In this episode Shahriar investigates a peculiar problem with a SRS DS345 function generator. The instrument does not appear to produce the correct output signal frequency. After some investigation it becomes clear that a few of the display digits are not active which hide the actual frequency settings. The problem is traced to a broken resistor on the display driver. The schematic of the instrument shows that the resistor is responsible for strobing the affected seven-segment digit. After the repair, the instrument’s performance is verified including the OCXO accuracy.
Tag Archive for Analog
In this episode Shahriar investigates a faulty Agilent 53152A 46GHz frequency counter. The instrument does not power on and shows no sign of internal voltage presence. Teardown of the instrument reveals a large PCB where all analog and digital circuity is contained. The power supply module is a module components and upon measurements shows no activity.
The power supply is a simple switching architecture with functioning input rectifier and capacitor filter. By using an oscilloscope it is clear that the power supply PWM controller attempts to start. However, the main power supply pin shows unstable voltages indicating inadequate charge retention on the rectifying capacitor. Replacing the capacitor revives the startup condition and the power supply function returns. The PWM controller and main switching transistors are also replaced with new ones. After this repair the unit powers on and passes all self-tests. The unit can successfully measure signal frequencies and power.
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.
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.
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.