Archive for December 17, 2017

Rohde & Schwarz RTB2004 10-Bit, 2.5GS/s MSO Oscilloscope Review, Teardown & Experiments

In this episode Shahriar reviews the Rohde & Shwarz RTB2004 10-Bit oscilloscope. With its high-resolution touch-screen, intuitive and capable GUI as well as excellent analog/digital performance this scope competes very well against other 2000 series instruments from Tektronix and Keysight. This extensive review includes instrument teardown, overview and dedicated experiments as follows:

01:17 – Model comparison and R&S scope lineup.
02:20 – Front panel, rear panel and overview.
05:01 – Instrument teardown and analysis.
13:37 – Power on and basic functions including intensity grading, XY mode.
26:29 – Multi-tone behavior, FFT and ADC performance.
33:17 – Experiment with ambient light follower: Analog and RS232 digital serial capture, triggering and analysis.
48:03 – Experiment with external DAC: Analog and I2C data capture and search using remote web interface.
57:19 – Built-in arbitrary waveform generator behavior and performance.

Teardown, Repair & Calibration of a BK Precision 9185 DC – 600V Linear Power Supply

In this episode Shahriar repairs a BK Precision 9185 600V linear power supply. The instrument is missing a power connector and therefore cannot be powered on. To be cautious, the unit is disassembled first before being retrofitted with a new connector. The teardown reveals damaged resistors at the back of the main power supply PCB. The damage points to a defective high-voltage MOSFET. This transistor is one of six devices in parallel. The impacted components are all replaced before the unit is retrofitted with a new power connector.

After power on the unit is verified for proper operation. Using a Keithley DMM7510, the power supply is calibrated and is ready for future experiments.

Teardown, Repair & Experiments with an Agilent 8562E 30Hz – 13.2GHz Spectrum Analyzer

In this episode Shahriar repairs an Agilent 8562E 13.2GHz spectrum analyzer which does not power on. Upon pressing the power button the power LED briefly flashes and turns off. Teardown of the unit reveals a compact instrument where the power supply is rather difficult to reach.

The power supply block diagram shows various internal block functions which include startup, DC-DC converter and output regulation stages. In order to diagnose the instrument, the CMOS driver ICs were removed and swamped. An error during the installation of the gate drivers caused a cascade failure of the supply components! After replacing all the affected components as well as the DC-DC converter PWM controller IC, the power supply is repaired.

After powering on the unit it becomes clear that there are several internal self-test and alignment errors. The errors point to YIG oscillator failure. The YIG oscillator no longer has the full range of frequency tuning. The core of the YIG block is replaced with a spare unit from a different Agilent instrument. After re-alignment of the YIG the unit functions correctly. The principle operation of the YIG oscillator is explained and the internals of the defective unit are examined under the microscope.

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