Re: 820-3435 No power / light
Thanks piernov!
Yep, i don't have that equipment yet. Though I enjoy DIY and fixing things and would like to have them for any future repairs so i'll probably get them and try it out....
lebronballer
Member
Last Activity: 04-24-2020, 09:02 AM
Joined: 04-02-2020
Location: cincinnati, OH
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Re: 820-3435 No power / light
Resistance on the resistors look right.
Pin 1 at c7091 in diode mode shows 0.343v. Can't get a reading on the corroded pin 6 of u7090. Guessing that connection is messed up even after I've cleaned it with alcohol.
Do you have to use hot air to do the replacement or can you use a soldering iron for this?...Leave a comment:
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Re: 820-3435 No power / light
So i measure 14.9V at the testpoint next to pin 6 U7090. Pin 6 is the one that had corrosion on U7090 and i either dont get a reading on the actual chip, or i cant get the probe right on it so i was using the test point in the image attached.
i have 14.9-15v at R7005. I have ~0.7V at R7006 and it keeps dropping over time (maybe to 0, down to 0.4v now)....Leave a comment:
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Re: 820-3435 No power / light
Isn't that originating at U7090? Since i have both the PPVIN_G3H_P3V42G3H & P3V42G3H_SHDN_L coming to the testpoints before pins 6 & 8 there?...Leave a comment:
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Re: 820-3435 No power / light
Nope, nothing coming out of U7090. I measured PP3v42_G3H at L7095 and got nothing (0.1mV)....Leave a comment:
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Re: 820-3435 No power / light
Either i cant get the multimeter probes on pin 6/8 or they arent getting a reading, but i do measure 14.9v on both the test points leading to pin 6 and 8 right next to them (P3V42G3H_SHDN_L & PPVIN_G3H_P3V42G3H).
Do you think first try to heat it up to pull it off and clean then put it back, then replace it if that doesn't work?...Leave a comment:
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Re: 820-3435 No power / light
Thanks.
On L7095- 0.1mV on both sides, 82.5kohm both sides.
On F7140- I get OL on both sides resistance to ground. And voltage with MagSafe plugged in was 0.7V and continuously dropping.
I also have 14.9v on c7090 /c7091 pin 1.
Does this suggest it's just u7090 that's either bad or not making a connection (must stilll have corrosion)?...Leave a comment:
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820-3435 No power / light
Mac Air had a few drops of water spilled on keyboard. I opened it and saw slight corrosion on U7090. So far only cleaned it with a brush and alcohol.
Measuring voltages Here's what i'm seeing:
PPDCIN_G3H is giving me 15v (though it cycles between 14.9 to 15.0)
I also get 15v at the magport and dcin on the board, and also at PP18V5_DCIN_ISOL_R.
I thought those were supposed to be 18.5V?
Also, on PPBUS_G3H i only get 3mV @ R7006 which i think should be 8.6V?
Any ideas where to check next? I'm a beginner, so appreciate all...Last edited by lebronballer; 04-05-2020, 09:30 AM. -
Re: 820-2855 a macbook air 11
did you ever find the brd file?...Leave a comment:
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Re: New Members - please post your introductions here
Hi All, im an engineer from Ohio looking to learn about circuits and hopefully repair my own!Leave a comment:
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