9600 Service Manual - gmecorp-usa.com

Power Distribution 7
POWER CONTROL PCB
S/N 69-0001 thru 69-1000 - Assy. #00-876549 - Sch. #00-876547
The Power Control PCB is located in the bottom of the Workstation on the left hand side
as shown in Figure 2. Access is gained by removing the left side panel and a clear
plastic, protective shield.
AC1 and AC2 from the T1 isolation transformer enters at P1 and is used by both the
Workstation and C-Arm. See Figure 4 for details of the isolation transformer windings.
A +12 VDC is created on this board using AC1 through circuit breaker CB1, transformer
T1, bridge CR1, and voltage regulator U1. This +12V is sent to the keyswitch on the
front of the Workstation, to K3 and K4 relays on the Power Control PCB, and to the
delay circuit, U2.
When the keyswitch is closed, the +12V (Key_Pwr) is sent to K10 on the Power/Motor
Relay PCB located within the C-Arm. This switches Phase 1 AC to Power Supplies PS1
(+5V, +15V, -15V) and PS2 (+24V) also located within the C-Arm. The +12V is also sent
to activate K1 and K2 on the Power Control PCB. K1 connects AC1 and AC2 to the
Workstation. K2 connects +24V from PS4 to the left and right monitors.
POWER-ON DELAY CIRCUIT
The purpose of the delay circuit is to remove AC from the interconnect cable if it is not
plugged into the C-Arm and the Workstation is plugged into the AC wall socket. K3 and
K4 relays connect AC1 and AC2 from the Workstation to the C-Arm via the interconnect
cable. These two relays are turned on by +12V from U1. This occurs whenever the
Workstation is plugged into an AC outlet and the interconnect cable is plugged into the
C-Arm. This facilitates charging the batteries when the system electronics are switched
off.
The return paths for the coils of K3 and K4 are controlled by the U2 delay circuit. The U2
delay circuit is controlled by connections from the interconnect cable.
When the interconnect cable is connected to the C-Arm and the Workstation is plugged
into a wall outlet, the CNCT ON line is grounded on the C-Arm at the Power/Motor Relay
PCB. This forces U2-1 on the Power Control PCB to a logic low. Resistor R2 and
capacitor C3 charge to a logic high in approximately 540 mS. This high is placed on U2-
2 and is then cascaded through the rest of the transistor array finally placing a low on
U2-13 and U2-12. This low is fed through LOOP2 to the C-Arm and back to the Power
Control PCB through LOOP1, resulting in a low on K3-8 and K4-8. With the +12 V
output of regulator U1 on K3-1 and K4-1 both of these relays are then energized.
If the interconnect cable is disconnected from the C-Arm while the Workstation remains
connected to a wall receptacle, the CNCT ON line is no longer grounded through the
interconnect cable. This causes R5 and R1 to pull up U2-1 to a logic high. This, in turn
causes the following logic pattern to occur: pin 16 low, pin 15 high, pin 14 low, and pins