Bio-Rad BioLogic LP System - Manual (Page 98)

Gradient not as expected.
1. Check that the buffers are prepared properly, and the correct method has been selected.
2. Check the range setting on Gradient Monitor.
3. Check switch settings and connections of Chart Recorder. All switches should be set to position labeled
in green, and the conductivity signal cable (banana plugs) must be plugged into channel 2.
4. Measure actual flow rate through buffer “A” port with stopwatch and graduated cylinder, and compare to
actual flow rate. If the difference between indicated and actual flow rates is significant:
a. Check for worn tubing and improper platen adjustment;
b. Check for obstructed tubing, fittings, columns, or valves. You may wish to clean the system as
described in section 6.3, Flushing/Cleaning Valves, Flow Cells, and Filters.
5. Measure actual flow rate through buffer “B” port with stopwatch and graduated cylinder, and compare to
actual flow rate through “A” port. If the actual flow rates differ significantly, check for obstructions in the
proportioning valve or in the tubing leading to the valve.
Error Messages.
Under certain abnormal circumstances, the BioLogic LP may display an error message. The format of the
error message is:
BioLogic LP Error Trap!
<Text>
<Text>
Cycle system power to restart.
If an error message is seen, turn power “off”, wait 15 seconds, then turn power “on”. Turning the power off
will not lose methods or calibration values. If the message reappears, write down the exact text displayed,
and then contact your local Bio-Rad representative. (In the U.S., call 1-800-4-BIORAD for technical assis-
tance.)
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Maintenance and Troubleshooting