Re: Need help with with macbook pro 820-3115-B
I don't believe it's shorted. I get 0.36v on [B]PP5V_SUS_FET[/B]. It's low, but there's still something there. I tried shorting the pins on [B]Q7840[/B], but still no joy. When I short the power button pin to ground (on keyboard connector), the fan jerks a bit. But that's it.Re: Need help with with macbook pro 820-3115-B
I don't believe it's shorted. I get 0.36v on [B]PP5V_SUS_FET[/B]. It's low, but there's still something there. I tried shorting the pins on [B]Q7840[/B], but still no joy. When I short the power button
MadMaxDog
Member
Last Activity: 04-23-2018, 07:42 AM
Joined: 02-08-2018
Location: Lisbon
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Re: Need help with with macbook pro 820-3115-B
Once again, Thank you [B]BlueMidnight[/B] for that detailed explanation.
As suggested, I measured around Q7840. Here's the result.
Looking at this, I'm getting two different results from 2 components that seem almost identical. If [B]Q7820[/B] is getting 0v on it's [I]Gate[/I] and outputting 3.31v from it's [I]Source[/I] to it's [I]Drain[/I], I figure [B]Q7840[/B], which also has 0v on it's [I]Gate[/I], should be similar, and should be outputting the 5v it has on [I]Source[/I].
...Leave a comment:
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Re: Need help with with macbook pro 820-3115-B
Ok, I have [B]good news[/B] and [B]bad news[/B], but first, let me apologise for the delay in posting. I just haven't had much time lately.
The good news is I have finally managed to get my hands on the [B]correct charger[/B], and I re-measured everything. So all measurements in Pink are brand new.
Bad news is [B]I haven't progressed anymore[/B], and because the new charger may have changed the values I feel I should start over from scratch.
I also have a few more *confusions* to sort out....Last edited by MadMaxDog; 03-27-2018, 06:59 PM.Leave a comment:
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Re: Need help with with macbook pro 820-3115-B
Thank you BlueMidnight. Your previous explanation made a lot of sense to me, and while we're at it, I have a certain confusion about the use of capacitors in certain places. I understand that capacitors filter out AC and are usually connected to ground as near as possible to sensitive chips to help stabilise the power. But in the schematics there are several places where capacitors are placed between two voltages. In this case, what exactly are they doing? If they only let AC through, are they simply letting the AC through from one...Leave a comment:
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Re: Need help with with macbook pro 820-3115-B
Sorry, I wasn't trying to be repetitive, (even though I do feel I'm going round in circles - something still escapes me).
I did read the explanation about the 10 second short, but, when you say: [B]That is normal. Resistance mode on your meter will send a tiny current through the circuit. It then measures voltage on each probe and uses Ohm's Law to figure out the resistance of the thing you are testing[/B] I don't understand why that short would go away after 10 seconds. if I remove the probes, turn off the multimeter, then back...Leave a comment:
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Re: Need help with with macbook pro 820-3115-B
Here's where I'm at now: [B]Still confused with the _L names[/B], and here's why:
See the image above? First I thought [B]U7941[/B] wasn't working, and that replacing it would fix my board, because it has voltages going in left and right, and nothing coming out on [B]P3V3S5_EN_L_R[/B] ([I]I can't find a datasheet for that bad boy[/I]). But now I'm not so sure anymore, since [B]P3V3S5_EN_L_R[/B] has an [B]_L[/B] in the name, is it supposed to be [B]LOW[/B]?
P.S. [COLOR="Red"]Red[/COLOR]...Leave a comment:
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Re: Need help with with macbook pro 820-3115-B
Another symptom, not sure I mentioned this before: right after I disconnect the charger, I get a short to ground on PPBUS_G3H. If I keep measuring, the multimeter will beep for 10 seconds then the short will go away. If I connect the charger again, then disconnect it, the short comes back for another 10 seconds.Leave a comment:
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Re: Need help with with macbook pro 820-3115-B
I just connected the charger again to re-test the voltage on all the power rails, and on the very first fuse in the system (F6905) I'm getting a fluctuation I didn't have before. It jumps from 14.0v to 14.7v, then back to 14.0v etc...
Anyone know what that's about?
EDIT: I'm getting all sorts of erratic behaviour now. Near R7011 which I just measured, I had 8.2v on one side and 1.2v on the other, then suddenly it went up. Now it measures 14.7v on one side and 3.4v on the other.Last edited by MadMaxDog; 03-01-2018, 12:07 PM.Leave a comment:
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Re: Need help with with macbook pro 820-3115-B
Here's another question I don't know quite how to phrase. To kill boredom I sometimes just put the multimeter in diode mode and go around measuring some caps for shorts (red probe on ground). Most caps will test ok, having one side with a good connection to ground and the other with none, but every once in a while, quite randomly, I get a very quick continuity beep from the multimeter when I first touch the cap's side that shouldn't be connected to ground, then the brief short goes away. (hope that made sense, it's the best I can explain...Leave a comment:
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Re: Need help with with macbook pro 820-3115-B
My main problem has been more of a logistical one. My girlfriend is constantly requiring the charger so she can watch movies on the projector with my macbook air, so I get stuck here just being able to measure resistors and shorts, and I get bored, so eventually I'm going to take something off then put it back again. It's quite hard to resist (get it? resist... resistor...) :P
I would like to use (or learn to use) the functional test points featured on page 7, but I don't quite understand them. I find it weird that they...Leave a comment:
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Re: Need help with with macbook pro 820-3115-B
I did. No CPUVCORE....Leave a comment:
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Re: Need help with with macbook pro 820-3115-B
I haven't had too much time to play around with it, but I do have some progress.
