Sony Nwz-s639f Battery Replacement -

Over time, the internal resistance of the Li-Po cell increases. The electrolyte degrades. The result is not just shorter playtime but also potential swelling. A swollen battery can push against the LCD screen, causing white pressure spots or permanently damaging the display. If your NWZ-S639F’s screen has a dark cloud or the back casing feels bulging, stop using it immediately and replace the battery.

: If your Walkman still won't turn on after replacement, try pressing the RESET button with a small pin to kickstart the system. NWZ-S636F / S638F / S639F / S736F / S738F / S739F - Sony sony nwz-s639f battery replacement

| Problem | Likely Fix | | :--- | :--- | | Won't turn on after soldering | Double-check polarity (+/-). Resolder if reversed. | | Battery drains fast | You may have received a low-quality LIS943 clone. Re-replace with a better source. | | No sound on one side | You likely pinched a headphone jack wire during reassembly. Reopen and check. | Over time, the internal resistance of the Li-Po

To safely separate the case without scratching the aluminum. Tweezers: For handling small ribbon cables and tape. A swollen battery can push against the LCD

Required for most S-series models, as the battery leads are often soldered directly to the motherboard. NWZ-S639F Specifications - Sony UK