Apple MacBook Air A1932
| Problem Description | Symptoms | Solution | Source |
|---|---|---|---|
| No power. | - May be pulling 5V or 20V but at very low amperage. - SLPS2R and AWAKE voltages/signals cycling | - Check resistance on PP5V_G3S should fairly high, well within the kilo-ohms. Voltage should be around 5v. Values less than 4.9v should be considered abnormal. - Check resistance on PP3v3_G3S should fairly high, well within the kilo-ohms. Voltage should be around 3.3v. Values less than 3.215v should be considered abnormal. - Check resistance on PP1v8_G3S should fairly high, well within the kilo-ohms. Voltage should be around 1.8v. Values less than 1.7v should be considered abnormal. - Check resistance on PP3V_G3H should fairly high, well within the kilo-ohms. Voltage should be around 3v. Values less than 2.915v should be considered abnormal. - If no shorts were found on the listed rails above, replace U7800. - If you found a short on the listed rails above, inject 1v into the rail and perform thermal imaging. Replace the shorted component. | Source |
| No power. | - Pulls 5V 0.10A/0.25A - Causes ampreader to power cycle. - Stuck in DFU mode. | - Revive or restore T2 firmware via Apple Configurator 2. - Ensure you’re running the latest macOS version for consistent results. - You should see a big square icon pop up that says “DFU” or rarely, “RECOVERY”. Click the icon, Navigate to the top menu bar click “Actions” then “Advanced”. Select Revive device. You will see a progress bar appear. This process can take anywhere from 2 minutes to over 30 minutes in some cases. It is important to note, if the device is in Recovery mode, the end user may have brought the device to another repair shop or Apple first, who attempted a DFU revive which failed. You may have a secondary issue if the revive fails again. - SELECTING RESTORE WILL WIPE ALL USER DATA! | Follow the provided Apple support article for the procedure. Source |
| No power. | - Pulls 5V 0.10A/0.25A - Causes ampreader to power cycle. - PP3v3_G3H_RTC Low or Absent - Not stuck in DFU mode. | PP3v3_G3H_RTC powers the “brain” functionality of the CD3215 USB-C controllers which allows negotiation with the USB-C charger to allow 20 V. When PP3v3_G3H_RTC is shorted, low, or absent, this communication cannot take place, and the device will be stuck at 5 V. On the 820-01521, U6960 generates PP3v3_G3H_RTC. U6960 is a buck converter which lowers the voltage from PPBUS_G3H (≈12 V) to 3.3 V. Since PPBUS_G3H is the VIN (voltage input), we must get PPBUS_G3H before we get PP3v3_G3H_RTC. - Diagnose possible shorted capacitor around CD3215 or from CD3215 itself. - Check GHGR_EN_MVR signal produced by ISL9240 (U7000). - If PP3v3_G3H_RTC is not shorted, check for its enable signal, GHGR_EN_MVR. CHGR_EN_MVR is produced by the ISL9240 (U7000). The ISL9240 commonly fails in a way that prevents CHGR_EN_MVR from being produced. If the enable signal above is missing, replace the ISL9240 (U7000.) - PP3v3_G3H_RTC can also be pulled low by PP3v3_UPC_XA_LDO or PP3v3_UPC_XB_LDO, so if you have no measurable short to ground, and your enable/VIN is present, check both the above rails for a short or low resistance to ground. Low resistance to ground/short on the above LDO lines will usually be caused by a bad CD3215. - Replace ISL9240 (U7000) if enable signal is missing. | Source |
| No power. | - Pulls 5V 0.10A/0.25A - Causes ampreader to power cycle. - Not stuck in DFU mode. | - If you are getting 5 V on PPDCIN_G3H, the ISL9240 is likely the cause of the problem, however we still need to check a few things before replacing the chip. The ISL9240 relies on a series of current sensing resistors to measure the amount of power being used by its output rail, PPBUS_G3H. If one of these resistors is blown, the chip will think that something on the output is pulling too much power, and it will disable itself as a protection measure. - Check current sensing resistors: R7021, R7022, R7061, R7062. - Their values are all 1Ohm - Replace ISL9240 if the resistors are normal. | |
