TSP #219 – Teardown & Repair of an Agilent 81101A 50MHz 20Vpp Pulse Generator

In this episode Shahriar takes a close look at an Agilent pulse generator which does not produce any output signal. The generator has an output ON/OFF function which can disconnect the unit using a microwave relay. The output spectrum of the faulty unit shows the presence of the desired spectrum and residue of the square wave signal.
The teardown shows that the output relay is not being engaged with the output is enabled. The fault is traced to the relay switch transistor (NPN) which does not respond to the control signal. The replacement NPN corrects the problem and the unit produces the correct output. The unit’s maximum output swing as well as frequency accuracy are verified using a R&S MXO-4 Series & a Rubidium frequency counter.

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TNP #25 – Teardown & Repair of a Keysight E36313A Triple Output Programmable DC Power Supply

In this episode Shahriar repairs a broken Keysight E36313A with a blown fuse and burnt smell coming from the unit. The teardown shows the dual-board design of the unit as well as the large toroidal transformer. The magic smoke has escaped from a dual Schottky diode power device with a Vf = 0.45V at If = 5A. The replacement eBay component is first verified to meet the specifications and installed in the power supply. The Keysight unit is then tested at a few output voltages and current to ensure proper functionality.

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TSP #218 – JouleScope JS220 Precision Energy Analyzer Scope Review, Teardown & Experiments

In this episode Shahriar takes a close look at the new JouleScope JS220 dynamic energy analyzer:

http://joulescope.com

The USB-C instrument architecture and details teardown is presented alongside the main PCB X-Ray images. The instrument’s unique six orders of magnitude current measurement and switching networks is also described and analyzed. The measurements confirm the six unique shunt resistors (alongside pairing CMOS devices) which can be chosen both manually and automatically by the autorunning software.
The GUI multimeter view is used to verify the accuracy of the unit across all current ranges and voltage ranges using a pair of Keithley 2450 SMUs. The dynamic behavior of the instrument is presented using a wide dynamic range load using various excitation waveforms and frequencies. Finally, a Z-Wave IoT motion sensor characteristics and communication patters is analyzed.

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TSP #217 – Teardown, Repair & Analysis of an Agilent E8267C 20GHz PSG RF Vector Signal Generator

In this episode Shahriar attempts the repair of an Agilent PSG Vector Signal Generator. Aside from excellent RF performance, the PSG series generators are also equipped with built-in baseband generators allowing for a wide range complex RF modulations. The instrument has been loaned to The Signal Path by AllTest:

https://alltest.net/

This particular unit fails the internal I/Q Calibration routines. This routine calibrates for image rejection, LO rejection as well as a wide range of I/Q routing, offsets, gain/phase corrections. The calibration errors points of the I/Q MUX board and the summing nodes inside that assembly. The measurements confirms that the Q signal exhibits large distortion.

The teardown reveals the complexity of the I/Q MUX board which comprises numerous op-amps, selectors, amplifiers & multiplexers. The block diagram of the I/Q mux is presented in details along with various measurements. The fault on the I/Q MUX board is traced to one multiplexer on the Q path. The IC is replaced and the waveforms return to their linear forms. The instrument passes the internal I/Q Calibration routine after the repair. The RF output of the unit is also verified and presented showing the correct operation of the vector modulation path.

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TNP #24 – Teardown & Experiments with the Melles-Griot Triple-Channel Piezoelectric Controller

In this episode Shahriar presents a three channel Melles-Griot piezoelectric controller which can be used in conjunction with piezoelectric actuator for exceptionally precise movements. The instrument is capable of producing three independent voltages up to 75V per channel. In addition, the unit can use external SUM/DIFF analog signals and adjust the output voltages accordingly.
The instrument is used with a Thor Labs XYZ stage to achieve sub-micron movement accuracy and control. The reverse effects also shown where a mechanical shock to to the XYZ stage produces pulses of voltage.

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