My AIWA HS-J303 MKII produces a light “popping” sound, like an electrical discharge, during playback. Previously, it had a howling noise issue. To address that, I cleaned the mainboard using an ultrasonic cleaner with PCB cleaning solution and replaced all the electrolytic capacitors. Three capacitor pads had lifted, so I referred to the circuit diagram and fixed them with jumper wires. Now the unit produces sound normally, the audio quality is good, and all functions are working as expected. However, a new issue has emerged: one audio channel emits a faint popping or discharging sound roughly every 4 seconds, with very precise intervals. I saw someone mention that it might be due to poor contact with the ground spring, so I cleaned that area thoroughly, but the issue persists. I’ve checked and rechecked multiple times, but the noise remains. Strangely, the popping interval sometimes speeds up, sometimes disappears entirely, and sometimes returns. When I disconnect one of the motor’s power wires and press play, the noise doesn’t occur. Whether or not a tape is inserted, the noise appears as long as the motor runs. It also happens during fast forward and rewind, but not when listening to the radio alone. This strongly suggests the motor is the source of interference. I’ve never disassembled the motor itself. What’s even stranger is that on one occasion, when I left the side cover off, the noise was gone — but as soon as I reattached the cover, the noise returned. At this point, I’m really at a loss and not sure what to check next. I’d really appreciate any insights or suggestions, especially if anyone has encountered a similar issue. Thank you!
