Intelligent UFM-B Maintenance Manual page 19

5) Low Power Detection:
The Q2(A733) is designed to detect the power level. When battery
power is less than 5.5V, the collector pole will become low potential,
then CPU will instruct LCD display to show LO-BAT symbol.
3.2.1.2 Input voltage: 5.5V or higher
Check and recharge battery if voltage is less than 5.5V.
3.2.1.3 System voltage (Vcc): 5V +/- 10%
Check that the system voltage is within 5V +/- 10%
a) less than 4.5V, the CPU may not work properly.
b) more than 6V, ghosting will appear on LCD.
3.2.2 Platform Overload Stop
Make sure that the platform does not interfere with anything when
weighing. Check that the platform does not touch the upper (no
load) and/or lower (full load) overload stops.
3.2.3 LCD Display Checking
3.2.3.1 Check that it is soldered and connected properly between LCD
and driver IC (PCF8576), driver IC (PCF8576) and CPU.
3.2.3.2 Check whether LCD is broken.
3.2.4 CPU Checking
3.2.4.1 Check that all pins are seated properly into the socket.
3.2.4.2 Check that the Crystal Oscillator works.
3.2.4.3 Check the RESET is normally low.
3.2.5 A/D Unit Checking
3.2.5.1 Check that the A/D unit is correctly fed with +5VDC power.
3.2.5.2 Check that the signal output of loadcell is normal.
3.2.5.3 Check OP. Amplifiers & A/D Converter (AD7705).
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