YSI 6500 Environmental Process Monitor - Manual (Page 60)

Troubleshooting Section 6
Possible Cause and Suggested Action: The individual pH and conductivity sensors (not just the sonde
guard) may have been extensively fouled with debris. Remove the sonde from the stream. Clean the
pH glass and reference electrodes by carefully wiping with moist lens cleaning tissue and then rinse
with clean water. Clean out the conductivity sensor ports with the brush supplied with the 6-Series
Sonde and then rinse with clean water. Inspect the dissolved oxygen probe face. If the membrane is
torn or shows any indications of punctures, replace the membrane. If either or both of the silver
electrodes shows heavy darkening, resurface the probe prior to installing the new membrane.
Detailed maintenance instructions for the sensors are found in Section 2, Sondes, of the 6-Series
Sonde Operation Manual. After cleaning, recalibrate the sensors and redeploy the sonde. If readings
still appear to be unusual, contact authorized service for advice.
6.5 ALARM FUNCTION PROBLEMS
Symptom: The alarm device wired to your 6500 does not appear to
trigger under the conditions that you have set up.
Possible Cause and Suggested Action: The problem may be due to a failure of your alarm device,
(e.g., a burnt out light bulb), or could be associated with a malfunction of the 6500 Monitor circuitry.
First, detach your alarm indicator from the 6500 and apply direct power to it. If it does not function
properly, repair or replace it.
If the device shows no malfunction, reattach it to the 6500 alarm circuit. Next activate the Main
menu of the 6500 by pressing the Esc and Enter keys simultaneously for 1 second. Highlight the
“Relays” selection and then the “Test Relays” selection. Highlight the relay in question and toggle
the relay “on” using the Enter key. When the relay is artificially activated, a check mark will appear
in the box and the relay indicator will spin, as shown in the display below for Relay 1.
If the above test is positive, the alarm (light, siren, etc.) should activate if the 6500 Monitor is
functioning properly. If no activation occurs, contact customer service for advice. If the alarm does
activate, press Esc to return to the “Relays” menu, then highlight the “Configure” relays selection and
press Enter.
Make certain that your relay is configured to activate under your desired condition. For example, you
may have selected > rather than < by mistake. If the condition for activation appears to be correct,
you may wish to induce an actual sensor condition under which the alarm should activate. For
example, if your relay is set to activate when the pH is less than 6.5, you can remove the sonde from
the stream and place the probes in pH 4 buffer. Return to the Run display for this test by pressing Esc
until the actual sensor readings appears on the screen. View the readings on the display to make
certain that the pH is close to the correct value (pH 4) and is indeed less than 7. If the alarm does not
activate under the induced condition, contact authorized service for advice.
YSI Incorporated 6500 Environmental Process Monitor 57