| No power. | - PPDCIN_G3H missing with no short | - Usually, when a CD3215 is at fault, you will get 5 V on PPDCIN_G3H on one port, but not the other. The CD3215 that corresponds to the port where PPDCIN_G3H missing will usually be the cause of the fault. - To diagnose which CD3215 is not opening the DC IN MOSFET you will need to take 2 measurements, one to determine which CD3215 is in use and another to confirm which CD3215 is not opening the DC IN MOSFET. First, measure voltage on F3000 and F3010. One will measure 0 V, and one will measure 5 V. The fuse that measures 5 V corresponds with the CD3215 in use. - F3000 goes to U3100 and F3010 goes to U3200. Each fuse corresponds to a USB-C port. - Check PPDCIN_G3H voltage on both ports. The port that demonstrates missing PPDCIN_G3H voltage will correspond with the failed CD3215. - Be sure to use a CD3215C00 or CD3215C00Z. A CD3215B03 will not work. | |
| No power. | - Pulls 20V 0.03/0.06A - PP3v3_S5 shorted to ground | - If PP3v3_S5 is shorted to ground, pin 5 of U4885 is a good place to inject voltage to. - 1v at 5 amps is an appropriate voltage to inject into the line. - With voltage being injected, perform thermal imaging of the board. If thermal imaging is not available, feel around the board to see where it is getting warm. Once the area is localized, add a small amount of isopropyl alcohol to the area to localize the shorted component. - Once the shorted component is localized, replace the shorted component. - If PP1v8_S5 is shorted to ground, CC722/CC723 is a good place to inject voltage to. - 1v at 5 amps is an appropriate voltage to inject into the line. - With voltage being injected, perform thermal imaging of the board. If thermal imaging is not available, feel around the board to see where it is getting warm. Once the area is localized, add a small amount of isopropyl alcohol to the area to localize the shorted component. - Once the shorted component is localized, replace the shorted component. | Source |
| No power. | P5VG3S_EN is low or missing. | Check U7800 outputs: - PP1v8_SLPS2R - Normal voltage ~1.8v - PP1v1_SLPS2R - Normal voltage ~1.1v - PP0v9_SLPDDR - Normal voltage ~ 0.9v - PPVDDCPU_AWAKE ~ Normal voltage ~ 1.06v - PP0v82_SLPDDR ~ Normal voltage ~ 0.82v If any of the above rails is missing, U7800 may be bad, the rail may be shorted, or the T2 may not be communicating with U7800. Many of these rails will read 50-100 Ω to ground. | |
| No power. | Above solutions did not work. | - If no short is found on PP3v3_S5, and the device is not in DFU or recovery mode, you can try forcing a firmware revive. - Attempt to restore BridgeOs firmware via Apple Configurator 2 by placing the device into DFU mode. - STOP! Before you begin, is your Mac on the LATEST VERSION of MacOs? If not, update your system before proceeding. Forcing a MacBook into DFU mode, and attempting to restore BridgeOs firmware on a old version of MacOs may result in a bricked device. - Selecting restore will wipe all user data. - Follow the instructions on this Apple support article on how to revive or restore T2/BridgeOs firmware, including on how to force a Intel based MacBook into DFU mode by using a key combination. If the device fails the firmware revive or restore, the T2 chip or one of the NANDs is likely dead or is receiving unstable power from the PMIC (U7800) causing it to crash. If the device fails the firmware revive, you can try empirically replacing U7800. Replacing U7800 should be seen as a last ditch effort, as it only works in a small amount of cases, and does not have a definitive diagnostic test to determine if it is bad. | Source |
| High fan speed, hangs on boot logo. | - Attempt to run built in Apple diagnostics. - Check for liquid damage. - Replace the battery. - Replace the trackpad or trackpad cable. | Source | |
| No backlight. | - Check for short on backlight output PPVOUT_LCDBKLT_F - C8469 or adjacent capacitors in the series is an appropriate area to measure, since it does not require removal of the system board. - If a short to ground is measured, unplug the display connector to rule out a potential short to ground within the TCON board or LED strip of the display. - If it is shorted, Identify and replace the shorted component. (Check with and without the display connected, a short is commonly caused by a shorted capacitor. Could also inject 10v at 5 amps, thermally image the board, or use comparable short detection methods.) - Else, replace F8400 (Backlight Fuse) (0603 package size, 3 amp, 32v fuse. Brand does not matter.) | Source | |
