Board Number: 820-00138
| Problem | Solution |
|---|---|
| Random crashing | 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. DO NOT use FDMF 6808 chips from a donor board. TCRS Circuit explanation/repair |
| No power, Liquid damage | If there is corrosion in the U7200 area it is not a good idea to connect the charger because there is a chance that it will send 12V to the CPU and kill it (or the CPU is dead already). Best to repair the corroded area(s) before connecting the machine to a power source. |
| 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 of bad capacitor: https://www.youtube.com/watch?v=rPMyN_BUgLA (Taking 0.2A. Ethanol used instead of thermal cam with 0.7V on PPBUS_G3H, resistance between PPBUS_G3H and CPU coil is 22Ohm) 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, PPBUS_G3H 4v instead of 12.56 | U7100 ISL6259 bad, shorted current sense resistors R7121 & R7122 to ground through the U7100. Example on 820-00426: https://www.youtube.com/watch?v=YC8q7GJ3vK8 Resistors were bad and the ISL6259 was bad too. Light on charger was on. |
| No power, 24-25 ma taken |
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| No power, 168 ma taken |
|
| No green light on charger |
Example: https://www.youtube.com/watch?v=izQ6X78yy84 (65mA on charger, "Few KiloOhms" short to ground on PPVRTC_G3H caused by corroded capacitors) Ppbus g3h 12.56v, green/orange ligh dimming, fan spin and then bat low symbol when plugged in charger cable, then check traces from Adapter Sense to U7000. |
| 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 | Make sure the issue is no backlight, and not no image!
If the screen is shorting the backlight to ground, you can fix the screen if the cap/connector on the screen is bad, it just sucks to do. But it is the only option since this screen is no longer available. |
| No image |
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.
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| Display does not turn off when closed |
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| 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. |
| Webcam not working | Bad R5677 |
| Thunderbolt not detected, liquid damage to port | Check Q8000 |