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

How To Diagnose & Fix an iPhone 7 That Does Not Charge (Takes 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 ≈0.006–0.007A. Root cause is typically a failed Tristar IC (U4001, part# 610A3B) on the logic board.

Procedure

Diagnostic Steps

  1. Rule out parts issues — Test with known-good charging port flex and battery. Remove the board from housing and connect only screen, battery, and charging port. If USB meter still reads ≈0.006A with no charging symbol, the fault is on the board.

  2. Tristar Tester (optional) — Use a Smartmod Pro, ICC Pro, or JC Programmer Tristar Tester. A “Tristar Fail” result is a strong indicator of bad Tristar. Note: a “Tristar Pass” result does not rule out a bad Tristar.

  3. DC Power Supply boot current check — Connect the board to a DC power supply or DT880.
    – Current draw before prompting boot = not a Tristar issue (look for a board short instead).
    – No current draw before boot prompt, but first draw after boot prompt is ≈0.150–0.250A = bad Tristar confirmed.

  4. Check Tristar for heat (optional) — Use a thermal camera or freeze spray after prompting boot. A bad Tristar typically gets hot, though not always.

  5. Check voltage at battery connector J2201 — Connect only the charging port flex to the logic board (no screen, no battery). Plug in the charging cable. Set multimeter to DC volts and probe the two large battery pins on J2201.
    – Voltage ≤ ~0.300–0.600V → Tristar is bad.
    – Voltage ≈ 3.7V → charging circuit is functioning.

Repair Steps

  1. Replace Tristar U4001 — Use part# 610A3B (specific to iPhone 7/7 Plus; earlier models use a different version).
    – Tristar is partially covered by a shield. Remove and install the chip at an angle — do not remove or cut the shield. Cutting creates sharp edges that can pierce the charging port flex and cause re-failure.

Post-Replacement Verification

  1. Confirm USB charging current returns to ≈1A or more with known-good screen, battery, and port.
  2. Re-run Tristar Tester — should now pass.
  3. First boot current draw after replacement should be ≈0.045A.
  4. Confirm Tristar no longer overheats.
  5. Confirm battery connector voltage reads ≈3.7V (Step 5 method).

If Still Not Charging After Tristar Replacement

  1. Check for shorts on capacitors surrounding Tristar — probe each side of nearby capacitors for continuity to ground.
  2. Inspect C4005 (TRISTAR_BYPASS cap) for short to ground — replace if shorted. Value: 1.0 µF, 6.3V, 0201 package.
  3. Remove Tristar and diode-mode all Tristar pads. Compare readings against boardview software (e.g., ZXW) or a known-good board.
  4. If shorts are found, inject voltage to isolate the shorted capacitor.

Notes

  • Always use known-good (previously verified) parts during diagnosis — new stock can be defective.
  • Different charging bricks and cables produce slightly different USB current readings; calibrate expectations using a known-good iPhone on the same equipment.
  • A nearly full or degraded battery will charge at a lower current — factor this in when evaluating post-repair results.
  • Tristar Tester tools are a useful clue but are not 100% reliable in either direction.