I’ve been doing laptop and Apple mobile maintenance for years. One year ago, I started Apple laptop maintenance. Through one-year exploration and research, I’ve got some experiences to share with you. Below are some common errors that I summarized. By common errors, I mean errors that I came across may times. There might be mistakes and omissions, welcome to correct them and comment below.

Here I omits some old models like A1278, A1286 and super new models like A2159 and A2144 that rarely repaired in daily. B+short circuit can be easily handled by thermal imaging.

A1369: Old model, rarely repair.

A1398: Mostly graphics card error, occurring in Southbridge brand. Mostly due to people connecting the cables of small motherboard in an opposite direction. In this situation, I usually use hot air gun before getting bga. If graphics card can’t be changed, then I usually update bios.

A1465: Mostly CPU error. Hard to repair. Once I get it worked after changing memory particles.

A1466: Mostly water sensor error. Warning: Sometime there’s no lighting, neither power even resistance value is normal. This test point is powered on by lighting control system which  will be possibly burnt out.


Sometimes water sensor is repaired, but still no lighting neither power. Then it’s possible that fuse is burnt out. You might get it worked after testing on/ff controller. Same situation occurs in A1465.


0.12A on electric source , possibly because electric capacity pp5v-s5 is not working


Abnormal Pp3.42v-g3h voltage is possibly due to resistors. In order to reduce maintenance, chips are to be changed together.

A1425: no dimming, constant current, power failure, battery not to be recognized, and fan spinning are mostly caused by by a failed EC. And EC is super expensive.

A1502: Haven’t repaired much of this model, but learned lessons. This model has some different generations. One of them is 4924 which has to connect battery to get power on. Other generations are powered on directly, but 4924 is not. Once upon a time it took me loads of time to get it right. It did not work even I connected it to battery. It’s chargeable and there’s voltage in battery. Unable to figure out why, I simply ordered a new battery, then it worked! Never ever thought it’s a failed battery!

A1534: Mostly CPU and hard disk error. Even get it repaired, won’t last long.

A1706: This model is the most popular. Seen it a lot.
cd3515c00: One failed chip among four, but booster is normal, no lighting. Here is a tip to identify the general performance of four power supply chips(cc1, cc2 communication) of all models with thunderbolt without removing motherboard. Remove the circuit board of thunderbolt, do ground resistance testing at both sides at the second and third points above and below, record the data on point map. When connect red pen to GND, it’s around 570. When black pen, it’s around 1350. BTW iPadPro 11inch and 12.9inch after 2018 are using cd3515c00 chip as well. Maintenance method is the same. There’s a converter chip between power supply chip and cc1 and cc2. Water seepage and over-charging are easily to burn converter chip. Further more, power supply chip u2 is also in charge of this, so maintenance is relatively more complicated. Power supply chip i2c is connected to CPU, so it’s likely that water seepage burns out chips and CPU at the same time.


9239hi chip is easily failed, same as A1707. Mostly no booster, no dimming, no pp3.3v-g3h shown etc.


The short circuit of EDP signal will cause no signal on screen. External power source is going to work for a while, but it’ll completely fail afterwards, which damages CPU. You can only deal with it by changing CPU.


Failed touchbar and t1 are the same as A1707, which fail to start system due to a key updating error. This is possibly due to t1 itself, and peripheral issues such as power supply chip, inlet chip etc. In this situation, I suggest test peripheral resistance value. Change power supply chip firstly. T1 requires fingerprint to log in. Once it’s changed, fingerprint will be out of validity. But a complete set will do. There’s few sets in the market, but you can look for a second-hand.


Btw, 4 power supply chips with pp3.3v-g3h all around can cause damage and short circuit easily.

A1707: In this model, EDP signal can cause short circuit easily, which cause no data shown on screen. But this model has a converter chip in the middle of CPU and graphics card. Changing it directly.


Further more, for this model, errors are mostly caused by water seepage. It’s because this model has no glue, while A1706 does. For Southbridge brand, error mostly caused by water seepage. You can change it directly. All models have sleep sensor chip. You can re-start smc to fix no dimming caused by water seepage.

A1708: This model mostly has burnt-out lighting issue caused by water seepage. Sometimes it’s severe burnt out to damage circuit board completely.
Try pp1v-s5 to connect to CPU. Water seepage causes burn out easily. Change CPU if there’s short circuit.


Battery is easily failed also.
The charging port is welded on the motherboard, thus replacement requires relatively high manual technique.  

A1989: From this model, mostly t2 issues. Hard to repair. Because models from A1989 hardly fail. As long as water seepage, mostly B+.
Its power supply chips are mixed up. Some A1989 power supply chip is cd3215c00z. Be aware of not mixing up the chips with a z, and without z. I have experienced on it. Strange that chip with z is without glue, while chip without z has glue.
Concerning t2, I don’t dealt with it a lot. Booster is normal, but no dimming. After boosting, current of single board is around 60mA, and accessible to dfu mode. These are generally due to a failed t2 firmware. You might refer to Apple official website and forums for maintenance method. Some booster is normal, but current is a bit higher, accessible to dfu mode. When you come across this, you can measure the resistance value of power supply circuit around hard disk.


A1990 and A1989 are similar. Seems the hard disk of A1990 is easy to burn out. I have not tried if it’d work after changing hard disk. Although it’s B+, but failed capacitance is mostly caused by dampness.


That’s all for my summary. There might be mistakes or omission, welcome to comment below. If you find it helpful, share with me below in the comment! Thank you.