2-15. AUXILIARY RELAY CIRCUIT, CIRCUIT FUNCTION DESCRIPTION 9.3
Refer to figure 2-13. The auxiliary relay assembly allows for the selection, for
each ma station, of additional control functions not available from either the
ma-selection switch or the ma-selector-relay panel.
a. These functions are as follow.
Selection of the ma, time, and kvp adjustment pots.
(3) The PREPARE/EXPOSE signal source, to control the panel or
footswitch and ion chamber interlock.
Damping resistor selection.
b. On one set of contacts of each selection relay is MVD from the ma-time
kvp-overload assembly. The relay appropriate to the ma selection, R1 for 200L SPOT,
R2 for 25ma, etc., will be energized. The MVD will output on the selected MY lead back to
the ma-time kvp-overload assembly.
c. On a second set of contacts of each selection relay is XD from the filament
control. If R1 is energized and 200L SPOT selected, XD outputs on XRS1 to the
spot-film changeover, where the selection of XSU for the small focal spot of the
under-table X-ray tube in fluoro, or XLU for the large focal spot of the under-table X-ray
tube in radiographic, is accomplished.
d. Relays R2 through R4, select XSO for the small focal spot of the over-table
X-ray tube. Relays R5 through R8 select XLO for the large focal spot of the over-table
X-ray tube. On the third set of contacts of R1 is 115F to either CE normally closed
contact, or FE normally open contact. When R1 is off, and a ma selection other than
200L SPOT is made, the PREPARE/EXPOSE enable is to the PREPARE and EXPOSE
push buttons on the control panel. When R1 is energized, and 200L SPOT is selected,
the EXPOSE enable is to the footswitch.
e. The EFO safety signal is on the third set of contacts of R2 through R8. If any
one of these relays is energized, connection to ERO is through the normally open
contact of that relay. If none of these relays are energized, and R1 is selected, the
connection to ERS is through the common normally closed contacts of the relays in
series. This is the ion chamber selection safety when autotiming is selected.
f. On the fourth set of contacts is 24vac. A group of jumper-connection points
from the normally open contact of each relay to lead ADR is on the auxiliary relay panel.
If a jumper wire is installed, ADR will be at 24vac when that ma station is selected.
ADR operates the damper-resistor-shorting contactor.