76 310531
Appendix C. Changing the Software Chips
Control Component Identification
There are four major control components:
Power Supply
Service Control Board
Current/Temperature Board
Pendant
Before you troubleshoot the PrecisionFlo Control, it is
important to understand what the control components
are and what they do.
Power Supply – See the electrical diagram in the
system binder
The power supply consists of several transformers that
convert the 110 or 220 Vac power supplied to the
system into four different dc voltages (+24,+5, +12,
and –12). These dc voltages are required for the
system to operate.
Service Control Board
The service control board does all of the math. It
monitors the regulator pressure and sends signals to
the motor control. It retains the set points in memory,
and sounds an alarm if a problem occurs.
The service control board holds five major integrated
circuit chips: two PrecisionFlo program chips (U6 and
U7), one micro-control chip (U4), one static ram chip
(U9), and a CPU chip (U1).
The service control board can only accept and send
out signals that are no greater than +5 Vdc.
Current/Temperature Board
The current/temperature board provides voltage isola-
tion and signal conditioning for the current and temper-
ature signals that the PrecisionFlo motor sends to the
control board.
Pendant
The pendant hooks directly to the PrecisionFlo com-
puter and communicates with it through RS–232
communication.
The function of the pendant is similar to the function of
a computer keyboard and monitor. The pendant allows
the operator to see information about the PrecisionFlo
operation and to make changes to the operation.
Checking for Control Panel DC Voltage
Problems
WARNING
ELECTRIC SHOCK HAZARD
High voltage is present when performing
the following voltage checks, which
could cause an electric shock injury if
the work is not performed properly. Do
not service this equipment unless you are trained
and qualified.
NOTE:
If any of the voltages are not present while follow-
ing steps 1 to 5 below, find the problem and fix it
before continuing to troubleshoot.
If the correct voltages are present and the software
is installed correctly, replace the control board if the
problem continues. The control board cannot be
repaired, it must be replaced.
1.
Verify that all dc common terminals are connected
together.
2.
Verify that the main power switch on the front of
the PrecisionFlo enclosure is on. Check all of the
dc voltages on the power supply outputs. There
should be +5, +12, –12, and +24 Vdc. See your
system binder for the wire numbers.
3.
Verify that the correct dc voltages are going to the
control board. There should be +5, +12, and –12
Vdc. See your system binder for the wire numbers.
4.
Verify that the correct dc voltage is going to the
current/temperature board. It should be +5 Vdc.
See your system binder for the wire numbers.
5.
Verify that the dc voltages are on all other dc ter-
minals inside the control panel. See your system
binder for the terminal numbers.
