GE Corometrics 126, Руководство по обслуживанию

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Revision B 120 Series Maternal/Fetal Monitor 4-23
2015590-001
Theory of Operation: Main Motherboard
Recorder Interface Section
The recorder interface section consists of 7032 interface PAL (U38), recorder clock
and data buffers (U36), and clock divider 74HC4040 (U39). The interface PAL
contains latches to create the four strobe lines, load line, and stepper motor four
phases along with head protection circuitry which automatically shuts off all of the
strobes and the HDSHUT* line (turns head power supply off). The protection works
by enabling the external counter when a strobe line is turned on, and automatically
disabling the strobes (and enable HDSHUT*) lines after a 6.1 ms timeout. A buffer
is also present which allows the paper out (POUT*) and paper low (PLOW*) lines
to be read. Logic for the QUART reset line, ORs (in U38) the system reset with the
control latch reset to form a positive reset output to the QUART.
RS-232C Communications Section
This section provides the external and internal RS-232C functions. These ports
(J109, J110, J111) are driven from the 68302 processor. The J110 port only
supports TXD and RXD lines while J109 and J111 supports RTS and CTS as well.
The QUART (U2) drives three internal RS-232 ports (NBP, MSpO
2
, and FSpO
2
) as
well as one external port (SpO
2
).