MacBook Pro A1707 Not turning on, PPBUS G3H shorted to ground repair

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Revision as of 15:35, 29 October 2023 by ASRepairs (talk | contribs) (Created page with "{{stub}} {{Repair Guide |Device= |Affects parts= |Needs equipment= |Type= |Difficulty= }} ==Problem description== <nowiki>#</nowiki>incomplete thumb|Example image (Figure 1) -- No image yet. Help expand this page by uploading it! ==Symptoms== *sub 20 ohms on PPBUS_G3H *Not turning on ==Solution== How to find short circuits Inject 1 V (increase if no reaction), watch for hot spots with thermal cam. Usually it's a bad tantalum cap on the...")
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MacBook Pro A1707 Not turning on, PPBUS G3H shorted to ground repair
Device
Affects part(s)
Needs equipment
Difficulty
Type


Problem description

#incomplete

Example image (Figure 1) -- No image yet. Help expand this page by uploading it!

Symptoms

  • sub 20 ohms on PPBUS_G3H
  • Not turning on

Solution

How to find short circuits

Inject 1 V (increase if no reaction), watch for hot spots with thermal cam. Usually it's a bad tantalum cap on the PPBUS_G3H rail.

Example video (Taking 20 V, 0 A. Ethanol used instead of thermal cam with 0.8 V on PPBUS_G3H, resistance between PPBUS_G3H and CPU coil is 3.6 Ω) Example 2: https://www.youtube.com/watch?v=TZsvvUWUInE (Taking 20 V, 20 mA. Bad capacitor located via visual inspection)

Read the resistance from PPBUS_G3H to Vcore coils (coils around CPU/GPU) IF those measure UNDER 1 Ω (0.3–0.8) then you most likely have a direct 12 V short to CPU/GPU. On this board this situation is always a no fix.

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