In this episode Shahriar investigates a faulty Agilent E3631A 80W triple output power supply. The instrument powers on, display a fully illuminated VFD display before a long beep and dark screen. The disassembled unit reveals a two board construction. After an unfortunate finger burning experience, the fault is traced to pair of extremely hot voltage regulators and Zener diodes. The temperature of these components is measured using a thermal camera and reach 400C! The schematic of the power supply is examined and the appropriate components are replaced. The performance of the unit is verified after the repair.
The Signal Path Blog