Teardown, Repair & Experiments with a Voltech PM3000A 3-Phase Universal Power Analyzer

In this episode Shahriar investigates the failure of a Voltech PM3000A 3-Phase Universal Power Analyzer. This instrument is capable of advanced measurements on power profile and performance of a DUT. The unit shows “Voltage & Current OVERLOAD” condition on all channels even without a DUT connected.

The teardown of the unit reveals the isolation techniques used between the analog sampling heads and the main digital/DSP board. The instrument uses a combination of transformers and optocouplers to provide power to the sampling heads and receive digitized data from the voltage/current ADCs.

Close examination of the unit shows a faulty capacitor on the AC power supply feeding the sampling heads. The capacitor is replaced which corrects the overload condition. The unit is then used to measure the power profile of a simple glue-gun. The PF and THD measurements show that the glue-gun is equipped with a triac for power control; an expected result for a simple glue-gun.

One comment

  1. Mike Barg says:

    A visual inspection of the circuit boards revealed one leaking electrolytic capacitor. Replacing that cap turned out to be the sole cause of an otherwise working instrument to display an error. Applying sound root cause analysis solved the problem. Fortunately, there were no other serious issues in this case, but your logical troubleshooting process would have revealed them. Thank you for another excellent and instructive presentation, Dr. Shahramian!

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