No, that's not our method!
Ksansan
Member
Last Activity: 05-11-2023, 10:40 AM
Joined: 01-12-2022
Location: Lemmer
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Re: MacBook Pro A1990 doest turn on
No, that's not our method!
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Re: MacBook Pro A1990 doest turn on
I've got a damn power button that doesn't work.
That's bad!
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Re: MacBook Pro A1990 doest turn on
There should not be a short between pin 1 and pin 6.
It should be hundreds of ohms...Leave a comment:
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Re: MacBook Pro A1990 doest turn on
You can of course use capton, and that's a good solution, but you can take a piece of metal from a can and cover it with
If you mean the black cover on the laptop board itself, it's just a black material that looks like heavy paper, like a postcard....Last edited by Ksansan; 01-26-2022, 10:09 AM.Leave a comment:
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Re: MacBook Pro A1990 doest turn on
There is an ordinary piece of cardboard glued there that can be removed and put back on if necessary.
When you solder the chip, put a piece of thin iron over the cardboard to protect it from the hot air.
If you have never soldered such a chip before, practice on something unnecessary.
Sorry if I got in the wrong question....
Last edited by Ksansan; 01-26-2022, 05:12 AM.Leave a comment:
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Re: MacBook Pro A1990 doest turn on
I will be following your struggle with interest!
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Re: MacBook Pro A1990 doest turn on
Happy ending!
Mon2 Thank you so much,
Your help is invaluable, I definitely couldn't have done it without it!
The most amazing thing about this story is that it took a 90 amp current pulse to burn this capacitor!
It's unbelievable, but it's true.
And what is even stranger is that the R5620 resistor is still alive!
There is no error in the current, I measured it with a pliers.
I can't remember, where was this rubber band?...Leave a comment:
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Re: MacBook Pro A1990 doest turn on
Thanks for the tip, really enough capacitors there!
No short, that's for sure, I can see a normal semiconductor wiretap.
I will be able to try it only tomorrow.Leave a comment:
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Re: MacBook Pro A1990 doest turn on
Hi!
I have news: the capacitor C9081 was shorted.
But to find it, I had to raise the voltage to 4.5 volts.
I hope I didn't burn anything, because the operating voltage is 12 volts.
It will take a couple of days to find a small ceramic for 10 microfarads.
Then I'll try to turn the laptop on....Last edited by Ksansan; 01-21-2022, 02:58 PM.Leave a comment:
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Re: MacBook Pro A1990 doest turn on
Honestly, I am stumped.
All the coil terminals are called to ground with a resistance of 1.4 to 500 ohms,
And the resistance on the input terminals of the board is 0.0014 ohms, which is a couple of orders of magnitude less.
It is obvious that none of the coils can be the source of this short circuit.
Does anyone else have any ideas?Leave a comment:
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Re: MacBook Pro A1990 doest turn on
I shortened the wires, connected the common wire to two points to distribute the current, and raised the voltage to 0.9 volts. As a result, the current increased to 10 amps, but there is still no heat,
At the same time the voltage at the input to the board, only 14 millivolts, with a current of 10 amps!
I think the capacitor is not capable of making such a strong short circuit.
Anyway, I don't have any good ideas yet.
Very much short-circuited 0,014v:10a=0,0014ohm...
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Re: MacBook Pro A1990 doest turn on
Good afternoon! The results are as follows:
UPD: The same results for QB701...Last edited by Ksansan; 01-19-2022, 08:48 AM.Leave a comment:
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Re: MacBook Pro A1990 doest turn on
Hi!
F7000-F7001 fuses have 24 amps, so I think the current can be increased.
But of course I would like to hear the opinion mon2
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Re: MacBook Pro A1990 doest turn on
Some advice.
When I connect a 0.8 volt current source, the voltage drops to 0.005 volt with a current of 4.1 amps.
Apparently I have a complete short circuit.
All capacitors have the same 0.005volt.
I think the capacitor will not give that much of a short.
I connect the plus to the fuse, the minus to the common wire.
Apparently because the short circuit is so strong, nothing gets hot.
Which way should I go next?
Increase the current to 10 amps?
Won't the copper tracks...Leave a comment:
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Re: MacBook Pro A1990 doest turn on
Is the resistance suspiciously low?
All other coils on the board have resistances well over 100 ohms, I think they are serviceable.
I connect 0.8 volt to the top pad of the fuses (where the short circuit is).
Minus to the common bus.
When the voltage is applied, I see 4 amps of current, wait 3-4 minutes, no element is obviously heated.
There is 12.27 volts on pin 1 of the fuse....Leave a comment:
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Re: MacBook Pro A1990 doest turn on
The computer was working fine, was turned off by closing the lid.
And a few days later, it just wouldn't turn on.
I haven't found any traces of moisture anywhere yet.
I found a 0.8V 3A power supply.
Thanks for the video, I will study it, and then I will torture my board
��Leave a comment:
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Re: MacBook Pro A1990 doest turn on
I found a voltage source of 1.2 volts. Is that a lot? I can limit the current to any value.Leave a comment:
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Re: MacBook Pro A1990 doest turn on
Thank you for your help! Went over the board, all capacitors on this bus have a short.
Soldered off 2 fuses, short to the common wire circled in red. Went looking for a regulated current source....Leave a comment:
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Re: MacBook Pro A1990 doest turn on
Greetings, I'm new here, sorry if anything is wrong.
I have the same problem, the A1990 stopped turning on.
The 3 capacitor in the red circle have a resistance of 1.0 ohm, is this normal?
I don't have a wiring diagram yet, so please help with advice....Leave a comment:
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