Electronics International TC-1P - Manual (Page 18)

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3. Extension Cable Check Out Troubleshooting Suggestions
2. Probe Check Out:
There are two good methods of testing a probe. Perform one or both of the following:
A. A probe can be tested with an ohmmeter. Disconnect the probe from the Extension Cable. When
testing the resistance between the connectors, the probe should measure a “short” (less than 5 ohms).
When measuring from one lead (either lead) of the probe to the probe sheath (metal tip), there should be
an “open” (10k or greater).
B. Another method of checking a probe is to plug the suspected bad probe into a channel that is work-
ing properly. If the problem follows the probe, you have a defective probe.
3. Extension Cable Check Out:
With the Extension Cable connected to the unit, remove the probe from the suspected bad Extension Cable.
Set the unit to the proper channel and look for a near cabin temperature reading on the display. A very high
or low reading indicates a short to ground in the cable. Next, connect an ohmmeter, set to 10K range, to the
open probe ends of the suspected bad Extension Cable. Set the unit to the proper channel and look for a very
high (+ or -) reading on the digital display. A near cabin temperature reading or no change in reading
indicates an open in the cable or its connectors. Also, look for a reading on the ohmmeter around 12K ohms.
Most problems of this kind are usually one of the following:
A. Poor Connections: When plugging the probe into the extension cable it is possible to get the tab on
the male connector to wedge between the red nylon and metal receptacle in the female connector. This
connection may work for a few weeks or even months and then you will start to see jumpy readings.
Disturbing the connection, without actually fixing it, may get it to work for a short time and then the
problem will reappear. Physically check your connections at the probe for a proper mate.
B. Loose Connections: The female slip-on connector between the extension cable and probe can
become loose if the connector has been used many times. This loose connection may work for a few
weeks or even months and then you will start to see jumpy readings. A good connection is difficult to
pull apart. If your connector is loose it can be tightened using a pair of needle nose pliers. Check your
connectors at the probe for a good tight connection.
C. Poor Crimp: This is usually only a problem if you have removed the connectors and replaced them.
This connection may work for a few weeks or even months and then you will start to see jumpy read-
ings. To check a crimp, give a sharp pull on the wire and connector. The wire should be tight in the
crimp (no movement). When putting a new connector on a wire, double the wire over and put two tight
crimps on the connector.