Electrical System Operation; Power Board And Power Supply Operation; Power Board Connector Assignments - Bosch ACS 753 Repair Instructions

Electrical

ELECTRICAL SYSTEM OPERATION

The electrical system provides the various
voltage levels required for the machine to
operate effectively. The power board, power
supply, and control board work together to
condition the input voltage by removing voltage
spikes and noise, transforming the input
voltage to 12 VDC (power supply) for operating
relays and voltage regulators (power board),
to power the unit cooling fan, engage the
compressor and vacuum pump when required.
Inputs from the sensors and transducers are
processed (control board), to ultimately power
the manifold solenoids (power board) for
recovering, recycling, and recharging vehicle
A/C systems.

Power Board and Power Supply Operation

The Power Board is shown in Figure 3-1. The
Power Supply is shown in Figure 3-2. Refer to
these figures as needed.

Power Board Connector Assignments

See Figure 3-1, Power Board for connector
locations:
J1: Control Board J1
P1: Power Supply J2
P2: Control Board P19
P3: AC Input
P4: Power Supply J1
P5: Fan
P6: Vacuum Pump, Compressor
P4
P3
P6
K3
K4
P5
Figure 3-1. Power Board
SP00D00609 2018-03-26
P9
P8
J1
P7 P1
F1
K2
P2
58
ACS 753, ACS 763, ACS 863 Service Manual
P7: High-Pressure Switch
P8: Solenoids S1, S2, S3, S14, S15, S17
(is used on ACS 863 unit only), S19 and S20
P9: Solenoids S4, S5, S6, S7, S8, S9, S11,
S12, S13 and S22
The Power Board (PB) receives AC voltage at
PBP3 from the power switch and circuit breaker
to PBP3 pins:
• Pin 1 – Unit ground (on center divider)
• Pin 2 – AC low
• Pin 3 – AC high
The input voltage is immediately applied to
the Power Supply (PS) through PBP4 and
the interconnecting cable to PSJ1. The output
of the power supply is 12 V ± 0.1 VDC. This
is the main system control voltage and used
throughout the unit for its various functions
through PSJ2 to PBP1 and Control Board
(CB) receives 12 VDC from power board PBP2
through an interconnecting cable to CBP19
(See Control Board Functions). Relay K3 is
used to couple the 12 V output from the power
supply to the power board through PBP1.
Input AC voltage within the power board is
also routed to relays K2, K3, and K4. Relay
functions are:
• K2 – Fan
• K3 – Compressor
• K4 – Vacuum Pump
Power for the unit fan, vacuum pump, and
compressor is routed to those units through
PBP5 and PBP6 and wiring harnesses.
J1
Figure 3-2. 12 VDC Power Supply
1
J2
6
V Adj.
Robert Bosch GmbH