[SOLVED]820-2936 No PP5V_S3 & PP3V3_S3

[Ryanlen2]

Computer came in with liquid damage. Board seems very clean so spill had to be minor. DC in board diode was burnt. I replaced diode on DC Inboard and logic board turned on and booted. Keyboard was also damaged. Would not get green light on charger and no fan with old keyboard installed. Replaced keyboard and everything was working for a while. Started to reinstall OSX and during at some point the board just started to cycle 1 fan spin continuously. PP5V_S3 is missing. PP3V3_S5 was there but was flaky. Now n missing as well and no spin at all. G3Hot 12.5V, PP3V42 3.42V, PPVINRTC 3.4V, PPBUS_S5_HS_Computing_ISNS 12.5V, PPDCIN 16.7V. Missing both enables on U7200. Pin 16 12.5 V.

Thank you.

 

[Ryanlen2]

Update - Q7221 pin 2 - 3.4V. Pin 6 - 0V. Pin 5 of Q7221 - 0V. Pin 3 - 0V. Replaced Q7221... no. Found Q7921 was smashed (not sure how that happened, I think it happened when tech was changing keyboard.) It too has been replaced.

Thanks.


Update 2 -

Replaced U7941. I now have PP3V3_S5_EN_L on pin 5 of Q7221 but 0V on pin 3? Shoudnt I have PP3V3_S5_ENTRIP now? Also missing SMC_PM_G2_EN on U7941 0V in Diode.

SMC time?

 

[dukefawks]

PP3V3_S5_EN_L The L means it should be low.
Is it getting a green light now? I suspect corrosion under SMC, give it a reflow.

 

[Ryanlen2]

Ok. Thanks for that. Yes, green light on. Already reflowed SMC. I guess I'll replace it? Have a good night man.

 

[dukefawks]

SMC_PM_G2_EN on U7941 0V in Diode. Are you saying a short to GND or just 0V there?

 

[Ryanlen2]

Shorting out to ground now with U7941. Might be bad chip/soldering because once I removed it no more short. Will get back. Thanks.

Have a good day.

Update - Replaced U7941. SMC_PM_G2_EN no short. .427 in diode. Still no fan spin.

 

[Ryanlen2]

Replaced SMC - same result


PP3v3_s5 .124 in diode. .001 in Voltage.

PP5V_S3 is .004 in diode.

SMC_PM_G2_EN 3.4V




Update - Replaced U7200. Now PP5V_S3 short is gone. I have .126 in diode for this. However now U7200 is getting super hot when plugged in to charger. Already replaced twice.

VREG5 is .004 in diode. (How the fuck did I get a short in PP5V_S5 now! LOL! UGH..)



Thank you!

 

[dukefawks]

If U7200 gets hot there is a short on one of the LDO outputs. So VREG5 is a good suspect here. There is not much on 5V_S5 line so this short should be easy to find.

 

[Ryanlen2]

Yeah. I ran into one of your other posts about U7200 issues. So I went ahead and looked at VREG5 and found short. Short was coming from U5805. Just curious... How do you think that happened? IDK... Just finished putting everything back and fan is now spinning. I will install board and run diags and hope for the best.

I'm no Genius, but something tells me there was an easier way to do this, if I wasn't half retarded and better understood the acronyms and functionality of some of these IC's in the schematic.

Thanks for your help. Later man. Have a good one.

 

[dukefawks]

I say this happened with you poking the pins of U7200 for testing. Look at what happens between pins 16 and 17....

 

[Ryanlen2]

Ok, Thank you.


So basicly I bridged pins 16 and 17 sending 12V to a 5V rail either with probing or possible shotty placement of U7200. This could probably have been solved by just replacing U7200 in the first place. But since I didnt realize I wasnt supposed to be getting voltage on ENTRIP pins I kept (frustratingly) messing around with it. Thank you for the informing me. I appreciate it.

1 more thing -

Computer is now running and passed diagnostics, but I notice a delay in chime from when I hear the optical drive power up. Like 3-4 seconds. Any thoughts?

 

[dukefawks]

You just got very lucky the board didn't totally fry. A slip like this with a probe can be absolutely fatal.

I see nothing wrong with the last question you had. Case closed.