Archive for April 30, 2019

Teardown and Repair of an Agilent E4433B ESG-D 4.0GHz Synthesized Signal Generator (May 2019)

In this episode Shahriar takes a close look at a faulty Agilent E4433B 4.0GHz signal generator and vector modulator. This instrument is equipped with many of the most useful options such as dual arbitrary waveform generator and high-power output.

The instrument does not generate any error messages, however the output signal is ~20dB below specifications. After presenting the system block diagram and observing the output power characteristics, it becomes clear that the issue is with the mechanical attenuator. The teardown of the attenuator reveals faulty o-rings on the 5dB attenuation pad which has to be repaired with some flexible epoxy.

After the repair the instrument’s functionality is verified by measuring the output power with a power meter, frequency accuracy with a Rubidium frequency counter and the modulation accuracy with a vector signal analyzer.

Hitachi/Metabo electric can be purchased here.

Teardown, Repair & Experiments with an Agilent N4901B 13.5Gb/s Bit Error Rate Tester BERT

In this episode Shahriar repairs a non-functional N4901B 13.5Gb/s BERT mainframe. This instrument is equipped with both the generator and analyzer modules which makes it fairly valuable. The instrument does not power on and does not react to the soft power button.

Teardown of the unit reveals a TD-Lambda Vega power supplies series which is a fully configurable switching power supply design. Even though the power supply in the instrument is completely custom, it is made from generic sub-blocks readily available on eBay. A replacement front-end is purchased to repair the power supply after detecting the problem.

The instrument also shows a minor problem with falsely detecting an overload condition on the delay control port which is by passed by installing an overwrite switch. The instrument performance is verified by generating and measuring various eye diagrams through a back-plane PCB board.

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