Welch Allyn 5102 - Symptom and Solutions; Scale Not Turning On; Inaccurate Weight Readings

14
Symptom and Solutions
Symptom
Possible
Cause
Corrective Action
Scale does not
turn on
Dead Batteries or
no rear Adapter
Replace Batteries (Alkaline “C” Cells)
Faceplate
Remove Front Panel. Check to make sure the Black and Red
cable connector is in place. Replace the switch assembly or
the Battery Holder Assembly.
Cracked Battery
Holder
Display
Board/Main
board
Replace the board
Inaccurate
Weights, Scale not
weighing
correctly, scale
broken, drifting
Load
Cell/Calibration
(OHM out Load Cells) See Calibration procedure this Service
Manual
Bad A/D Chip
Removing the top plate, the load cells will be visible
1. Enter into “Cal Mode” from the front panel
2. Press and hold the Reweigh button
3. Turn the Scale on
4. Release the Reweigh button immediately
5. Immediately go to the ST logo and press 5 X
6. Display should say “CAL”
7. Press ST Logo two more times to display A/D
Readings
Note: A/D reading without a load. Look for a low stable
weight reading less than 10 lbs and that is not drifting or
unstable.
Unplug each load cell and connect one at a time to see if
your display becomes unstable. This will tell you which load
cell needs to be replaced
Cold Solder on
the Calibration
Plug
Check Gain Resistor R24 on the Cal Chip, Replace Cal chip if
necessary.