Dilshan R Jayakody’s Web Log

A few months ago, our AMD Ryzen™ 5 computer started giving some startup issues. At first, this problem happened randomly, and then it started happening at every bootup. The symptom is that if the computer shuts down after a boot, it will not start on the next power cycle(s). If we turn it off for 30 or 45 minutes and then turn it on, it will start working without any problems. This problem did not occur on warm restarts. After changing power supply units, we realized that the problem was with the PSU. This suspicious unit is a Corsair VS550 PSU . Corsair VS550 PSU PCB. Based on the symptoms, we thought the problem was with a capacitor on the PSU board. We disassembled the PSU and checked all the electrolytic capacitors, but we could not find any faulty capacitor(s). To further investigate this issue, we connected the PS-ON terminal to the ground ( GND ) and started the PSU. During this test, we see that the PSU is performing well on this condition. As we examine further, we find t

In this project, we extend the shortwave superheterodyne receiver we developed a few years ago . Like the previous design, this receiver operates on the traditional superheterodyne principle.  In this upgrade, we enhanced the local oscillator with Si5351 clock generator module and Arduino control circuit. Compared to the old design, this new receiver uses an improved version of an intermediate frequency amplifier with 3 I.F transformers. In this new design, we divide this receiver into several blocks, which include, mixer with a detector, a local oscillator, and an I.F amplifier. The I.F amplifier builds into one PCB. The filter stage, mixer, and detector stages place in another PCB. Prototype version of 455kHz I.F amplifier. In this prototype build, the Si5351 clock generator drives using an Arduino Uno board. With the given sketch, the user can tune and switch the shortwave meter bands using a rotary encoder. The supplied sketch support clock generation from 5205kHz (tuner frequ