Rice Lake Intercomp CS 750 - Users Manual - Manual (Page 19)

CS750, Users
Rev R, May 2009
Page 19 of 27
Troubleshooting
WARNING : Changing some parts on the circuit board may cause a large
change in calibration while others may or may not change the calibration,
depending on the nature of the problem.
The reference designators for the IC chips are on the “A/D 20-BIT” board unless
indicated otherwise.
Problem: no power, nothing on display
Fix:
If nothing can be seen on the display, there is probably no power reaching the
scale circuitry. Possible causes: bad or shorted battery pack, bad switch circuit,
bad voltage regulator, or bad keypad. Power might be reaching the unit, but the
power supply might be shorted by a component or PCB trace in the power
supply circuitry.
Problem: random display (display usually reads “8.8. 8.”)
Fix:
Check crystal (Y1). If the micro-controller is not receiving the correct or any
oscillation, the microprocessor is not able to function properly. Other possibilities
could be bad microprocessor (U1) or display driver (U1 & U2 on “GPI DISPLAY”
board) circuitry not functioning.
Problem: low battery indicator won’t turn off (display blinks “LB LB LB LB”)
Fix:
The display will be blinking “LB
LB LB LB”. Check to make sure battery power is too low.
Look at the cells and charger circuit for these problems. If that is not the cause,
the display driver (U1 & U2 on the GPI display board) or low voltage circuitry
could be bad.