Bio-Rad CHEF-DR® III Variable Angle System User Manual

Page 32

Problem

Solution

Large DNAs not resolved

1. Lower the voltage to below 2 V/cm
2. Increase switch time or use switch time ramp
3. Agarose impurities

High background in lanes

1. Insufficient washing of samples
2. Sample may be contaminated with RNA or other

material

3. DNA concentration too high

Distorted bands

1. Sample contains too high salt or detergent concentration
2. Buffer breakdown. Change every 48 hours.
3. Wells were distorted. Recast gel.
4. Sample plugs were crushed when placed in wells
5. Pump flow rate too low. Check for kink along tubing.
6. Not enough buffer in cell (total should be 2.2 liters)

Thick bands

1. Use thinner wells
2. Load less sample

Failure Codes

F-0

1. Error detected in the PS processor code during power

up. Contact Bio-Rad Laboratories

F-1

1. Error detected in the DAC processor code during power

up. Contact Bio-Rad Laboratories

F-2

1. The power supply control processor is not getting

adequate feedback from the high voltage power sup-
ply during a run. Normal operation will continue and
the display may be changed by pressing a display
mode key.
Check fuses and safety interlock

2. Contact Bio-Rad Laboratories

F-3

1. The DAC external RAM has been corrupted (all

parameters will reset to default values). Normal oper-
ation can be resumed by pressing any key on the right
control panel. The battery RAM on the DAC board
did not maintain its data when the power went down.
If this occurs consistently, there may be a hardware
problem on the board, or the battery may be bad.
Contact Bio-Rad Laboratories

F-4

If a gross overcurrent is detected (>500 mA), the sys-

tem is put into pause automatically and F-4 is dis-
played. When the problem is corrected, the run may
be resumed by pressing START.

2. Buffer concentration is too high. Remake the buffer

at the appropriate concentration.