| No backlight. | - Water damage present. | - Examine U8400 if corroded along with adjacent corroded components. - Ensure that the backlight circuit has its input voltage (VIN) by measuring on BOTH SIDES of F8400 (Figure 3), which is the backlight fuse. - Voltage on both sides of the fuse should be equivalent to PPBUS_G3H. - The backlight fuse can blow in response to a previous short to ground in the backlight circuit, or due to the screen being plugged in without the battery disconnected. - Rarely, the backlight fuse can become open (blown) due to development of sulfur deposits on the fuses’ filament , or due to micro manufacturing defects on the fuses filament. - If the backlight fuse is blown, check for a short on backlight output (PPVOUT_S0_LCDBKLT_F) and on backlight input (PPVIN_S0SW_LCDBKLT_F). If the fuse is blown, proceed to the “Backlight fuse (F8400) blown in the absence of a short to ground” repair steps below If voltage is normal on both sides of the backlight fuse, proceed to the next step. - Check that the backlight circuit is being enabled. The screen will need to be connected for the enable signal to be sent out. - With the board on your bench, with a known good screen connected, measure voltage on pins 1 and 2 of R8442. - You should have ~3.3v. Low voltage (less than 3.3v but more than 0v) on pin 2 of R8442 (Figure 4) is suggestive of an issue with U8400. - If you have 0v on pin 1 of R8442, the backlight circuit is not being told to turn on, which raises the possibility of a CPU issue, or an issue with the display cable/connector. - Check the 5v inputs to U8400 PP5v_S0_BKLT_D - PP5v_S0_LCDBKLT_D can be measured on R8444. - Be sure to check voltage on both sides of the resistor. If voltage is lower on one side of the resistor, R8444 or R8445 is likely blown, probably due to a short within U8400. - If PP5v_S0_LCDBKLT_D is low (Substantially lower than 5v), replace U8400 AND R8444 as R8444 acts as a current limiting resistor to protect PP5v_G3S, and likely blew as a result of an internal short within U8400. - If you have low voltage on pin 2 of R8442 with normal voltage on pin 1 of R8842, replace U8400. - If VIN, EN, and PP5v_S0_LCDBKLT_D are all present at normal levels, and you do not have backlight, replace U8400. - If EDP_BKLT_EN is missing, U8400 is NOT the cause of the issue. | Source |
| No camera detected. | - Possible burned or exploded L8570 filter on TCON board | - Verify camera function using a KNOWN GOOD display assembly. - If the camera works with a different display, the original display might be faulty. - Make sure to check L8570 before diagnosing the display issue. -Understand that L8570 failure indicates a catastrophic short within the TCON board of the display or a melted/corroded display cable/connector. - Repair L8570 only after addressing the display issue, as L8570 might fail again if the display issue persists. - When replacing L8570, address corresponding pad and trace damage. - Use 36 or 37 AWG enamel coated copper wire for jumper wires due to webcam and ambient light sensor power requirements. - The closest recommended jumper point for the input side of the filter (PP5v_G3S) is R7100/C7296 if the traces and vias for PP5v_G3S are not damaged in that area. - Apply conformal coating to jumper wire. - Use a 120 Ohm ferrite filter rated for 1.5 amps (402 package size). - After replacing L8570 and addressing trace issues, replace the display assembly or repair it by replacing damaged cables/connectors. | Source |
| No camera detected. | - L8570 Normal | - Attempt to restore T2/BridgeOs firmware via Apple Configurator 2 by entering DFU mode. - Ensure your Mac is on the latest macOS version. - Follow Apple’s support article on reviving or restoring T2/BridgeOs firmware. - If no camera function after firmware revive, and other causes are ruled out, U8595 might be faulty, or there could be trace/resistor issues between the camera connector/U8595 or between U8595 and the T2 chip. - A hardware issue with the T2 chip might also cause camera detection problems. | Source |