
this charges C5 produces 500 Hz sine wave at pin 2
of U2
U4 also selects resistance this resistance is adjusted for the
between pin 14 of U4 output amplitude of the 500 Hz tone
and pin 5 of U3. only and is used to control output
amplifier U3.
(Process repeats for the 1000 Hz, 2000 Hz, and 4000 Hz tones.)
4. Logic
pin 4 goes to 0v activates LED (1000 Hz LED.)
U4 pulls pin 22 to 0v selects resistance between pins
7 of U2 and ground.
this charges C5 produces 1000 Hz sine wave at pin 2
of U2
U4 also selects resistance this resistance is adjusted for the
between pin 15 of U4 output amplitude of the 1000 Hz tone
and pin 5 of U3. only and is used to control output
amplifier U3.
5. Logic
pin 12 goes to 0v activates LED (2000 Hz LED.)
U4 pulls pin 21 to 0v selects resistance between pin
7 of U2 and ground.
this charges C5 produces 2000 Hz sine wave at pin 2
of U2