Normally I'm pretty good at tracking down bouncing voltages due to shorts, SMC issues, etc, but this one has me stumped. Any help is much appreciated:
0. No liquid, board DID have a cracked Q7802 when I got it...replaced that first thing, before applying power to the board. Inspected rest of board very, very closely for damaged/missing components after seeing this. No other physical issues found.
1. ppbus_g3h 12.58v
2. pp3v42_g3h 3.43v
3. pp3v3_s5 bounces so quick multimeter can't catch it; initially found 3v3_s5 shorted (.000) which turned out to be U7200. Replaced U7200 and diode back up to around .100; I'm wondering if there's still a small short present? Good board is .120...I attribute this to discharge/etc.
4. SMC_PM_G2_EN bouncing as well, but my ppbus is 12.56 so I thought MAYBE damaged SMC, but replaced it and symptoms remain the exact same.
5. No shorts found after resolving the one on 3v3_s5; checked 3v3_s5-s0, 5v_s5-s0, vrtc, 1v5, 1v05, etc.
Usually I make enough headway to figure it out, but this one has me confused. Where else should I be looking for the cause of SMC_PM_G2_EN to be bouncing? I thought this was a power cycle, but the SMC is not resetting as my ppbus_g3h is stable, correct? My next steps were to see if 3v3_s5 killed any of the state switches (Q7810/30, etc), or Q7812? But if I'm going to blindly replace things, I'd much rather ask before doing so, to learn what to measure next, etc.
All help appreciated; not wanting to spend hours and hours on this one, so wanted to ask early. Thanks again! Really appreciate it.
0. No liquid, board DID have a cracked Q7802 when I got it...replaced that first thing, before applying power to the board. Inspected rest of board very, very closely for damaged/missing components after seeing this. No other physical issues found.
1. ppbus_g3h 12.58v
2. pp3v42_g3h 3.43v
3. pp3v3_s5 bounces so quick multimeter can't catch it; initially found 3v3_s5 shorted (.000) which turned out to be U7200. Replaced U7200 and diode back up to around .100; I'm wondering if there's still a small short present? Good board is .120...I attribute this to discharge/etc.
4. SMC_PM_G2_EN bouncing as well, but my ppbus is 12.56 so I thought MAYBE damaged SMC, but replaced it and symptoms remain the exact same.
5. No shorts found after resolving the one on 3v3_s5; checked 3v3_s5-s0, 5v_s5-s0, vrtc, 1v5, 1v05, etc.
Usually I make enough headway to figure it out, but this one has me confused. Where else should I be looking for the cause of SMC_PM_G2_EN to be bouncing? I thought this was a power cycle, but the SMC is not resetting as my ppbus_g3h is stable, correct? My next steps were to see if 3v3_s5 killed any of the state switches (Q7810/30, etc), or Q7812? But if I'm going to blindly replace things, I'd much rather ask before doing so, to learn what to measure next, etc.
All help appreciated; not wanting to spend hours and hours on this one, so wanted to ask early. Thanks again! Really appreciate it.
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