Bio-Rad CHEF-DR II System - Manual (Page 9)

Bio-Rad recommends that the buffer in the system be pre-cooled to the desired run
temperature. The Cooling Module can quickly pre-cool the system, at an approximate rate
of 0.75 °C/minute in the absence of input power to the recommended operating temperature
of 14 °C (to pre-cool from ambient temperature to 14 °C only takes 10–15 minutes), and is
designed to maintain set temperature during the run. If the buffer is not pre-cooled, the
presence of input power (from the electrophoresis power supply) will greatly increase the
time required to bring the system to the set temperature.
Note: The 0.75 °C/minute pre-cooling rate decreases for set temperatures lower than
14 °C.
Section 6
Troubleshooting Guide
Problem Solution
No power Check fuse in main power switch on back panel of unit (see
Section 7)
Fuse in main power switch OK; contact Bio-Rad instrument
service
Power on, compressor Reset timer
not running
Temperature set too high; lower setting
Still in 100 second delay period
No or low buffer flow Check tubing for kinks
Pump flow rate too low
Frozen buffer in heat exchanger; turn pump on; raise set tem-
perature above ambient until buffer flow resumes, then lower
set temperature to desired setting.
Insufficient cooling Pre-cool buffer to set temperature prior to beginning gel run
Buffer concentration too high
Buffer flow rate too high
Electrophoresis or buffer flow conditions outside design range
limits
Unusual noise Frozen buffer in heat exchanger; in variable speed pump see
or vibration above
Air leak from loose tubing connection
Small pool of liquid Frost may form on heat exchanger under certain operating
under Cooling Module conditions resulting in small amounts of water following
Cooling Module shutdown.
6