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Thanks JohnB8812. I have replaced all three chips. PPBUS is not shorted, however CPUVR_PHASE is reading 5 ohms. Does this sound normal? Or did I bridge a ground pad to a CPUVR_PHASE pad? I know certain lines around CPUs and GPUs typically have a low Resistance. But I just wanted a second opinion...

Thank you for the suggestion. That makes a lot of sense.

So a week has passed and the customer came back in with the same issue. It looks like the Microphone cable was indeed a red herring. At this point, it looks like the FDFMF6808 chips will need to be replaced. I did get 3 FDFMF6708 chips from DigiKey. I will follow up with the success of this repair.

It is a strange one, but that is what it is looking like. I told the customer to pick up as is and if issue comes back, then we will discuss board repair. Thanks for your input. Just in case, I am getting some FDFMF6708 chips from Digikey to keep in stock.

Thank you, JohnB8812. Before I called the client to give a final diagnosis, I noticed that someone has replaced the TopCase before. I removed the logic board to inspect if anything was suspicious, and I discovered that the Microphone cable was taped down with Kapton tape. Two thoughts went...

Thank you for your quick response. The client bought this computer second hand a few weeks ago, so I will see if they want to move forward with the repair. If so, I will purchase some FDMF6808 chips off of Mouser and follow up with how it went. Thank you.

I have an 820-3662 board that came in today for random shutdowns. After researching here on the forums, it looks like random shutdowns are a very common issue with this board and mostly pertain to a video issue. I am not sure if the issue with this computer is related or not but here are the...

Hi, 2informaticos.Thanks for getting back to me. I looked further into it and it appears that in most of the instances we have had where the built in microphone does not work, it is being recognized in System Report and works in Facetime, but does not work in PhotoBooth. I am still looking in to...

Couldn't really find the appropriate list to put this under but thought this was as close as it got. Something we've noticed lately, and wanted to see if anyone else did as well, was when we've been installing High Sierra it seems like the microphone no longer works. This has happened on...

Thanks. I am looking into to that now. I did make a discovery and noticed there was an issue with my MagSafe 2 cable that I have plugged into my DCPS. I replaced the MagSafe 2 cable and now I draw .025A upon connecting to board and spike to .400A for a split second, and drop back to .025A. With...

Sorry for the long delay. I did not have access to post on the forum for some reason, but I am back on now. I replaced U7501 and now the board will power on in SMC bypass mode will all rails present for a second then turn off, then power back on again after a few seconds, then power off again. I...

This is true. The board turns on in both normal and SMC bypass mode. I an smc from the exact same board. Twice just to be sure I didn't get a dud SMC. When installing a new bios, do I have to pair it to the ME first before testing, or can I swap one from the donor board just to see if it even posts?

I get fan spin and all power rails present. It originally slipped my mind to hook up board to a LVDS and see if it even posts. When i installed board back into macbook housing, and device has fan spin that restarts every 10 seconds. it appears it doesn't post or chime in SMC bypass mode. I've...

All the SMC sensors appear to be present. I plugged board into LVDS port and performed an SMC bypass, I get 1.8 on CPU VCORE, but no post. I am starting to think this may be a dead CPU.

I replaced the SMC again with another one from a donor board before I saw your replay 2informaticos. The board is still doing the same thing, so I am looking into the sensors, now. I have 3.3V on AVREF_SMC.

It took awhile to get an SMC stencil and 2 donor boards, but I went ahead and replaced the SMC, get green ling on magsafe and all S5 rails are present, but now device only turns in SMC bypass mode. All rails are present in SMC bypass mode. Does this mean the replacement SMC is a dud? If so, I...

R7520, R7521, R7522, R7544 are all measuring correct resistance. C7524 is not shorted. R7520, R7522= 2.35v P5VS3_EN = 2.9v

Yes, PP5V_S3 = 2.35V in SMC Bypass mode. In normal mode, there is no pulse, even after triggering SMC_ONOFF_L L7520 Diode Reading= 0.392v All measured in normal mode VD0R = 2.4v VP0R = 0v IP0R = 0.034v IPBR = 0.063v

Thank you for clarifying that for me. I had a feeling that is what I was dealing with, but I wasn't sure. Okay so I tried the SMC bypass and the board pulls 0.200 Amps from DCPS. Power rails are being pulled down. PP5V_S5=5v PP5V_S4 = 4.8v PP5V_S3 = 2.35v PP5V_S0 = 2.3v PP3V3_S5 = 3v PP3V3_S4 =...

Whoops, Did not mean to put PPVIN_S5=12. Apparently made up a reading.