Tag Archive for Analog

Overview of the Tektronix MSO58 8-Channel 6.25GS/s 2GHz Mixed-Signal Oscilloscope

In this short episode Shahriar demonstrates an overview of the new Tektronix MSO58 8-Channel 6.25GS/s 2GHz Mixed-Signal Oscilloscope with up to 64-Bits of digital channels. The scope features independent ADC, data acquisition and memory per channel as well as FlexChannel architecture which allows each channel to act as either a 2GHz analog channel or an 8-Bit digital channel. The scope also features a brand new GUI interface on an HD 15.6″ display with significant performance enhancement and touch interface optimizations. A full review of the instrument will be provided in the future.

Teardown & Repair of a BK Precision 879B Handheld LCR Meter

In this short episode Shahriar repairs a more affordable instrument! This BK Precision LCR meter does not power up despite looking almost new. The teardown of the unit reveals several damaged components. Without any schematic and obscure part numbers some circuit configurations have to be reverse engineered. One of the main failed components is a TI DC-DC converter IC whose datahseet is examined during the repair.

The damaged components are replaced and the unit powers on normally. The performance of the instrument is verified using a HP LCR meter. The demonstrated Soldering Iron Stand can be found here.

DeoxIT Challenge & Restoration of a Precision Decade Resistor Box

In this short episode Shahriar attempts to revive a high-accuracy decade resistance box using the famous DeoxIT cleaning and restoration products from CAIG Laboratories. The DeoxIT D-Series products are particularly aimed at metal-metal contacts which have suffered oxidization and can provide a low-resistance repeatable contact after application.

The existing decade resistance box shows inconsistent measurements and intermittent contacts prior to the DeoxIT application. After spraying all contacts the instrument is significantly improved with repeatable and accurate resistance measurements. DeoxIT can be purchased from a variety of suppliers and vendors including Amazon.

Teardown, Repair and Experiments with a Tektronix RSA 6114A Real-Time Spectrum Analyzer

In this episode Shahriar attempts a difficult repair of a Tektronix RSA real-time spectrum analyzer. This well-equipped instrument reports several error messages during startup POST including LO Unlock as well as Signal Path failures. The service manual of the instrument does not provide any detailed block diagram and no schematics. Most failures require the instrument to be serviced by the Tektronix factory. The equipment has various advanced options including 110MHz analysis bandwidth, digital modulation analysis, wide-band IF output and deep memory.

The teardown of the instrument reveals a multi-board, multi-module design. The top of the instrument contains all digital blocks and boards while the bottom of the instrument houses the RF deck assembly. The RF deck is broken into various stages such as attenuator, RF switches, first converter, second converter, IF block, reference synthesizer and LO generator. For the purposes of addressing the YIG problems the LO board is examined. The problem is traced to two components, both dividers in the complex PLL system of the LO subsystem. The LO board is fully analyzed and described and the defective components re replaced.

The repaired instrument is tested for various functionality including DPX, de-modulation and measurement of beyond 8GHz CW tones. The instrument passes all self-tests, alignments and detailed diagnostics.

Teardown, Experiments & Calibration of an Ist-Rees Laser Spectrum Analyzer

In this short episode Shahriar takes a close look at an Ist-Rees laser spectrum analyzer. This simple instrument is based on a continuously rotating diffraction mirror to detect various wavelengths. A trigger signal is used to denote the beginning of the scan and the front-panel display shows the current selected wavelength. By aligning the output signal with the trigger signal the wavelength of the input light can be measured.

After the unit teardown, the instrument is used to measure the wavelength of a semiconductor 1310nm laser. The unit is calibrated using this source and is then used to measure the infrared leakage wavelength from a green laser pointer.

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