How to replace the CMOS / PRAM supercapacitor by battery?
As some of you may have read my previous MiniDisplay Port doesn't work; one chip stays warm during sleep.. I got a water-damaged MBP where an unknown chip stays active and hot during sleep. It discharges the battery much faster than it would do otherwise, but the other problem I discovered is that time and date settings are lost and reset to 2008, presumably because the main battery is too drained to maintain the Is there no CMOS RAM battery on this model?'s charge. Even if the machine is set to use Apple's NTP servers to sync back the time, having the wrong date means certificates are not recognized, and that wither the browser or Mac OS X refuse connection on invalidity grounds, preventing time to be set properly. An annoying catch-22.
According to the only shop that does this kind of repair, replacing the burned chip is just too dangerous for the computer to be worth it, on an otherwise working machine. It's a 40-pin QFN package, very close to other tiny components.
The other option would be to replace the supercapacitor powering the MBPs without a removable battery by a standard 3V battery to power the PRAM and SMC, and add a physical switch to disconnect the main battery while hibernating. Sounds like a less risky alternative as only two solder points on the board would be required.
The question would be: where is the supercap holding the charge for the PRAM and SMC on a Late 2011 MBP?
An update on an old thread: the main battery is now at 3.4% capacity and I am, again, at a crossroad. I suspect the few times I left it sleeping while forgetting to plug it in took their toll by draining the battery further than it could recover from.
The RTC chip (Silego SLG3NB148V) CAN be powered by a 3V coin battery through pin 13 (page 26 of the board schematic: match with similar part Silego SLG3NB114, page 11), it just isn't installed, and no provision is made on the board for such a battery. The "chip that doesn't sleep" is U9310, and marked as "Critical" on the schematic. What does that mean exactly? That it can't simply be removed and have the computer still working?
I found one mail-in repair service in Tennessee that claims to do "most"repairs between $75 and $125US, but still unsure if they would do mine as I'm far away from their shop.
To get the laptop back in proper working order, I'd be looking at a rather hefty bill:
replacement battery $80
repair existing motherboard: between $100 and $400, depending on shop and custom fees.
swap faulty motherboard for one taken from a Mid-2012 A1278 model in order to gain performance (Swap USB 2.0 for USB 3.0). I checked, they are screw-compatible. $500+, more so if I'm unlucky with customs.
And maybe get about $60 back selling the current faulty board?