Section 4: Theory of Operation
4.3 FPS Theory of Operation
0101-8242-0, Rev. C
4-5
CV-6SLX User Manual
Figure 4-3 Filament Power Supply (FPS) Module
Figures 4-4 and 4-6 show the locations of the major components in the standard FPS unit (i.e.,
with PN 0620-6604-0) and for FPS units with PN 0620-6604-2, respectively. Figures 4-5 and 4-7
are top-level block diagrams for the same units. Primary power enters the FPS via J302 and is
routed to the Filament Supply PCB. The FPS consists of two major functional sections, the
Filament Supply PCB and the Filament Output section. The Filament Supply Board supplies and
controls the filament power. The filament output section combines the filament power with the
negative HV from the power module and routes the combination to the filament. As Figure 4-5
shows, the Filament Output section on standard FPS units consists of an HV vacuum relay and a
filament transformer. On FPS units with PN 0620-6604-2, the Filament Output section consists
only of a filament transformer (see Figure 4-7). Section 4.3.4 describes the Filament output
section in greater detail.
4.3.2 Safety Interlocks
The safety interlocks insure that circuits are safely connected and that the box is closed before
operation can continue. Safety interlocks are provided by switches S101 and S102 in the
filament output section of the FPS. These interlocks are routed to the Filament Supply PCB via
J103 pins 3 and 4 and are connected in series with the cover interlocks on the CV-6SLX power
module. Therefore, in order for FPS operation to take place, the FPS covers and the power
module covers must be in place, closing the interlock switches, and the FPS cover interlock
switches must be connected to the Filament Supply PCB.
