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Slide 88
12 Blinks Error Code (Sound)
The transistor Q2300 monitors the speaker amplifiers ICs (IC2301 and IC2302). Pin 3 of both ICs is
normally high. If any of these ICs or one of the speakers develops a short circuit, pin 3 goes low
causing Q2300 to go into conduction and output a low to the base of Q2300. As a result, Q2300 comes
on and outputs a high to pin 27 of the System CPU (IC1100) on the A board.