I removed 2 resistors that were testing at the wrong values, so I could test them off the board. They checked out so I put them back (R2156 & R5040).
The battery charging worked, so now I have a correct power source for testing. With battery connected (both with and without charger connected) I can get a 20 second fan spin by shorting Pin 5 of keyboard connector to ground (Thanks BlueMidnight). But no chime and fan stops after...Last edited by MadMaxDog; 02-27-2018, 09:29 PM.Leave a comment:
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Re: Need help with with macbook pro 820-3115-B
Thank you BlueMidnight, that clears quite a few doubts I had.
This makes more sense to me now.
Ah. This is where I was also getting confused about the name. I figured BATLOW *ONLY* referred to the battery, which is not even connected right now so it should always be low, right? (If LOW = TRUE, and the name 'BATLOW' implies "is_BATtery_ LOW?", with no battery connected I would expect the battery to be low, therefore no power on SMC_BATLOW_L makes perfect sense to me....Last edited by MadMaxDog; 02-25-2018, 02:28 PM.Leave a comment:
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Re: Need help with with macbook pro 820-3115-B
Funny how some pages are missing from the schematics pdf. I have found 3 different versions online and none of them have the SMC page.
Anyone got that page for an Apple 820-3115-B ?
I've been searching an old airport board for another 100k resistor to replace R5040 (I don't know, I just think I should try that). Found one, but while tweezer-transporting it to the macboook board, it jumped off into oblivion. That was the only micro-tiny-little-resistor I had (for 100k), the only other one I can find is about...Leave a comment:
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Re: Need help with with macbook pro 820-3115-B
New Info: I can get the board to start up by briefly shorting R5040 (that in my understanding is sending 3.3v into SMC_BATLOW_L), so I may be getting closer to the problem.
R5040 measures at 100.5 K, so I figure it's alright, but then again, if I have 3.3 volts on a line with a single 100k resistor, shouldn't I also have close to 3.3 on the other side? Could R5040 be the problem?Last edited by MadMaxDog; 02-23-2018, 08:42 PM.Leave a comment:
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Re: Need help with with macbook pro 820-3115-B
Wow, thanks for that detailed post.
Unfortunately I don't have another charger, nor do I have access to one, so I'm going to have to figure this out using this one. Did I mention it has worked 3 times? All I'm going for right now is a fan spin.
Would it be absolutely silly to inject a volt or two where SMC_BATLOW_L is supposed to be?
As you noticed, I have been struggling a bit with all the abbreviations. And this confuses me more... If the [B]_L[/B]'s are supposed to be low, why do I need...Leave a comment:
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Re: Need help with with macbook pro 820-3115-B
Took some more measurements and here's another image... [B]Q7840[/B] on [B]5V_SUS FET diagram[/B] doesn't seem right to me. Any thoughts? or does the 8/5 mean it's closed at 5 volts (4.8 in my case) and open at 8v ?Re: Need help with with macbook pro 820-3115-B
Took some more measurements and here's another image... [B]Q7840[/B] on [B]5V_SUS FET diagram[/B] doesn't seem right to me. Any thoughts? or does the 8/5 mean it's closed at 5 volts (4.8 in my case) and open at 8v ?Re: Need help with with macbook pro 820-3115-BLast edited by MadMaxDog; 02-22-2018, 04:52 PM.Leave a comment:
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Re: Need help with with macbook pro 820-3115-B
Ah, interesting... So U7941 might be fine after all... So in than case, what power is missing to get this going... SMC_S4_WAKESRC_EN maybe?
... So I see it comes out of U4900... Is this the time when I have to test all U4900 inputs? Or is there a better / smarter way to go?Last edited by MadMaxDog; 02-22-2018, 04:20 PM.Leave a comment:
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Re: Need help with with macbook pro 820-3115-B
Also, I forgot to mention, and it seems important to me: When plugged in, I hear a very faint and constant clicking sound. I have put my ear to it many times but it just sounds even all over the board (on both sides) and impossible to pinpoint (even tried a tube on my ear, cell phone microphone with a sound analizer app). It clicks about twice per second.Leave a comment:
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Need help with with macbook pro 820-3115-B
Hi All,
This is my first post. If you read my intro ([URL="https://www.badcaps.net/forum/showpost.php?p=806842&postcount=18590"]intro[/URL]) it will explain why I am here and asking these questions.
The skinny version is this:
- I am new to electronics and smd repairs.
- I have attempted to fix a [B]macbook pro 820-3115-B that has no Vcore, no fan, but has green light on charger[/B] (excellent condition, no liquid or any kind of damage whatsoever, and has never been fixed before).
- While probing around, [U]on...
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