Scale System (Optional for the Procedural, Electric, and Trauma Stretchers)
Chapter 3: Theory of Operation
The scale P.C. board communicates with the display P.C. board via connector
P11. It sends and receives signals using a SPI protocol. It also receives
regulated power (5 V DC) on pin 8 of this connector.
The Dip switches are tied in parallel to the red LEDs (DS1 to DS4). These
should always be in the off position.
There are 10 diagnostic LEDs on the P.C. board for service and
troubleshooting. They are separated into two categories: red for fault
conditions, and green to show correct operation. The LEDs are as follows:
• Load cell defective (RED; DS1, DS3, DS4, DS5) located by each load
beam connector will come on if a load beam cell is defective or if too little
or too much weight is applied to that load cell. Lifting up on a corner of the
stretcher will usually turn on one of these LEDs.
• CAN error (RED; DS9) shows that the CAN bus is defective. This LED
should never come on in a stretcher scale.
• Analog error (RED; DS11) shows that the analog voltage is in over-current
mode. Controlled by the TPS2020 OC line, this LED will blink until the
over-current condition is fixed (unplug the load beams one at a time until
the LED stays off).
• Watch dog reset (RED; DS2) shows a problem with the +5 V power supply
or a microprocessor issue. It is generated by the ADM706 RST/ line.
• Power LED (GRN; DS10), will come on if +5 V Primary Power is present.
• BAS LED (GRN; DS13), should never come on in a stretcher scale.
• ALARM LED (GRN; DS12), should never come on in a stretcher scale.
Display P.C. Board
The display P.C. board serves three main functions: to convert battery power to
a usable voltage for the scale P.C. board, the display, and itself; to convert
switch inputs from the user interface to serial data for the scale P.C. board; and
supply a pass through connection for communication with the display.
Power is supplied to the scale system by three AA alkaline batteries (connected
in series) which supply 4.5 volts nominally to the display P.C. board at
connector P4. A PTC (RT1) supplies over-current protection and MOSFET Q1
supplies reverse battery protection for the circuitry.
The switching regulator U10 and its surrounding circuitry take the battery
input and step it up to supply regulated 5 volt output to Vbr and VCC. This
supply powers the display P.C. board, the scale P.C. board, and the user
interface panel and circuitry (drawing from 15 to 50 mA). Starting from sleep
mode, regulator U10 is enabled through diode D30 by any switch closure.
3
Hill-Rom® Transport, Procedural, and Specialty Stretchers
Page 3 - 7
Service Manual (144386 REV 2)
Содержание P8000
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Страница 441: ...Schematic Wiring Diagram Control Board P N 49603 ...
Страница 442: ...Schematic Wiring Diagram Electric Stretcher P N 60389 ...
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