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Electronics => Repair => Topic started by: leham on October 17, 2015, 05:06:16 am

Title: Repairing a macbook PCB - Is this a bad idea?
Post by: leham on October 17, 2015, 05:06:16 am
hi guys,
recently picked up a a1181 macbook with a K36b motherboard..
Mainboard was dead but still charging.

Bought a replacement board, system boots, see's battery but says "battery not charging", if the battery is dead or not in (with the charger in), the system won't boot..

Constant Green LED on the charger cable, when the system is on, Orange if I plug it in when off (does not charge)

PCB is clean, no water damage and can't see any thing visibly wrong, all the fuses are ok..

I have a schematic for the system, I don't know what I should look for in there..

I have a crazy idea to bodge it back together...

Seeing as the battery is working and has it's own built in protection. Could I just install a 11~12v switching regulator (amp or two), running off the 16v input from the charger, directly to the battery terminals inside the system...?????

Battery specs:
Lithium
10.8v @59wh (or 59 "ebay-watthours") or  5400 mah (I think I calculated that right)....

System can read the battery, so I'm guessing the serial portion of it's working.
I can fully charge the battery with the dead PCB


Also every one of this model I've found online has crud on the RAM, I think it's the plating on the DIMM's reacting with the metal in the RAM slots...

(https://pbs.twimg.com/media/CP46rXXU8AADM9N.jpg)

Thanks for any help :)


EDIT: after looking deeper the not charging board has no 12 rail
Title: Re: Repairing a macbook PCB - Is this a bad idea?
Post by: Rasz on October 17, 2015, 09:54:10 am
you have pcb that charges for comparison - start there

measure charging inverter, check feedback resistors, fuse
Title: Re: Repairing a macbook PCB - Is this a bad idea?
Post by: LA7SJA on October 17, 2015, 10:09:01 am
I have found a lot of interesting tips on repairing apple mainboard. https://www.youtube.com/user/rossmanngroup (https://www.youtube.com/user/rossmanngroup)

Johan-Fredrik
Title: Re: Repairing a macbook PCB - Is this a bad idea?
Post by: crispy_tofu on October 17, 2015, 10:14:11 am
Quote from: leham on October 17, 2015, 05:06:16 am
Also every one of this model I've found online has crud on the RAM, I think it's the plating on the DIMM's reacting with the metal in the RAM slots...

(https://pbs.twimg.com/media/CP46rXXU8AADM9N.jpg)

That's weird ... don't RAM sticks usually have gold plating?
Title: Re: Repairing a macbook PCB - Is this a bad idea?
Post by: poot36 on October 18, 2015, 06:00:17 am
I have only seen ram sticks have that happen to them when there has been liquid damage that has got inside the connector.  Try cleaning the entire board with IPA or better yet a ultrasonic bath.  As for the totally dead board what does it do if you do a SMC reset on it?  The one where you hold down the power button right shift key and I think another key.  You can find schematics online for these boards so you can start your trouble shooting with the correct voltages been applied to the components.  On the board that won't charge the battery also try disconnecting the battery meter gas gauge and see if it starts chargeing.
Title: Re: Repairing a macbook PCB - Is this a bad idea?
Post by: crispy_tofu on October 18, 2015, 06:13:17 am
Quote from: poot36 on October 18, 2015, 06:00:17 am
As for the totally dead board what does it do if you do a SMC reset on it?  The one where you hold down the power button right shift key and I think another key.

I believe the A1181 Macbook is the thermoplastic one that has a removable battery, so the steps for resetting the SMC are slightly different than the ones with non-removable batteries:

Source: https://support.apple.com/en-au/HT201295

Good luck OP! We used to use the same Macbooks at school, I (personally) love them  ^-^