Welch Allyn AudioScope, Руководство по обслуживанию

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1.7b Operating Program:
23300 (Microcontroller type serial
no.9670000 and higher)
(continued)
Multi-Level AudioScope3
(Microcontroller/non ASIC)
Sequence : Cause: Effect:
7. Logic U4 pin 6 goes to 3 V activates 4000 Hz LED (D6)
U4 pulses pin 4 U4 ramps U5 (digital pot) to calibrated
level. This establishes feedback
resistance for U3C.
U4 sequentially toggles pin Generates digital base amplitude
19, 20, 21, 22 sinewave at pin TP10
8. Logic
U4 pin 5 goes to 3 V activates 500 Hz LED (D7)
U4 pulses pin 4 U4 ramps U5 (digital pot) to calibrated
level. This establishes feedback
resistance for U3C.
U4 sequentially toggles pin Generates digital base amplitude
19, 20, 21, 22 sinewave at pin TP10
9. Logic
cycle completes itself and
activates
D2 Ready LED illuminates
10. Manual switch off
unit deactivates, lamps & logic off