How To Diagnose Fix An Iphone 7 That Does Not Charge 0006A Via Usb

How To Diagnose & Fix an iPhone 7 That Does Not Charge (0.006A via USB)

Source: https://repair.wiki/w/How_To_Diagnose_%26_Fix_an_iPhone_7_That_Does_Not_Charge%2C_Takes_0.006A_via_USB
Category: Repairs
Type: External SOP

Summary

iPhone 7 / 7 Plus turns on but does not charge. USB meter reads ~0.006A. Root cause is typically a faulty Tristar IC (U4001, part# 610A3B) on the main logic board. Requires BGA rework tools.

Equipment needed: Soldering iron, hot air station, microscope, multimeter, DC power supply or DT880, USB power meter. Optional: Tristar tester tool, thermal camera or freeze spray.

Procedure

Phase 1 — Rule Out Parts Issues

  1. Test the board with known-good screen, battery, and charging port flex (previously verified, not just new stock).
  2. Remove the board from housing; connect only screen, battery, and charging port, then plug in to charge and monitor USB meter.
  3. If current is still ~0.006A and no charging symbol appears, the fault is on the board — proceed to Phase 2.

Phase 2 — Confirm Tristar Fault

  1. (Optional) Run a Tristar tester (Smartmod Pro, ICC Pro, or JC Programmer). A “Tristar Fail” result strongly indicates a bad Tristar. Note: a “Tristar Pass” result does not rule out a bad Tristar.

  2. DC power supply boot current check:
    – If current draw is present before prompting boot → fault is a board short, not Tristar. Stop and investigate shorts.
    – If no current draw before boot prompt, and the first boot-sequence reading is ~0.150–0.250A → confirms Tristar fault.

  3. (Optional) Thermal check: Use a thermal camera or freeze spray on U4001 during boot prompt. Tristar running hot indicates failure, though it may not always heat up.

  4. Battery connector voltage check:
    – Connect only the charging port flex to the bare logic board (no screen, no battery).
    – Plug in a charging cable.
    – Set multimeter to DC volts; probe the two large pins on battery connector J2201.
    – < ~2V (typically 0.3–0.6V) → Tristar is bad.
    – ~3.7V → charging circuit is functional.

Phase 3 — Replace Tristar (U4001)

  1. Confirm the correct Tristar version: 610A3B (iPhone 7 and 7 Plus specific — earlier models use different versions).
  2. Tristar is partially covered by a shield. Do not cut or remove the shield. Remove the chip at an angle and install the replacement at an angle.
    – Cutting the shield risks damaging surrounding components and creates sharp edges that will pierce the charging port flex during reassembly, causing the fault to recur.

Phase 4 — Verify Repair

  1. Re-test with known-good screen, battery, and charging port. Charging current should be ≥1A.
  2. Re-run Tristar tester if available — should now pass.
  3. Check first boot-sequence current draw; should now be ~0.045A.
  4. Re-check battery connector voltage; should now read ~3.7V.
  5. Compare all readings to pre-repair results to confirm the fault is resolved.

Phase 5 — If Still Not Charging After Tristar Replacement

  1. Check for shorts around Tristar: probe both sides of each adjacent capacitor for continuity to ground.
  2. Inspect C4005 (TRISTAR_BYPASS capacitor) for short to ground — replace if shorted.
    • C4005 spec: 1.0µF, 6.3V, 0201 package
  3. Remove Tristar and diode-mode all Tristar pads; compare readings to boardview software (e.g., ZXW) and/or a known-good board.
  4. For any shorts found, use voltage injection to locate the shorted component.

Notes

  • USB charging current readings vary by cable and brick — check the brick’s output spec label and compare against a known-good iPhone 7 on the same cable/brick.
  • A battery near full charge or a degraded battery will show lower charging current; this is normal and not indicative of a fault.
  • Diode-mode readings should always be compared against a verified known-good board or boardview reference, not assumed values.