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A1466 820-3437-b not turning on

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Biggtechman

Member
I stayed up fixing a ipad.
I just checked l7560 3.329 and its stable
just jumped r5116 for 10 seconds then turned board over to check PM_PWRBTN_L it's a stable 3.431
do you mean to jump it continuously until I've checked PM_PWRBTN_L ?
 
2informaticos

2informaticos

Administrator
Staff member
"PM_PWRBTN_L is stable 6.420v wile r5116 is shorted."
Really no idea how can you get such high voltage there.
And I repeat, you must only short R5115, or R5116, for 1s or even less; when the board is powered of course.
Is just like you press the power button. The pads of these resistors (which are not present on the board) are used to simulate power button.

"the short disappears after a few minutes of no power..
it comes straight back once mag is plugged in???"
Does this mean you measure continuity (diode mode), on powered board???
I hope you don't do it again.
In fact, wait 15-20s after power removed, before measure in diode mode.
Let time to discharge power rails...
 
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Biggtechman

Member
Ol got.
that high reading on PM_PWRBTN_L is that high when r5116 is shorted.
first reading was when I shorted r5116 for about 10 seconds then removed the short and checked PM_PWRBTN_L the reading was a stable 3.431
but it seems to be that all the time.
so it's like the shorting of r5116 to mimick power on button is not doing anything.
 
D

dukefawks

Administrator
The usual suspects should be inspected now. Corrosion on U1900/U1950 pin 8/J6100/U6100 and traces and resistors going to U6100.
 
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Biggtechman

Member
I have checked all the above mentioned ic's for corrosion ot signs of damage.
they all look fine and I've checked pin 8 and its corresponding chips for continuity and they test ok.
the only corrosion I found on the board was what I mentioned when I first posted this post.
r1663
r1661
r1669
they have no continuity to the test points that are really close.
the test points were so badly corroded I couldn't even run a jumper.
 
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Biggtechman

Member
Ok I have had a closer look at resistors around u6100 u1900 and it seems that r6101 and r2042 are no good.

r6101 is meant to be 3.3u says schematics but it reads 12.50 and r2042 reads 10.58

would this cause it not to turn on ?
 
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dukefawks

Administrator
12.50 what? K M Ohm? Are you measuring with power removed? The usual culprits are R6110-28 and traces between them
 
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Biggtechman

Member
I just noticed that c1031 is very dark.
I have another a1466 that come in for keyboard replacement, mind you its trolling me to...
not a fan of these a1466...
anyway c1031 on pin 1 is showing 80.1u in diode mode
and it seems to be showing a half short in continuity mode
 
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dukefawks

Administrator
I think you do not know how to use a multimeter. If you are measuring a resistor you measure across the resistor and on the Ohm scale.
Caps you can never measure in circuit if you wanted to measure capacity. On diode mode you would never get 80.1u. I really do not understand what you are trying to measure.
 
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Biggtechman

Member
Sorry, I have a lot to learn, and thanks to people like you I keep learning :)
in continuity it reads 80.1 and has a funny beep, l I'll ke half a short.
 
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Biggtechman

Member
Ok guys.
I've spent some time trying to figure out macbook boards.

here is some new findings.

so I'm gett in ng ppbus_3gh, pp3v4_3gh
I've checked for pp3v3_s0 on r1343 and I get 055.3mv
Pp1v05_s0 read 005.3mv on c7649
on pp5v_s0 I get 0v on j6100 pin 29, l4010 0v also.
does this help ?
any advice ot direction sims appreciated
also thanks again for your time and patience
 
2informaticos

2informaticos

Administrator
Staff member
Any voltage from _S4 to _S0 will appear after board starts.
Your board doesn't turn on, so post all _SUS and _S5 voltages you have...
 
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