In this episode Shahriar examines a faulty Fluke PM6303A Automatic RCL Meter. This unit power on however reports the incorrect measured value for all components. The instrument also does not provide the built-in 2V bias. After a quick teardown of the unit, physical damage to several input resistors can be observed. It becomes clear that a high-voltage discharge has caused a cascade failure of several components on the input signal path. These faults are traced to a chain of protection Zener diodes, resistors and general purpose diodes. After all the components have been replaced, the unit’s functionality is restored.
The schematic and block diagram of the unit is also presented and the principle of operation is explained. The repaired instrument is then used to measure several components to verify is functionality.
In this episode Shahriar repairs a Fluke PM6680B 225MHz High Resolution Frequency Counter. This unit which is equipped with a soft power button, does not power on. The standby LED is dimly lit and a high-frequency noise is emitted from the unit. This points to a switching power supply failure. The power supply is a simple fly-back converter with three outputs (5V, 18V, -8V). The 5V output is regulated while the other two outputs are single diode rectified.
The fault is traced to a bad precision reference IC which is replaced. The performance of the power supply is verified and the instrument powers on. An OCXO is used to calibrate the 10MHz reference crystal of the unit after the repair is completed.
In this episode Shahriar examines a faulty Valhalla 2701C Programmable Precision DC Reference instrument. Valhalla Scientific’s 2701C Programmable Precision DC Voltage Calibrator delivers ultra-precision, ultra-stable DC voltage from 100 nanovolts to 1200 volts. This unit does not have a working front-panel LCD screen. Luckily, that problem is resolved very quickly.
The internal build and operation of the unit is briefly examined and the instrument is calibrated using a Keithley DMM7510 7.5-digit multimeter. It is possible to upgrade this unit to a more stable and accurate reference voltage generator or to add the reference current capability to it.
In this episode Shahriar takes a close look at the FLIR MR160 Thermal Imaging and Moisture Meter. Featuring Infrared Guided Measurement (IGM) technology powered by a FLIR Lepton® thermal imaging sensor, MR160 helps you quickly see temperature patterns that point to potential hidden moisture so you know right where to place the meter probe to capture accurate readings.
After an overview of the camera functions a full teardown of the instrument is presented. The FLIR MR160 is based on a single PIC32 processor with built-in capacitance measurement capability. The MR160 is then used to detect a moisture spot on a floor tiling. The presence of moisture is then verified with both the pin-less and pin-based moisture measurement capability of the MR160. Finally, the MR160 is also used to measure temperature variation across a bank of resistors.
The full instrument block diagram is presented with focus on various signal paths and frequency planning. Several of internal modules (RF Front-End, Digital Baseband Processor and LO Synthesizer) are also presented and compared with the block diagram. In order to examine the instrument’s capabilities in a real-world situation, a complete superheterodyne wireless transceiver with a sliding-IF receiver is designed and examined. Each component in the system (LNA, mixer, PLL, etc.) is individually characterized by using the EXA Signal Analyzer. The complete system measurements are also presented.
Various chapters in the video can be found at the following time marks:
X-Series model comparison (0:50)
EXA block diagrams and principle of operation (4:27)
Various board teardown and examination (20:39)
Instrument front/back panel overview (37:05)
Wireless experiment setup description (43:22)
Doubler characterization with EXG as the tracking generator (45:31)
LNA and mixer gain and NF by using Noise Figure personality (57:31)
Signal-Hound VSG25A I/Q modulator characterization, OBW, ACPR, TOI (1:08:57)
PLL characterization with Phase Noise personality (1:19:49)
Full transmitter measurement with Keysight VSA (1:26:08)
Full wireless link characterization with Keysight VSA (1:30:28)
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.