Working on this 820-3115 board that had some "rough" handling by someone prior to me getting it. Replaced ~10 components that were broken-off/missing (mostly non-critical caps/resistors, etc). Confirmed all parts are now present on the board, but I can't restore power, with the following symptoms:
1. Board has ppbus_g3h, pp3v42_g3h, ppvrtc_g3h, pp5v_s5 all present and stable/normal, but pp3v3_s5 is 0v.
2. Pin 6 of U7200 is .8v, which I believe is normal, but pin 23 is 0v.
3. PP5v_s5 is present and stable, despite pin 23 of U7200 not being present (this confuses me).
4. SMC_PM_G2_EN is present and stable (3.45v)
5. Charger light is solid green the entire time, but it flickers ever so slightly, as if it's trying to power on. All SMC power lines stable/normal.
6. No shorts on pp3v3_s5, ppbus_g3h, pp3v42_g3h or pp5v_s5
7. Replaced U7200 (twice--three total chips), U7941 and Q7221, no change
I'm not sure where to go from here. All help appreciated--thanks!
1. Board has ppbus_g3h, pp3v42_g3h, ppvrtc_g3h, pp5v_s5 all present and stable/normal, but pp3v3_s5 is 0v.
2. Pin 6 of U7200 is .8v, which I believe is normal, but pin 23 is 0v.
3. PP5v_s5 is present and stable, despite pin 23 of U7200 not being present (this confuses me).
4. SMC_PM_G2_EN is present and stable (3.45v)
5. Charger light is solid green the entire time, but it flickers ever so slightly, as if it's trying to power on. All SMC power lines stable/normal.
6. No shorts on pp3v3_s5, ppbus_g3h, pp3v42_g3h or pp5v_s5
7. Replaced U7200 (twice--three total chips), U7941 and Q7221, no change
I'm not sure where to go from here. All help appreciated--thanks!
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