A1278 2011 13” MacBook Pro

{|class="wikitable" ! style="text-align:left;"| Problem ! Solution video source video source video source video source video source video source
 * Liquid Damage - No power on ||
 * Liquid Damage - No power on ||
 * Check for corrosion on the chip under the fan. Replace any chips in the area that appear corroded.
 * Constant power cycling||
 * Constant power cycling||
 * Take board outside of computer.
 * If issue is resolved, plug individual parts back in until issue appears again.
 * If issue appears when trackpad is plugged in, check booster sensor (U5805). PP5V_S3 may be blocked to pin two on this chip.
 * If pin 2 is corroded, replace U5805 to resolve this issue.
 * Doesn't turn on - No fan spin - Green light at the charger||
 * Doesn't turn on - No fan spin - Green light at the charger||
 * Go through all the powerrails listed in schematics - check which is missing => PP5V_S3 at 0
 * measure short to ground => no short to ground
 * put 5V(2 A max) at PP5V_S3 to see if it turns on => it turns on and draws 4.99V and 0.18A(increasing)
 * check in schematics
 * visual inspection: probe point P5VS3_vbst_r is red => indicator for water damage
 * measuring r7260 in restiance mode => OL
 * measuring r7260 on donor board => 0 Ohms
 * replacing the => fan spin
 * Doesn't turn on - No fan spin - Green light at the charger||
 * Doesn't turn on - No fan spin - Green light at the charger||
 * PPBUS_G3H was at 1.7V, needed to be 12.6V. CPU getting hot.
 * Issues in the VCore voltage generation circuit, where one transistor would stay open and allow too much voltage to the CPU.
 * One of Q7510, Q7520 or Q7550 and likely U7400 were defective so they all got replaced and this fixed the issue.
 * This video is a narration of the troubleshooting steps and resolution. No soldering shown.
 * Runs slow||
 * Runs slow||
 * SMC PBUS VSENSP reading below operating limit
 * Check R5304
 * Should read 2.0V~
 * If not R5304 then check C5304
 * Doesn't turn on - No Light On Charger - No Fan Spin||
 * Doesn't turn on - No Light On Charger - No Fan Spin||
 * Measure Voltages:
 * PP3V42=Good
 * PPBUSG3HOT=0.2V
 * SMC_BC_AOK=0V
 * U7000 ACIN (Pin 3)=0V
 * Measure Components:
 * R7010=Good
 * R7011=Good
 * Replace U7000 = Fan Spin!

If CHRG_ACIN has 4V:
 * Check Current Sensing Circuit (R7020, R7021, R7022), if good
 * Check for Short to Ground (plug in battery and test F7040 see Example: https://youtu.be/wPxYPrnoMZ4?t=721), if no Short
 * Check top of Q7030, if 0V
 * Check Q7080, if 0V
 * Check Q7085, if good, then ISL6259 needs to be replaced see example: https://www.youtube.com/watch?v=wPxYPrnoMZ4

video source Example: https://www.youtube.com/watch?v=ZxsMCf6P15A (short to ground on data line, measured at the pull-up resistors, caused by bad ISL6259)
 * Green light, doesn't turn on - 200mA||
 * Green light, doesn't turn on - 200mA||
 * Measured Voltages:
 * PP5V_S3 = 0V
 * P5VS3_EN_L was 3.5V to ENTRIP1 on TPS51125 (U7200)
 * When Q7221 was removed, P5VS3_EN_L was no longer telling U7200 to stop making PP5V_S3, and PP5V_S3 was good (5V).
 * The thermal camera was used to determine the the PCH (U1800) was running hot (50C)
 * P5VS3_EN_L was high because of Q7911 and PM_SLP_S4_L.
 * It was deemed that replacing the PCH was not economically viable, and the board did not get fixed in this video.
 * Battery not recognized
 * Can be caused by short to ground on data line between SMC and ISL6259 (chip for battery charging)
 * Can be caused by short to ground on data line between SMC and ISL6259 (chip for battery charging)
 * Not charging
 * Current sense circuit issues. R7052 was not 0 ohms U7000. Example https://www.youtube.com/watch?v=FGYrykiL9rA
 * Current sense circuit issues. R7052 was not 0 ohms U7000. Example https://www.youtube.com/watch?v=FGYrykiL9rA