Apple MacBook Air A1466 Notebook switch auto power off repair

Machine model: apple MacBook Air A1466

Motherboard model: 820-00165

Fault symptom: notebook switch auto power off

Maintenance process:

Macbook A1466 notebook, when the fault phenomenon is turned on,auto power off, and the current is about 0.2 or so. When the motherboard is removed, it is found to be Previously repaired, and there are traces of Flux and repairs on the motherboard in many places.

Apple MacBook Air A1466 Notebook switch auto power off repair Figure 1.

Apple MacBook Air A1466 Notebook switch auto power off repair Figure 2.

Apple MacBook Air A1466 Notebook switch auto power off repair Figure 3.
auto power off when the bare board is powered on, excluding the possibility of auto power off caused by peripherals. The maintenance directions are as follows:

BIOS failure, 2. The motherboard has Short circuit,3. The timing problem, 4. The VCC,5. The temperature control signal is missing, 6. It can’t afford the load, etc. The BIOS chip has been repaired at home. Measuring several VCC oscilloscopes, CPU 1.7V, memory 1.3V, bridge 1.05V, PP1V8_S3, PP5V_S4, etc., all maintained for about 500 milliseconds at the moment of power-on, and then dropped at the same time.

Apple MacBook Air A1466 Notebook switch auto power off repair Figure 4.

Apple MacBook Air A1466 Notebook switch auto power off repair Figure 5.
After auto power off, when the current returns to standby 0.02,switch can be started again. The standby PP3V3_S5 is also very stable and has not been turned off, indicating that there is no problem with VCC after standby and secondary conversion.

Next, let’s see whether the main VCC problem caused auto power off or PG caused it to drop after VCC was normal. If U1950 is removed, the bridge will not receive PCH_PWROK, and the secondary signal will not come out, which will not affect the previous signal. Let’s see if there is any problem in the period from VCC to PG. After being removed, the current is set at 0.18, and there is 3.3V at bit 1, bit 2 and bit 8 of pin of U1950, which proves that it is normal from standby to VCC to PG.These places didn’t cause auto power off.

Apple MacBook Air A1466 Notebook switch auto power off repair Figure 6.

Apple MacBook Air A1466 Notebook switch auto power off repair Figure 7.
Install U1950, test whether plaorm reset PLT_RESET_L sends out and test whether diode value reset to each chip after U2071 conversion is Short circuit. There is no action when the oscilloscope plaorm is reset, and U2071 chip 4 pin does not have Short circuit, that is, PLTRST is not sent to the bridge.

Apple MacBook Air A1466 Notebook switch auto power off repair Figure 8.
According to the time sequence, the bridge will send out PLTRST after receiving APWROK, but up to now, U1950R 5 pin and 3 pin have measured 3.3V of about 500MS, while the bridge does not send out PLTRST. There are two cases where the bridge is broken or the condition is not enough.

After auto power off, press Switch to get switch again. It can also be considered that the standby condition of the bridge is normal. All that is left is whether all kinds of VCC required by each module of the bridge are normal. The lack of VCC may lead to auto power off or not running code. After checking, an VCC found in CLK module has no action.

Apple MacBook Air A1466 Notebook switch auto power off repair Figure 9.
It is found that this VCC is renamed from PP1V05_S0 by a 0-ohm resistor R1270. The appearance of this resistor has been damaged, and the measuring front end of 1.05V has come out. Replace the resistor, and Connect the power supply can run normally when it is turned on.auto power off is no longer used.

Apple MacBook Air A1466 Notebook switch auto power off repair Figure 10.

Apple MacBook Air A1466 Notebook switch auto power off repair Figure 11.

Apple MacBook Air A1466 Notebook switch auto power off repair Figure 12.
When I connected the screen, I found that SN was unavailable.

Apple MacBook Air A1466 Notebook switch auto power off repair Figure 13.
Read out the BIOS, add SN, brush it back, and then turn it on to display SSN normally.

Apple MacBook Air A1466 Notebook switch auto power off repair Figure 14.

Apple MacBook Air A1466 Notebook switch auto power off repair Figure 15.

Apple MacBook Air A1466 Notebook switch auto power off repair Figure 16.
This fault is that auto power off is powered on due to the lack of VCC in the bridge module, which causes the plaorm to reset. After replacing the resistor, it is normal, so the maintenance is over.

Post Views: 317