Metex 2200P pH Analyzer/Controller - Manual (Page 30)

Model 2200P Page 28
9.0 TROUBLESHOOTING AND SERVICE
9.1 Calibration / Display Problem
9.1.1 If the problem is one of inability to calibrate or the display does not appear to match
the input, try the RESET feature. See Section 6.4. In rare cases, the ESCAPE
feature might be used. See Section 9.3.
9.2 Isolate the cause
9.2.1 When a measurement problem occurs, the first step is to try to isolate the cause. If
the 2200P is powered, go through the menu and check your settings. A convenient
way to do this is to call TEST. See Section 5.12
9.2.2 If your 2200P appears dead or intermittent, check the breaker, make sure that the
instrument is set up for the available line voltage and make sure the line voltage is
actually available at the terminals. Now measure that sufficient voltage is available
at all times; it should be 98 Vac to 132 Vac or 187 Vac to 243 Vac respectively.
Shut line power off, making sure it is off. CAUTION: Power to the relays may be
supplied from a separate source, shut it off too. Check and if necessary replace the
internal 0.25A fuse. Push the connector of the ribbon cable firmly into its socket. If
these steps do not solve the problem it may be necessary to replace the power
supply board. See Section 9.4 below.
9.2.3 Should your process control element e.g. pump, valve or alarm not be activating,
check that the correct power is supplied to the "floating” relay contacts, jumped over
from the line voltage terminals or perhaps from a separate breaker or DC supply.
Use the TEST menu feature to simulate the input values to observe the switching
points.
Check that your process control elements can function independently of the 2200P.
Next check with a test light or an Ohmmeter (power off to the relay contacts, wires
to the control elements disconnected) that the contacts of the respective relay are
making contact when actuated. If a relay is malfunctioning, it may be necessary to
change it. See Section 9.5.
9.2.4 If the process value seems wrong, clean the probe as described in the probe
manual. Inspect the probe, wire and interconnections. Open the inner door and
ensure that the two jumpers J42 are in the correct position for the probe used and
the probe wires are correctly and firmly connected. See Sections 3.5 and 3.6. Now
place the probe into a 7 pH buffer. Rinse, and place it into a 10 pH or 4 pH buffer
while observing the panel meter. If the values are close, re-calibrate and resume
operation. Should there be a major discrepancy, bring the probe and buffers to the
2200P, connect directly to the 2200P and repeat the procedure. If that does not
solve the problem, replace the probe.