FAQ
TL;DR: 99.9% likelihood points to the charge IC near the coil — “99.9% that the chip next to the coil also went.” Diagnose shorts, inspect the coil, and replace the 358S 2166 if needed. [Elektroda, marnowak, post #17097143]
Why it matters: This FAQ helps DIYers and repair techs quickly pinpoint and fix Lenovo Yoga YT3-X50F charging failures after port or board swaps.
Quick Facts
- Symptom: LEDs indicate charging but battery level stays flat; voltage at test points 1–2 doesn’t rise. [Elektroda, hcn, post #17083971]
- A short between connector pins 2–3 can cause smoke and rapid heating; disconnect immediately. [Elektroda, pdemski, post #17084039]
- The charge IC next to the inductor commonly fails after a short (reported at 99.9% likelihood). [Elektroda, marnowak, post #17097143]
- Charger IC ID: 358S 2166 (aka 3585-2166); users report swaps from Samsung Tab T210/T211. [Elektroda, ArturoZacarias38, post #18889234]
- Typical part cost: ≈PLN 50 for the IC, plus labor for microsoldering. [Elektroda, gradek83, post #17085000]
How do I diagnose a YT3‑X50F that shows charging but the battery doesn’t fill?
Measure battery rail at marked test points (e.g., 1–2). If voltage doesn’t rise with the charger connected, the charging path is open. Inspect the USB sub‑board, the inductor near the port, and the adjacent charge IC. LEDs can light even when charging is inactive. [Elektroda, hcn, post #17083971]
I connected a new USB board and saw smoke—what likely shorted?
A manufacturing defect or solder bridge can short connector pins 2–3. That short draws high current, causing smoke and fast heating. Remove power, disconnect the sub‑board, and inspect under magnification before further tests. [Elektroda, pdemski, post #17084039]
What is the 3585‑2166 (358S 2166) charger IC, and what can replace it?
It’s the tablet’s charging controller near the inductor. A reported substitute is the 358S from Samsung Tab T210/T211. Users also note the lack of a Lenovo schematic, so cross‑checking footprints is essential during repair. [Elektroda, ArturoZacarias38, post #18889234]
Do I need to rework the inductor near the charge IC?
Yes, if it’s heat‑damaged or lifted. “You have to re‑solder the damaged coil,” and then verify for additional faults. Replace it if readings are abnormal or the core is cracked. [Elektroda, nutergsm, post #17084618]
After a short, what else commonly fails in this tablet?
The IC next to the coil is the typical casualty. One expert reports a 99.9% likelihood that this chip also fails. Inspect and plan to replace both the coil and the charge IC. [Elektroda, marnowak, post #17097143]
How much should I expect to pay for the charger IC replacement?
Approximate part cost is PLN 50 for the IC, plus labor for board‑level work. Final price increases if other parts are burned or pads need reconstruction. [Elektroda, gradek83, post #17085000]
Can I bypass the charger IC to get it working?
The thread’s practical path is sourcing and replacing the correct 358S 2166 IC. No safe or documented bypass is provided. Technicians perform like‑for‑like replacement instead of bypassing charging control. [Elektroda, ArturoZacarias38, post #18889234]
How do I check if the connector had a pins 2–3 short?
- Inspect the connector under magnification for a solder bridge between pins 2 and 3.
- Use a multimeter in continuity mode across pins 2–3 to confirm a short.
- Replace the faulty plug or sub‑board before applying power again. [Elektroda, pdemski, post #17084039]
What tools do I need for board‑level repair on the YT3‑X50F?
Use a hot‑air rework station, quality flux, leaded solder, ESD‑safe tweezers, microscope, and a reliable multimeter. These enable safe removal and replacement of the inductor and charge IC with clean joints. [iFixit, 2023]
Where can I find someone to do the repair for me?
Create a request in the forum’s Bazaar section to outsource the job. Service offers and paid repair inquiries belong there per forum guidance. [Elektroda, nutergsm, post #17084313]
Is there a schematic for the YT3‑X50F charging section?
A contributor could not find an official schematic for this Lenovo. Identification relies on visible markings and known cross‑references during diagnostics and repair. [Elektroda, ArturoZacarias38, post #18889234]
What does a burned inductor look like on this board?
Look for a ferrite‑core coil with chipped varnish or debris resembling crushed winding enamel. That appearance indicates overheating and likely failure. Replace or re‑solder and retest. [Elektroda, gradek83, post #17085000]
I see a small “diode” near the port is burnt—what is it likely?
Near USB/charge inputs, designers add TVS/ESD protection diodes to shunt surges. A visibly burnt package suggests the protector sacrificed itself and needs replacement. [Littelfuse, 2020]
Does swapping the USB sub‑board always fix charging on the YT3‑X50F?
No. In the discussed case, a new board lit the LEDs, but charging did not start. Upstream power‑management components were damaged and required board‑level repair. [Elektroda, hcn, post #17083971]
