In this episode Shahriar repairs a Keysight AXIe Chassis (M9505A) with a broken power button. The power button (with built-in LED) are replaced with a functionality-similar setup. The teardown and architecture of the System Controller and Embedded Controller Module are also presented.
The star of the video is an M8190A Dual-Channel 12GS/s 12-bit (or 8GS/s 14-bit) Arbitrary Waveform Generator module. The instrument provides in excess of 90dBc SFDR, 2G-Samples of memory per-channel, digital up-converter, built-in secondary amplifier path and up to 5GHz of analog output bandwidth. The module is coupled with a Keysight S-Series Oscilloscope for experiments showing multi-tone performance as well as image-rejection and extraordinary EVM performance with modulated signals.
In this episode Shahriar diagnoses a malfunctioning Agilent 86118A 70GHz Dual Remote Sampling Head. With 70GHz of analog bandwidth per channel, this module definitely deserves a repair.
Unfortunately most failed remote-head modules aren’t repairable if the damage is in the sensitive proprietary III/V front-end IC. However, in this situation the module intermittently fails calibration which is more promising. The teardown reveals the architecture of the module from the point of view of the analog and strobe paths. Measurements on the strobe path also show a potential failure on the power-amplifier/splitter network which feeds the two remote-heads. A pair of transistors are replaced on the strobe path which correct the problem. The unit passes calibration and is then used for various eye-diagram measurements to verify full functionality.
The network analyzer is missing the main HDD which initially prevents it from being tested. An image from a donor E5701C instrument is used to boot the unit and gain access to the instrument firmware. The unit shows an inaccurate S11 with an open Port 1 while S22 shows a perfect reflection. This indicates a potential problem with the Port 1 T/R module. Teardown of the module reveals catastrophic damage to the resistive front-end coupler which has been mostly likely caused by a large RF input power incident. After cleaning the PCB area, a replacement coupler is constructed. The repaired unit is checked for full self-test and used to measure a YIG tuneable filter.
You can may check the Andostar microscope lineup here. (Direct Link / Not-tracked)
More information about Wheatstone Bridge can be found here.
In this episode Shahriar repairs a Noise-XT 2MHz – 7GHz Ultra-Low Phase-Noise Clock Synthesizer. The instrument’s history indicates that it has suffered a fall from a work table. After a lot of difficulty, the instrument control software was found so that the unit can be tested.
Initial tests reveal that a very small output is present, however nearly 40dB below the desired value. The unit teardown shows an architecture based on dual Analog Devices DDS 14-bits DACs in conjunction with a Z-COMM VCO and a series of dividers & frequency multipliers. A detailed analysis of the unit is presented.
RF and analog measurements indicate that the RF connector is not making adequate contact with the final trace of the RF output. This explains the low output power. This problem is resolved by replacing the SMA connector entirely. The device output power, frequency accuracy, stability as well as cross-correlation phase-noise measurements are presented.
In this episode Shahriar reviews the top-of-the-line Tektronix 6-Series Oscilloscope. This 4-channel instrument offers 8-GHz of bandwidth at 25GS/s on all channel independently. Tektronix has made great strides in offering low-noise front-end custom ASICs combined with hardware digital down-conversion built into the core of the 6-Series. This enables advanced triggering across in both time and frequency domains as well as multi-domain correlated measurements.
This review is organized as follows:
00:06 – Introductions
01:42 – Instrument design, front and back panels
03:34 – Full acquisition board teardown, analysis and architecture
18:11 – PLL Experiment: Spectrum View, advanced triggering, PLL characterization and debugging
38:33 – Backplane Communication: Jitter analysis, eye diagrams, jitter composition, cross-talk
49:24 – Concluding remarks
The Signal Path (TSP) is an electrical engineering video blog for industry professionals, students and hobbyists. TSP is a non-for-profit website dedicated to provide free education spanning a wide range of electrical engineering topics. Equipment reviews, tutorials and repair videos are posted regularly.