Troubleshooting - Turbidimeter Model 850
Download print version of troubleshooting information
| Problem | Possible Cause | Check/Remedy |
| No response/meter reading blank | • No power • Blown fuse • Faulty sensor bulb |
• Check power light. • Check fuse. • Check to see if sensor lamp is on. If lamp is off, check voltage across terminals 5 & 6 in sensor. If voltage is greater than 7 VDC, then sensor has failed. |
| Meter will not zero (high reading) | • Too much scattered light • Too much ambient light or too much reflected light • Poor sensor connections or incorrect wiring • Sensor leads not insulated from body of sensor or conduit • Wet connection in converter or sensor housings • Defective sensor/transmitter |
• Remove sensor and place in clean
water with a cover to shield
ambient light. • Disconnect wires on terminals 5 & 6. If meter still will not zero then ambient light is entering pipe. If meter will zero then too much reflected light. Try repositioning the sensor to reduce reflection. • Check connections and wiring. • Check sensor wires. • Look for water or condensate on connections. • Remove all sensor wires at transmitter. If meter will not zero turn span full counter clockwise. If meter still will not zero transmitter is bad. If meter will zero then sensor possibly has failed. |
| Unstable reading | • Air bubbles or very large particles
in process line • RFI pickup • Heavy Inductive loads |
• Take sample and check for bubbles
or large particles. If present
relocate sensor. • Earth ground instrument properly. • Mount instrument away from power cables. Put cables in conduit. |
| Reading does not agree with lab results | • Improper calibration • Lab procedure error • Lab instrument error • Defective sensor |
• Recalibrate instrument. • Check procedure. • Check instrument. • Refer to supplier. |
| Readings drift with time | • Converter not warmed up • Sensor/converter connections wet • Deposit buildup on sensor |
• Warm up converter for 15 minutes.
• Look for water or condensate on connections. Dry connections with hair dryer. Then use NEMA 4X enclosure. • Remove sensor and clean. |
| Negative readings or negative output | • Wet or damp connections • Faulty sensor bulb |
• Dry connections with hair dryer.
Then use NEMA 4X enclosure.
• Check to see if sensor lamp is on. If lamp is off, check voltage across terminals 5 & 6 in sensor. If voltage is greater than 7 VDC, then sensor has failed. |
