C-3
Power down the Analyzer. With the good sensor in
place, attach the “bad” sensor also. Power up the
Analyzer. After about 40 seconds, the READING SEN-
SORS message will appear. Measure the voltage on the
WHT wire of the “bad” sensor. Check the BLU wire also.
If the voltage is not changing, the sensor may not be
securely wired to the analyzer.
If the voltage is changing, the Analyzer is trying to com-
municate with the sensor. If the sensor is still not listed
as AVAILABLE, then there is probably something wrong
with the wiring or with the sensor.
1.4.3 After Start-up, measurement is incorrect.
See Online Problems.
1.5 ONLINE PROBLEMS
•
Measurement is incorrect
Conductivity
Troubleshooting:
1. Verify the sensor-ID number relationship
Change the process conditions at the sensor.
Does the reading change?
To change process conditions, try the following:
• Remove process liquid, or take sensor out of
process. Conductivity reading should go down.
Error message ELECTRODES OPEN should
become active.
• Short sensor electrodes with metal. Conductivity
reading should go up. Error message ELEC-
TRODES SHORTED should become active.
To Short Electrodes:
.01/cm - use a screwdriver (the stem - the tip may
scratch the electrode!), a paper clip, a penny, a ring.
1.0/cm - use a screwdriver, a paper clip.
.85/cm - use aluminum foil - inside of cigarette pack
or gum wrapper will work. Short the carbon elec-
trodes at the end of the probe.
Make sure the
white plastic shield is kept in place
- moving the
shield will change the cell constant.
Fix:
Troubleshooting often shows that the sensor wiring is
faulty. If so, correct the wiring problem.
If the customer is certain that the wiring is good, trying
resetting the analyzer by pressing the F1 and F3 keys
simultaneously during VIEW VERSION. The display
should begin the test pattern sequence to acknowledge
the keypress.
The customer will lose any analyzer settings that are
different from the Factory Settings.
The F1/F3 keypress loads data from program memory
into the EEPROM. This assures that analyzer configura-
tion data and sensor data is good.
•
Digital Output Not Communicating Properly
First, do MENU -> PROGRAM -> INSTRUMENT
ADDRESS
The default address is 01, but this must be “initial-
ized” by highlighting it and pressing ENTER. At this
point (after ENTER has been pressed, EXIT back to
the main screen.
Also make sure that the output is set to the same
type that is wired to on the back of the instrument.
For example, if the Non-Isolated RS485 is wired to
(Terminals 1 & 2 on TB3), then check MENU ->
OUTPUTS. Here, “RS485 NON-ISOLATED” should
be displayed. If it is not, choose INSTALL OPTION
CARD, highlight RS485 NON-ISOLATED, and press
ENTER. Then EXIT. Also try cycling the power at
this point; this will assure the change is accepted
via instrument re-initialization. If “ISOLATED RS485”
is chosen from the keypad instead, make sure
wiring is to TB1 (see proper section in this manual
for exact terminal designations).
The isolated RS485 card has an earth ground
“jumper” (small black plastic connector that ties
together two pins) located along one of the lower
edges of the circuit board. Make sure this is
removed.
If Isolated 485 communication is not working, check the
following:
1.
Wiring - RS485 D+ at OPT1 (TB1-6), RS485 D- at
OPT2. D+ was hooked to TB3-1.
2.
Option Board connection - verify that the 8 pins of
J1 on the option board are properly seated in J4 of
the RELAY board, and that the J2-J5 connection
also looks okay.
3.
If the Wiring and Option Board connection look
okay, try swapping option boards, if you have a
spare. Inspect J4 and J5 on the RELAY board to
see if any of the metal receptacles in the sockets
are bent or missing.
4.
Signals
The 485 signals are on the RELAY board - CPU
board connection (P7 - J3). The connection has two
rows of pins, with 20 pins total.
MODEL 2700
APPENDIX C
TROUBLESHOOTING GUIDE
Summary of Contents for 2700
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