10 TEGAM WAY • GENEVA, OHIO 44041 • 440-466-6100 • FAX 440-466-6110 • sales@tegam.com
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TROUBLESHOOTING
The TEGAM Model 1750 has been designed to provide many years of trouble free performance.
However, there are some instances where harsh operating environments or excessive physical strain
may cause premature failure. Should a malfunction of the 1750 be discovered, it is recommended
that certain steps be taken in order to assist our service department in identifying the cause of the
malfunction and to provide the quickest possible turn around time for the repair cycle. Below is a
summary of some commonly observed symptoms and some possible causes for them. These should
be checked before sending the 1750 unit to TEGAM for repair.
No Display – The display is completely blank:
• Check the power supply. Make sure that the AC line is supplying power to the unit.
• Check the fuse located in the rear panel. If a blown fuse is identified, there is usually a reason for
the fuse blowing, so the probability of another related problem is high. Send the unit in for service.
Reading Drifts – An accurate reading may be obtained but its value over a short period of time
begins to climb or drop at a slow but noticeable rate.
• This is usually a sign of heating. It is very possible that the resistance of the test component is
changing due to the 1750 test current. The resistance may drift upward or downward depending
upon the temperature coefficient of the test component. Try testing at a lower current level or
using a one shot trigger mode in order to reduce the amount of power being sent into the test
component.
• Check the cooling fan operation to make sure that it is moving freely and there is no excessive
bearing noise. Make sure the fan filter is clean and that air can move freely through the filter.
Unstable Reading – The reading bounces erratically with no apparent pattern. Depending on the
measurement range and trigger mode, there is a certain allowable error for counts usually 2-5 counts.
(See Section 1 for the exact specifications). Readings that bounce out of the specification ranges
usually indicate a problem with noise.
• Make sure that the test leads or fixtures are manufactured by TEGAM. All accessories for the 1750
are specially designed to minimize the effects of external noise to the measurement signal.
• Check the Line Frequency option to make sure that the correct frequency is selected. The 1750
uses a special algorithm to eliminate noise created by line power.
• Verify that there are no sources of noise in close proximity to the 1750, test leads, power leads,
or test fixture. The 1750 performs measurement in the nanovolt range and sources of noise such
as CRTs, relays, and other switching devices are primary causes for erratic readings.
• Make sure that adequate settling time is permitted in order to receive a reading. Sometimes it
takes time for the measurement to stabilize before data is read by the A/D.
• Make sure that the device being tested is not highly inductive. In some cases when involving
motors, transformers, or excessive lengths of wire, the switching action of the test signal does not
function well with high inductance. If there is an issue with a particular application, please call
TEGAM and ask to speak with one of our applications engineers.
PREPARATION FOR CALIBRATION OR REPAIR SERVICE
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