Hello everyone, I have two Sony WM‑EX910 units and one WM‑EX677 showing exactly the same defect: they do not start up when at room temperature. If I slightly warm up the board (leaving it in the sun for a few minutes, or even just holding it in my hand or bringing the soldering iron close), the unit powers on normally and then works for hours or even days, as long as the battery remains installed. If the battery is removed and the unit is left unused for a few hours/days, the problem reappears and it only works again after initial heating. When the unit is running, all voltages and audio/solenoid signals are correct. All IC solder joints in the power supply section have been reflowed and the traces checked. The EX910 does not use any electrolytic capacitors, but I measured the ESR of the tantalum capacitors and they all seem fine. I would like to know if anyone has faced this problem with these models and if there is any recommended modification or replacement to overcome the “cold start” defect. Thanks for your help!
