In this episode Shahriar attempts the repair of a Matsusada RE-600-1.6V 1.6A power supply. This low profile power supply is intended for rack-mount application and has been likely used in a vapor deposition system before it has failed. The scent from the unit hints at capacitor failures due to thermal stress over a long period of time. The teardown of the unit reveals the low-profile construction as well as the ventilation air flow. The faulty capacitors are replaced with higher temperature rated units. Unfortunately further faults are detected and it is revealed that the main switching transistors have also failed. All part number of all ICs and control modules are either sanded off, or permanently potted. Since no schematic is available, the repair has to be temporarily put on hold.

The Signal Path
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In this episode, Shahriar repairs a few PXI module cards including a PXI-2596 Microwave Switch, a PXI-4461 Signal Analyzer and a PXI-4071 7.5 Digit FlexDMM unit. The PXI-2596 and PXI-4461 have both suffered mechanical damage to the on-board components. Some re-wiring as well as component replacement is necessary to correct the problems.

The PXI-4071 module halts the PXI system boot up entirely. The card is missing a flash memory IC and could potentially have a bad PXI bus main IC. The PXI bus IC replacement does not correct the problem. This implies a missing firmware on the flash memory IC.

The Signal Path
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In this episode Shahriar takes a close look at one of Keysight (Agilent) InfiniMax III active probes. The model N2802A offers 25GHz of analog bandwidth, 17.5pS of rise time and a total differential input capacitance of 32fF at 10k-Ohm input impedance. The front-end amplifier of this active probe is designed in an in-house InP process, the same process responsible for the front-end of the X-Series Keysight oscilloscopes.

The teardown of the probe shows the control circuitry in the main probe body built around a PIC 16F877 microcontroller coupled to a DAC, EEPROM memory and various high-current and precision op-amps for biasing. The main front-end microwave module reveals the InP ASIC and supporting microwave circuity. There seems to be a dual-path design to provide a large DC common-mode offset capability as well as a high-bandwidth.

The Signal Path Blog
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In this episode Shahriar and Timo demonstrate the design methodology of an FPGA based 32×32 RGB LED matrix driver. Timo has kindly devoted some of his time to describe the block diagram and the thought process which goes into designing this type of FPGA display driver. The various components of the overall system (PLL, UART, and Display Controller) are shown along with the simulation data. The outputs of the Spartan-6 FPGA board are then measured using a Keysight S-Series oscilloscope. The design of the RGB matrix is also demonstrated using a custom clock interface sent wirelessly to the unit via Bluetooth.

The Signal Path Blog
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In this episode Shahriar builds a magical charger circuit that has an efficiency of tens-of-thousands of percent! But not to worry, it is a trick and the trick is revealed in the video. The purpose of the video is to discuss the nature of the scientific method and our society’s need for free education.