Component Models
Battery: A1494
| Problem | Solution | |
|---|---|---|
| Random crashing | This is an incredibly common issue people will report, and 99% of the time, it is bad soldering on U8900 on 2012/early 2013 Machines. On late 2013 through 2015 devices, the issue is likely failing CPU MOSFETs. This has been confirmed with x-ray inspection. With failing CPU MOSFETs, people will report a black screen followed by a restart or shutdown. Kernel panics with failing CPU MOSFETs are very uncommon, and suggestive of another problem. The failing CPU MOSFETs can be replaced with FDMF 6708 or FDMF 3030 chips (FDMF6824C is also compatible) . DO NOT use FDMF 6808 chips from a donor board. TCRS Circuit explanation/repair | |
| No power, no power draw | Liquid damage to keyboard prevents machine turning on because power button integrated into keyboard, likely WS_KBD_ONOFF_L shorted to ground. If this is the case, it will power on with keyboard cable disconnected. | |
| No power, PPBUS_G3H 4v instead of 12.56 | U7100 ISL6259 bad, shorted current sense resistors R7121 & R7122 to ground through the U7100. | |
| No power, PPBUS_G3H shorted to ground. | Measure PPBUS_G3H to vCORE coils (coils around CPU/GPU) IF those measure UNDER 1Ohm (0.3-0.8) then you most likely have a direct 12V short to CPU/GPU. On this board this situation is always a no fix, since 12v fried the CPU. If PPBUS_G3H to CPU/GPU vcore coils is not under 1 ohm, the short is elsewhere, inject 1v and use thermal camera to help you find the short. Example: https://www.youtube.com/watch?v=m2IpCawa3wg (39Ohm short on PPBUS_G3H, GPU MOSFET's gone bad because GPU buck converter U8900 became desoldered from the board) | |
| No power, 24-25 ma taken |
| |
| No power, 168 ma taken |
| |
| No green light on charger |
Example: https://www.youtube.com/watch?v=O0sDWN0Pnio (Bad U7000, 2 broken resistors and broken DC in board + U8900 reflow to prevent future problems (often becomes desoldered on 820-3332 boards)) | |
| Battery not recognized | First, try a known good battery. If it doesn't work, check PPBUS_G3H - if it is 12.23v, the SMC is not communicating with the battery on its data line, either because the SMC is bad, or because the pullup resistors on the data line are bad. On rare occasion U7100 can pull down the data lines. There is a shared data line between the battery, SMC, and ISL6259(U7100). If PPBUS_G3H is 12.56v, then you probably have a bad battery. | |
| No backlight |
When you find that 5V is still missing on L8300 and LCD_PWR_EN is missing on U8300 - do not chase 99% of the time this turns out as a no fix - usually bad iGPU or MUX communication issues. | |
| No Power 250mA taken | 250mA Draw is often a sign that PPBUS_G3H is shorted to ground. Measure Voltage on PPBUS_G3H = 0V, not present. Measure resistance to ground of PPBUS_G3H = 0.008 ohms. PPBUS_G3H is shorted to ground. Measure resistance between PPBUS_G3H and CPU_CORE MOSFETS. 14.6 ohms PPBUS_G3H not shorted to CPU_VCORE. Inject 1V into PPBUS_G3H. Draws 5 amps. Owie test reveals Q7130 is hot. Q7130/Q7135 along with U7100 make up a buck converter that generates PPBU_G3H Measure PPBUS_G3H resistance to ground after removing Q7130/Q7135, and there is still a short. measures 6.6ohms now Measure PPBUS_G3H resistance to ground after removing U7100. measures 9.9ohms now. Inject voltage into PPBUS_G3H again, draws 25mA now. Short is gone. Replace Q7130/Q7135/U7100, because if Q7130 has failed short, then it will send 18V to the ISL6259(U7100) destroying it as well. (Replace as a set, otherwise you'll end up in a loop destroying parts) Apply power again. Back to drawing 250mA, and PPBUS_G3H is shorted again measuring 0.004ohms. Visual inspection reveals a solder bridge on U7100, Remove solder bridge, FANSPIN! https://www.youtube.com/watch?v=l9R9W_nuGvo&t=183s Example #2.... 268mA current draw, visual inspection reveals cracked tantalum capacitor was causing the short. Replacing the bad capacitor fixed the problem. https://www.youtube.com/watch?v=g85FqqkZiaE | |
| No Power - Draws 60 - 65mA | Possible corrosion on PPVRTC_G3H rail, check around C1910/C1531/C1532/C1533. Even though this is a low voltage rail, measuring a few kilo-ohms here is a problem. It should measure O.L. | |
| no image/ intermittent image |
| |
| Image & No Backlight | 5V going to LCD - LCD_PWR_EN & 0V going to Backlight Measure Fuse F770 - Should Be 13.3v Measure voltage Pin 6 on Mosfet Q7706 Measure voltage Pin 4 on Mosfet Q7706 - Should Be 13v Measure voltage Pin 3 on Mosfet Q7706 - Should be 12.4v Check R7702 should be 63.4k ohms Check Short To Ground on backlight rail after D7701 If 0.0v then unplug screen cable and check backlight rail for short again. Rail should have voltage. Most likely a damaged LCD backlight panel at this point Replace LCD Unit - Possible damage to LCD Backlight | |
| Turning on off on off (braindead) | Check for corrosion by PCH (Platform Controller Hub), reflow needed | |
| Will not run off of a known good battery, but can see the battery & identify its health within the operating system using coconutbatery | Check R7005 - if blown, PP3V42_G3H will not be present when running off the battery, but WILL be present when running off the charger. | |
Charger Green Light Flashes with battery connected. | Replace Q7130 |