Kistler-Morse KM L-Cell Bolt-On - Manual (Page 79)

Appendix E. Troubleshooting
E-2
Small Amplitude
Changes or Erratic
Fluctuations in display
readings Small amplitude drift or
oscillation, with peak-to-
peak disturbance of 0.1% to
0.3% of full scale, is
normal. Reduce drift or oscillation by setting
‘count by’ and ‘averaging’ appropriately
on signal processor (refer to signal
processor manual).
Erratic fluctuations can be
caused by moisture in
cable conduit, junction
boxes, or junction box
PCBs.
Check conduit, junction boxes, and PCBs
for water contamination. Find water entry
source and correct problem. Dry with a
hair drier. Remove/replace corroded parts
and materials.
CAUTION
If using sealant to eliminate water entry,
use Sikaflex 1A polyurethane sealant or
Dow Corning RTV 739 or RTV 738. Other
sealants may contain acetic acid, which is
harmful to sensors and electronics.
Fluctuations can be
caused by damaged L-
Cell. Using Digital Multimeter (DMM), check
resistance for individual L-Cells:
1. Set meter resistance scale to accom-
modate measured range up to 20,000
ohms.
2. Remove one L-Cell ’s wires from
junction box terminal TB3.
3. Put one DMM lead on L-Cell’s white
wire and other lead on red wire. Record
resistance reading, and verify it is 4000±
200 ohms. If reading is outside this
range, L-Cell is damaged and must be
replaced.
4. Put one DMM lead on L-Cell’s white
wire and other lead on black wire. Record
resistance reading, and verify it is 4000±
200 ohms. If reading is outside this
range, L-Cell is damaged and must be
replaced.
5. Verify readings from Steps 3 and 4 are
within 200ohms of each other. If not,
L-Cell is damaged and must be replaced.
6. Repeat Steps 2 through 5 for each
suspect L-Cell, until damaged L-Cell is
located.
Problem Problem Details Solution