Bio-Rad CHEF Mapper® XA System - Manual (Page 7)

Accessories Included
Variable speed oscillating pump 120 V, ground isolated. Flow rate 1 liter/min, typical
Casting stand 14 cm x 13 cm
Comb 15 well comb and comb holder
Tygon tubing 365 cm
Disposable Sample plug mold 50 slot
Yeast DNA standard Saccharomyces cerevisiae YNN295
Chromosomal grade agarose 5 g
Pulsed field certified agarose 5 g
Leveling bubble
Manual
Cooling Module
Weight 14 kg
Construction Aluminum
Dimensions 42 cm long x 23 cm wide x 24 cm high
Cooling capacity 75 watts of input power at 14 °C
Operating range 5–25 °C
Fuse 100/120 V: 6.3 amp, 250 Slo-blo
220/240 V: 3.1 amp, 250 Slo-blo
Total system weight 41.7 kg
1.3 Description of Major Components
Power Module
The power module contains the electronics for pulsed field electrophoresis, including a
350 V power supply, the switching functions, and drivers for the 24 electrodes. The front
panel contains a two line fluorescent display, buttons, switches, jacks, and a fuse as described
in Section 4. The fused power supply operates with a maximum of 9 V/cm, or 350 V. The
lowest gradient is 0.6 V/cm, or 20 V. The drivers provide clamped homogeneous electric
fields in the chamber and maintain them regardless of the pulse angle selected. This feature,
dynamic regulation, regulates the potentials so that the proper voltages are maintained
regardless of gel size or fluctuations in buffer conductivity or temperature.
Figure 1.1A shows the relative potentials of each electrode pair when the + 60° vector
(indicated by the arrow) is activated. Net field vector is from NW to SE. The highest poten-
tials are along the SE segment of the hexagon. The potentials gradually decline along the
adjacent segments. The NW segment, directly opposite the SE, has 0 potential, represented in
the diagram as negative terminals. When the - 60° angle is activated, the pattern of electric
charges is as shown in Figure 1.1B. Together, the two pulses result in a 120° included pulse
angle. Other angles will result in similar relative electrode potentials. One such example is field
inversion, shown in Figure 1.2A and 1.2B. In this case, the charges are primarily at N and S.
The pulse angles are 180° and 0°. Appropriately scaled voltages are along the sides of the
hexagon to achieve clamping.
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