Kurzweil K2000 Service Manual page 99

SECTION 5
AUDPWR2.DOC 12/15/92
5.1.2.8 RESET CIRCUIT
The reset circuit provides a power-up delay between sufficient power for operation and release of
the RESET signal to the microprocessors. Also, at power-down (or severe line voltage dip), this
circuit re-asserts RESET when the +5VDCdig regulator drops out of regulation. The reset circuit
consists primarily of U6l (H-3). It is wired as a high impedance schmidt trigger and gives a
fast rise and fall time signal to the microprocessors. Feedback through R156 (H-3) latches the
circuit in either the high or low state. Current through R155 overrides the feedback current and
forces the latch to flip. The last stage (U6l-8) enables both active-high RESET and active-low
RESETb.
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