Tegam 3550 - Troubleshooting

6-4
Model 3550 LCR Meter Instruction Manual Service Information
Troubleshooting:
The TEGAM Model 3550 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 3550 be observed, 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 remedies for
ruling out the possibilities of user error or environmentally-related problems.
No Display – The display is completely blank.
x Check the power supply. Make sure that the AC line is operational and is supplying power
to the unit.
x 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.
Unstable Reading – The reading bounces erratically with no apparent pattern.
Be sure that the Operating Instructions have been reviewed and thoroughly understood. Constant
voltage or constant current modes, sample averages, frequency and other settings can affect the
stability of the reading. Readings that bounce out of the specification ranges can also indicate a
problem with noise.
x Make sure that the test leads or fixtures are manufactured by TEGAM. All accessories for
the 3550 are specially designed to minimize the effects of external noise to the
measurement signal.
x Verify that there are no sources of noise in close proximity to the 3550, test leads, power
leads, or test fixture. Sources of noise such as CRTs, relays, and other switching devices
are primary causes for erratic readings.
Inaccurate Reading – Measurements do not fall within expected or known values or accuracies.
x Perform Open and Closed Circuit Zero Correction procedures as instructed in this manual.
x Make sure that the Range is appropriate for the measurement.
x Verify that four or five-wire Kelvin measurement leads are being used and that they are not
defective.
x Measured component values can sometimes vary with the test voltage or current being
applied. Make sure that the manufacturer’s recommended test settings are followed in
order to duplicate measurement results. Sometimes constant current or constant voltage
modes may be required to stabilize readings.
x Verify that the test fixture or leads is appropriate for the measurement to be performed.
Not all fixtures and leads are designed for the entire range of 3550 test frequencies and
measurement accuracies.