Had an 820-3476-A that wasn't detecting the battery and had loads of green crap around the J0705 area. Customer decided to buy a replacement battery and plug that in without cleaning any of the corrosion! Anyway I ultrasonically cleaned the board and still had no battery detection and would not run off battery. Let me tell you the story of where I am at the moment:
Being a repair monkey I replaced U7100 - no change. D7050 -no change. R5380 and 5381 (which looked good and measured fine) - no change but I now had 3.4V on SMBUS_SMC_5_G3_SCL which was at 2V before (should have checked for that!). Finally I was out of options and replaced the SMC - I now had battery detection, charges battery and ran off battery fine. But I had no trackpad or keyboard at all in OS mode!
Tried known good trackpad and keyboard - no change. Found SMCBUS_2_S3_SCL was at 1.5V. Replaced R5370, R5371 (again they measured OK) and get 3.3V on SMCBUS_2_S3_SCL - but now I get no chime and video output.
Put back original SMC which would POST originally- no change still no chime or video output.
Specifically the fan spins, then off, then on permanently. Before this happened the fan would remain on constantly then chime.
The CPU gets warm but not hot - in typing this out (always helps me think things through) I've realised I get 2.5V on PP3V3_S4. I get 3.3V on PP3V3_S4SW_SNS.
My next thought was to just replace any resistor or capacitor around the SMC that has PP3V3_S4 running to it since the whole issue from the start seems to be SMC related. Is this a good plan or is there any common thing I should check for you would recommend?
Thanks
Jon
Being a repair monkey I replaced U7100 - no change. D7050 -no change. R5380 and 5381 (which looked good and measured fine) - no change but I now had 3.4V on SMBUS_SMC_5_G3_SCL which was at 2V before (should have checked for that!). Finally I was out of options and replaced the SMC - I now had battery detection, charges battery and ran off battery fine. But I had no trackpad or keyboard at all in OS mode!
Tried known good trackpad and keyboard - no change. Found SMCBUS_2_S3_SCL was at 1.5V. Replaced R5370, R5371 (again they measured OK) and get 3.3V on SMCBUS_2_S3_SCL - but now I get no chime and video output.
Put back original SMC which would POST originally- no change still no chime or video output.
Specifically the fan spins, then off, then on permanently. Before this happened the fan would remain on constantly then chime.
The CPU gets warm but not hot - in typing this out (always helps me think things through) I've realised I get 2.5V on PP3V3_S4. I get 3.3V on PP3V3_S4SW_SNS.
My next thought was to just replace any resistor or capacitor around the SMC that has PP3V3_S4 running to it since the whole issue from the start seems to be SMC related. Is this a good plan or is there any common thing I should check for you would recommend?
Thanks
Jon
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If anyone is interested in my reasoning I had 1.3V on PM_PCH_PWROK instead of 3.4V. All should be good now thanks can mark this as solved. Again most of my posts are me just talking to myself but it forces me to think correctly and hopefully will help someone else out there having a similar issue