Rice Lake Lift Truck/Pallet Jack Scales - Intercomp PW800 - Manual (Page 18)

PW800, Users
Rev O, January, 2008
18
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 probably is 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 88 8.8 88 8. 8 88 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 not 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.
Problem: rechargeable battery life has decreased
Fix:
The rechargeable batteries provided by Intercomp are high quality, high capacity Ni-
Cad. However, all Ni-Cad batteries can exhibit some “memory” effects if they are
repeatedly discharged to a certain point before recharging. If your observed battery life
has decreased significantly from its initial performance, you may want to try this battery-
conditioning sequence: Fully discharge the batteries by running the PW800 until the
display blinks “LB
LB LB LB” (low battery) and keep the unit powered until the batteries are fully
discharged. Following this, recharge the battery completely (typical charge time is 16
hours). This discharge/recharge cycle may need to be repeated. If this does not help,
you may need to replace the Ni-Cad batteries.
Problem: scale shuts off by itself
Fix:
Check the battery holder terminals. They may be bent and not making solid contact. If
the scale turns off immediately after you take your finger off the button, there may be
defective power circuitry or a bad keypad.