MacBook Pro 15" Mid-2014 (DG) A-820-3787 fan FULL SPEED & ASD IHSC Sensor error?!

[rigway]

Hi Everyone! : )
Apologise if something is not upto standard straight away, this is my first post. Hope it might not only be useful to me. I came across a similar thread - https://www.badcaps.net/forum/showth...highlight=IHSC
with a similar description but that wasn't helpful.

Situation:
Got a Apple MacBook Pro 15-Inch "Core i7" 2.5 Mid-2014 (DG), this is a unit with discrete/separate Graphics GT 750M. S/N: C02NK14CG3QP, Logic board model: A-820-3787. Issue I'm having with it - is after booting to OS FANs kick in at full blast. Software is eliminated as tried to run off external SSD and done complete fresh reset with Catalina = fault still present.

Have checked it with running ASD diagnostics with a result:
Sensor Failure=[Current (IHSC) -- Thunderbolt] Failed Value=0.383789
ERROR -- 2[Sensor reading above alarm point] -- TEST FAILED.

Fairly clean logic board, I've cleaned it with Isopropyl Alcohol, checked Thunderbolt area to see maybe I can identify a possible component, which would the this IHSC Sensor but had no luck yet. Maybe someone knowledgeable about those Mid-2014 MBPs had similar issues? Basically everything is fine with board/the rest apart from this sensor somewhere... It's not slow or anything like that, no limp mode, works great but is on crazy MAX FAN RPMs while running.

Got the boardview logic board schematic for it. Which component I need to look for on the board? OK with desoldering micro stuff, got fresh microscope sitting and waiting in case necessary as well. Attaching ASD log screenshot and sensor temps, which doesn't reveal anything suspicions. Lost a bit with diagnostics on it now..

Bought this logic board for spares to replace another completely dead one with liquid damage and having this now with a fresh one.. luckyI guess. Bought it with someone claiming that it's booting, can't argue about it : ) Both logic boards are A-820-3787, so I have all I need in case pulling replacing components is necessary. Any gudu here who might have at least any clue what to try - would highly appreciate your help ; )

Many Thanks in advance!

[piernov]

Re: MacBook Pro 15" Mid-2014 (DG) A-820-3787 fan FULL SPEED & ASD IHSC Sensor error?!

Only error when continuing on errors? No screenshot attached.

Open schematics PDF, Ctrl+F "IHSC".

[rigway]

Re: MacBook Pro 15" Mid-2014 (DG) A-820-3787 fan FULL SPEED & ASD IHSC Sensor error?!

Hi,

Here are my screenshots, this with the Sensor error. Regarding searching IHSC for components obviously I did it - nothing comes on.

What to check? Any advice

[SMDFlea]

Re: MacBook Pro 15" Mid-2014 (DG) A-820-3787 fan FULL SPEED & ASD IHSC Sensor error?!

Hi,

Here are my screenshots, this with the Sensor error. Regarding searching IHSC for components obviously I did it - nothing comes on.

What to check? Any advice

Search in the schematic PDF,not the boardview https://www.badcaps.net/forum/showthread.php?t=62268

[Askic]

Re: MacBook Pro 15" Mid-2014 (DG) A-820-3787 fan FULL SPEED & ASD IHSC Sensor error?!

This is current sensing and not temperature sensing issue. You need to check the corresponding resistors and whether the output capacitor is short circuited. Please, closesly examine the area (you can find it using the boardview) for any traces of corrosion or missing components.

[rigway]

Re: MacBook Pro 15" Mid-2014 (DG) A-820-3787 fan FULL SPEED & ASD IHSC Sensor error?!

Really Appreciate your replies! Honestly.. glad to be here and feeling that you guys decided to check and share your experience is just so meaningful!

I will be coming back to this board during next week and will post update so this story keeps developing for the benefit of same issues solving and future reference to somebody stumbling across anything similar if not exactly same.

I was dumb enough to think that IHSC will be some component but hey!, work and learn. Will be paying attention more to PDFs diagrams for future

Thing is this logicboard, which I got for replacement didn't had any corrosion, inspected it thoroughly before coming to conclusion that I need help with it. Very clean and in good condition. Interesting fact is that when I started testing it - usually doing it via Mini-DP cable to DP external screen, which I have for tests (with disconnected Retina display obviously, getting spare machines with knackered Retina Lids frequently).. tried both ports and there was NO video signal. Usually when were checking other numeros Mid-2014, Mid-2015 MacBook boards this way - they were always displaying straight away to external monitor.

This one refused from both ports. Later when I've put Retina LCD on it - booted/displayed straight away. Once booted - then it displays OK to secondary screen (weird I thought), this was quite strange to me.. Later followed this fresh discovery about IHSC/MAX FAN RPMS after it warms up.

I worked a lot on iMacs 2009-upto 2017 so far. So all this cycle of sensor loops is familiar to me in overall design idea. It's just "Panicking" and I need to calm it down ; )

[rigway]

Re: MacBook Pro 15" Mid-2014 (DG) A-820-3787 fan FULL SPEED & ASD IHSC Sensor error?!

Only error when continuing on errors? No screenshot attached.

When submitted first message and used "Insert Image" button.

I got my links which I made for this purpose externally:
https://ibb.co/n8JcZt7
https://ibb.co/0GSWStT
https://ibb.co/qs6LC21

Result was: [tralalaIMG]https://ibb.co/n8JcZt7[tralala/IMG] in text field..

Should have used BBcode full, there you go! : )

Now it works for me ; )

P.S. Very valid comment.

[rigway]

Re: MacBook Pro 15" Mid-2014 (DG) A-820-3787 fan FULL SPEED & ASD IHSC Sensor error?!

Hi,

Wanted to update with situation and close this thread. Issue resolved, however rather unexpectedly in a different way.

With good intentions I didn't want to use original SSD with data while doing testing. Had a spare 128GB SSD from iMac, which has exactly same connection and was detecting and allowing MacOS install without issues (except FAN panic obviously). When I had it plugged in all those sensor problems were present. As soon as I plugged in original 256GB SSD for those models it all went to normal: no error on ASD, no FAN panic. Macbook returned with replaced logicboard and repair finished. Bizzare but fact that apparently it was reacting this way to another SSD from iMac. Something that I was surprised to find out later on. Only error when continuing on errors.

Good thing that I haven't decided to ripping/replacing components in IHSC circuit - that would be fun to realize later ; )) Lucky decided to have a go with few more tests before that. Dismissed and many thanks for your replies, lesson learned.