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3.3.3 System Controller Main PCB Coil Resistance Jumpers
Reliability of the MACS/D magnetic field compensation system is enhanced by limiting the Coil Driver Amplifier
(CDA) axial channel output voltages and currents to appropriate maximum levels for a range of possible coil
resistance values. This protection scheme is implemented within the MXA controller in the form of a jumper-
selectable option for each of the six output channels (XA, XB, YA, YB, ZA, and ZB—note that while only the “A”
outputs are currently used, the “B” outputs should be set identically). An array of 2-pin jumper headers for
selecting maximum MXA controller output voltage limits for each output channel are located to the rear of the Main
Printed Circuit Board (MPCB), as illustrated in
Figure 6
(SN≤ETS017) and
Figure 7
(current production), below.
Each channel’s output level selection scheme consists of two 2-pin jumper locations, with a “no jumper” option
(jumper stored on one pin only) creating 3 possible jumper-defined output limit settings per channel. However, the
“no jumper” option yields full-scale output levels of ±10.0V, and is used only for production testing or special
applications. Normal installations make use of one of the two jumper positions available for each channel: even-
numbered jumper positions for total axial coil set resistances of 12.5-20 ohms (amplifier bridged mode output
limited to approximately ±80V) and odd-numbered jumper positions for total axial coil set resistances of 8-12.5
ohms (amplifier bridged mode maximum output of ±56V). Systems are supplied with the MXA MPCB jumpers
inserted at the even-numbered headers for 12.5 ohm and up resistive loads. If operation with one or more coil
resistive loads less than 12.5 ohms is necessary, the appropriate jumper(s) can be accessed by first disconnecting
the system A.C. power source, removing the MXA controller from the rack cabinet, unfastening and lifting the
cover and modifying the jumper positions as necessary. Completely reassemble the rack cabinet assembly and all
harness connections prior to reconnecting A.C. mains power.
Figure 7. Coil Impedance Jumper Configuation for Units S/N: ETS018 and up (current production)
Note: View is from front of MXA Controller. Jumpers for default 12.5-20 ohm range are indicated by filled
in locations. Blank locations are 8-12.5 ohm range. Channel i.d.'s from left to right are: ZB (J19,20), ZA
(J17,18), YB (J15,16), YA (J13,14), XB (J11,12), XA (J9,10).
Figure 6. Coil Impedence Jumper Configuration for Units S/N: ETS001-ETS017 (previous MPCB
versions)
Note: View is from front of MXA Controller. Jumpers for default 12.5-20 ohm range are indicated by filled
in locations. Blank locations are 8-12.5 ohm range. Channel i.d.'s from left to right are: ZB (J19,20), ZA
(J17,18), YB (J15,16), YA (J13,14), XB (J11,12), XA (J9,10).
