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820-3115-B - Need to hold down power button to turn on

Antonio

Antonio

New member
First post on this forum, so excuse me if I leave something important out. Checked a bunch of other posts and didn't see anything related to this, so....

I have a mid 2012 board that only turns on if you hold the power button down. I'll get a small fan spin from a click, but in order to get it to do anything more I have to hold it down till it's nearly completely booted. I can boot off battery and the power cord both individually, and together. Being plugged in without the battery in results in me having to hold the power through the 5 light "where's your battery" thing, as well as the rest of the boot.
After it actually boots, it works, but EXTREMELY slowly.
As far as i'm aware nothing has been spilled on this computer, but I did get it off eBay, so, something was probably spilled on it...

I ran the ASD and it failed at IPBR

Sensor - Current (IPBR) -- Charger BMON (Prod) (test 1) - Sensor Range Reads Within Operating Range
- Check to ensure sensor reads within operating range.
ERROR - Sensor is reading above the high limit
- T E S T F A I L E D -


Andddd that's about where I got to.

I've already ran the board through an ultrasonic cleaning, but other than that i'm pretty much lost. My initial thought was that I wasn't getting ENOUGH voltage considering it was running so slow, but I'm new to this so everything I think is wrong anyway. Oh well.


Anyone have any tips? I do have all the tools required to do any of the repairs, along with donor boards for parts, but I don't have a schematic or board viewing software yet, so any components you mention if you coulda sorta just... "this thing, it's in the top like 2 inches of the board", that'd help me greatly. I should be able to figure out where everything is if I have a general idea of where the component is.

Thanks in advance!
 
A

aprendiz

Moderator
Check sense resistors R7050, R7051 and R7052, make sure that all traces that connect this components with ISL are ok...
 
Antonio

Antonio

New member
Oh, woah, I don't know how I completely missed that area. There's about 6 corroded pads and a few resistors around there that are all sketchy looking. Thanks for the help! Not gonna be able to attempt to fix it tonight, but nice to know I at least have a place to look now haha.
 
Antonio

Antonio

New member
No Title

Yeah, the whole area is just kinda shit in general. Is this SMC the same specs on an older board? I have lots of 2010-2009 ones I can take things from, but unfortunately this is the only one of this exact type I have left.
 

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Antonio

Antonio

New member
Replaced r7051 and r7052. Measured 13-14ish ohms from pins 17 and 18. I'm not 100% sure if that's accurate since the tips of my multimeter are shit, so i'm not going to attempt measuring the other set until I figure something out or get the tip extender things.

What should I be getting from 17-18 on u7000? After replacing those two resistors the computer is turning on (thank god), but it's still having the same problem, so that pretty much rules that out :/
 
Antonio

Antonio

New member
I get 3.3 ohm when I measure at each end of c7050. Pins 17 and 18 wind up going there, so I figured it'd be easier to get my shitty multimeter to touch that than the pins themselves. I'm pretty new to this, so if that's just the resistance of c7050 itself and not what the SMC would be getting, feel free to make sure I know i'm stupid so I can learn lol.

I'll try to figure out something to measure at the pins tomorrow.
 
george-a

george-a

Member
(sorry for jumping your thread Antonio - question opportunity!!!) Louis could you also explain how can ISL send 16V to SMC? And how can we test if that happened?
 
A

aprendiz

Moderator
Antonio check if there is continuity from pin 1 of R7051 to pin 18 of ISL and same for R7052 to pin 17, could be a broken trace...

george-a ISL does not send that voltage to SMC, otherwhise SMC would be fried..... ISL read sense resistors and report the results to SMC through I2C ( SMBUS_CHGR_SCL and SMBUS_CHGR_CKL pins )
 
Antonio

Antonio

New member
I can't seem to get good contact with any of the pins on U7000. There's a bunch of sticky leftover flux crap that I can't seem to get out of this area, which is blocking me from making sold enough contact with anything to measure properly through. Any tips to clean it up? Q tips just rip apart and leave me with an even messier area, so i'm not gonna try that again :p
 
Antonio

Antonio

New member
FIXED IT!

No 100% CPU usage, turns on right away, runs off battery, ect.

The problem was the broken trace. I just kinda swiped over all the pins on that side to get em separated then tried my best to get some solder down to that other pad pin 18 connects to.

Plugged it in and it turned right on! Gonna run ASD on it to make sure this wasn't the only problem though.





Anyway, thank you guys all so much for your help! This is the first board i've ever successfully repaired. Literally never thought i'd get to the point I could do this. I'll make sure to update everyone if my house starts on fire after leaving the computer alone for a bit.
 
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