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820-4924 wont charge battery intermittent green light

TCRScircuit

TCRScircuit

Super Moderator
Staff member
Something is obviously pulling down PP3v42... Look at U7001. Do you have ACOK on pins 1 and 2 and do you have ACOK VCC on pin 4? See if something is messed up there. Maybe U7001 is pulling down 3v42 and causing your no green light issue. Don't know how that would be related to your battery issue though but worth checking.
 
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Gannons3

New member
so i went back to the computer after i saw your message and plugged in the charger to measure what you suggested, and what do you know i get a green light??? this thing is weird. i still dont get the green light with the battery in so i suppose ill move on to that for now
 
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Gannons3

New member
so i noticed that when green lights working, i get 7.2v on pp3v42boost. but when its not i only get 6.7v possibly something wrong with boost/sense curcuit?
 
TCRScircuit

TCRScircuit

Super Moderator
Staff member
Could be something wrong in the boost/sense circuit, but now sense you lost green light did you loose 3.42? While the green light is not working, what is resistance to gnd compared to when the green light is working. Basically what I mean is catch the system when the light isn't on, unplug it, take a resistance measurement on pp3v42 and then catch it while the light is different and measure again. Compare the measurements. I have had these issues like this from a SMC acting funny and if the SMC was bad that could explain why 3v42 is being pulled down but DON"T touch the SMC yet.
 
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Gannons3

New member
when the green light is off, 3v42 sits around 3v when its on its right where its supposed to be 3.42. resistance to ground with light off is 25.8k with light on it is the same as far as i can tell im not 100% sure though.
 
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Gannons3

New member
this board is acting up something crazy. with no green light sometimes i get 3v on dcin sometimes i get the right 16.5 but then the 16.5 doesnt make it between d7005 and u7090. but then other times still the voltage will make it but ill only get 3v on 3v42 then sometimes it will give a green light and everything will be fine. it makes it hard to even explain whats happening because almost every time i post something, something else will happen differently.
 
TCRScircuit

TCRScircuit

Super Moderator
Staff member
I don't know.. Intermittent faults like this are never fun. Maybe corrosion under the SMC.. Look under it with the scope.. If it looks like something got under it give it a reflow.
 
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dukefawks

Administrator
I doubt the SMC is bad, there is a partial short on 3V42. This can pretty much be any cap on this line. It could be crap under the SMC too of course. In any case this one is going to suck.
 
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Gannons3

New member
I replaced the smc, there was a bunch of junk under the old one. I now get a green light whenever the battery is unplugged. if its plugged in i wont get a green light. and dc in will drop to 8.6v. im still getting 3.4v on pp3v42 though. nothing on smc_bc_acok
 
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Gannons3

New member
shouldnt be an issue on the acok line. i get a green light if the battery isnt connected to the board. its when it is connected i dont get the green light. dc in voltage is only 8.5v with the battery in.
 
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Gannons3

New member
so for some reason ive discovered that if i put my meter in diode mode and touch the top of Q7180 with red and put black on ground itll spike up to 16.5v and ill get a green light, the battery will start charging. dc in will stay at 16v where its supposed to be, but ppbus_g3h will be at ~12v. not sure if this helps determine the problem at all
 
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dukefawks

Administrator
I ask again: R5187 checked? ACOK should be present when the charger is plugged in with or without battery connected.
What is voltage on R7120 with and without battery? Charger connected of course.
 
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Gannons3

New member
replaced Q7180 solved the charging issue. but now the keyboard and trackpad dont work... wth..... im getting 3v3s4 and 3v42 on both U4830 and U4820
 
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