CPI CMP 200 Series Service Manual page 285

7
Theory of Operation
7.2.2 DC bus & power distribution (Cont)
Refer to MD-083, sheet 4:
Sheet 4 applies to all units. For the membrane console, the +24 V supply is regulated to +5 V and -20 V
via F1 on the console board. The console board contains a 300 VAC (approximately) power supply that
drives the cold-cathode fluorescent lamp in the LCD display assembly. This power supply is driven from
the +5 VDC supply.
The touchscreen console is powered from the generator's +24 V supply; on-board regulators step this
down via F3 on the touch-screen board as required by the internal circuits.
Sheet 4 also shows the low-voltage DC power supply connections to the filament board and to the AEC
board.
7.2.3 Room interface (MD-0930)
+24 VDC, 120 VAC, or 240 VAC for the BUCKY DRIVE is available when K6 on the H.V. auxiliary board
is closed as described in 7.2.2. The 24 VAC and 24 VDC supplies are present at all times that the AC
mains is energized. The 24 VAC supply is fused by F11 and brought out at J11-6 and J11-5 on the H.V.
auxiliary board (maximum 150 watts for collimator use), and the 24 VDC supply is fused by F12 and
made available at J11-2 and J11-1 for system locks use (maximum 45 watts).
Bucky relays K1 and K3 on the H.V. auxiliary board are driven by U83 and U86 on the generator control
board. When K1 or K3 is energized, +24 VDC, 120 VAC, or 240 VAC is provided at J2-7 or J4-1 on the
H.V. auxiliary board to start Bucky 1 or Bucky 2.
The Bucky 1 or Bucky 2 ready signal (a contact closure is needed) will energize opto coupler U2 or U6
respectively. The Bucky-ready status from U2 / U6 is conveyed to the CPU via data buffer U89, where it is
processed to determine if the Buckys are ready to make an X-ray exposure.
During an X-ray exposure, the base of Q31 on the generator control board is pulled high via U19. This will
turn on Q31, energizing K7 on the H.V. auxiliary board. K7 provides a dry contact closure when
energized, which may be used to control the room light.
The H.V. auxiliary board also contains 4 interlock inputs. These include interlocks 1 and 2, the door
interlock, and the X-ray tube thermal switch interlock. Each of these interlock inputs requires a contact
closure to indicate a normal condition, with a closed interlock energizing the associated opto coupler U1,
U3, U4, or U9 respectively. The outputs of the opto-couplers are read by the CPU via data buffer U89 on
the generator control board, where the information is used to determine the readiness of the associated
input.
7.2.4 X-ray exposure (MD-0931)
Refer to MD-0931, sheet 1:
The PREP and X-RAY switches on the membrane console are connected in parallel with the console-
mounted hand switch, as shown on drawing MD-0931. The PREP and X-RAY switches on the
touchscreen console, the X-ray mini-console, and on their associated hand switches are connected to the
inputs of U8 and U9 on the generator control board, respectively.
Pressing PREP on the membrane console will energize opto coupler U9 on the console board. If U9 is
energized, or one of the PREP switches on the touchscreen console, X-ray mini-console, or on the
associated hand switch is pressed, U8 on the generator control board will be energized. The output of U9
on the console board is read by the console CPU, and the output of U8 on the generator control board is
read by the generator CPU via data buffer U71. A prep request will be recognized if the output of U9 on
the console board (membrane console only) and / or U8 on the generator control board is low. DS5 on
the generator control board will light to indicate that a prep request has been made.
Use and disclosure is subject to the restrictions on the title page of this CPI document.
Page 7-4
®
CMP 200 X-Ray Generator Service Manual
CPI Canada Inc.
Ch # 901476-09 Rev. C