Repairing a macbook PCB - Is this a bad idea?

[leham]

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...



Thanks for any help


EDIT: after looking deeper the not charging board has no 12 rail

[Rasz]

you have pcb that charges for comparison - start there

measure charging inverter, check feedback resistors, fuse

[LA7SJA]

I have found a lot of interesting tips on repairing apple mainboard. https://www.youtube.com/user/rossmanngroup

Johan-Fredrik

[crispy_tofu]

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...

That's weird ... don't RAM sticks usually have gold plating?

[poot36]

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.

[crispy_tofu]

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:

• Shut down the computer.
• Disconnect the MagSafe power adapter from the computer if it's connected.
• Remove the battery.
• Press and hold the power button for five seconds.
• Release the power button.
• Reconnect the battery and MagSafe power adapter.
• Press the power button to turn on the computer.

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

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