Hi good Friends., today working on a Macbook Pro A2289, Logic board 820-01978-A. The history was liquid spill, Cleaned & replaced all corroded components & now the logic board shows 20v & .01amp on the meter. Not taking in any amps. Upon trouble shooting I get the required stable voltages 5V, PP3V3_G3H 3.3V but no PP3V3_S5. Checked the schematic, assume that this is generated from U7800. Checked all the Input/Output voltages on this chip. All is fine, except PP3V3_S5 is missing. Resistance from GND to PP3V3_S5 is 146 Kohms. First I need to make sure whether PP3V3_S5 is generated from this chip??? Thanks in advance
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What is the exact voltage to ground of PPBUS_G3H @ F7000? -
PPBUS_G3H @ F7000 = 12.61V (no fluctuations at all)... Do you think that this logic board has gone into DFU or Recovery mode as it's Pulling ~0.03-0.06A current at 20v from USB-C as measured by USBC meterLast edited by mferna14; 06-08-2025, 12:13 PM.Comment
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It could be but personally cannot keep up with the madness of each model as it varies with the direction of the wind. THIS model does require a charged battery to boot. Would you have a battery connected? Ghettoware.
reference:
https://boards.rossmanngroup.com/thr...harging.64804/
See post # 10.Comment
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Ok mon2., at last I figured out ths problem. This laptop had to be put in DFU mode & all restored back to factory default. Now at least I will remember that with 20V & drawing 0.03 ~ 0.08 amp, mostly it is to be rectified with DFU Mode. & one thing more for these models logic boards PP3V3_S5 will be missing & once restored all the require point with have 3.3V. Case done. Thanks dear for your helpComment
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