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820-3115 Does Not Regognize Battery

H

handydandy1971

New member
Hi Guys, I have a 2012 A1278 (820-3115) That had Very slight Water Damage around the Q5480 and R5481 Area. After Cleaning the area It still Had No Green Light so I Replaced U7000 and Now it Runs Perfectly Off the Charger But does not recognize Battery and there is no orange Light...I checked the Board For any Corrosion under the Microscope and all looks good...I am also Getting 12.23v at F7040 wIth adapter Present and 11.98v With just the Battery...3.4V on both Pin1 and 2 of L6995...I also removed C6400 and C6405...I am Getting 0.4v resistance between Pins 17/18 on U7000...So far I have Replaced...U7000, Q7035, R6990, D6990, U6990, And R5087...Any ideas?...Thank You
 
J

jadao

Member
Pin 17-18 0.04 ohms between them, it looks like your pins are shorting together, make sure U7000 is properly soldered and check again resistance between pins 17-18. It should be close to 2.2-4.5ohms.

If U7000 doesn't run well it will not output SMC_BC_ACOK (CHGR_ACOK) and this will prevent light on magsafe even if you have 3.42V on L6995.

12,23V instead of 12,60V with charger is an indication that smc is not running because it's bad or because U7000 is not sending required signals to smc.

U7000 is talking with smc, if data lines are messed it will not recognize battery. (See page 48)

Could be also crap Under SMC but I would first adress U7000 for magsafe light and correct reading on pins 17-18.
 
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D

dukefawks

Administrator
Check diode mode on both data pins to the battery SMBUS_BATT_SCL and SDA.

Battery indicator disconnected to rule out that is giving issues? R5280/81 checked?
 
H

handydandy1971

New member
Replaced U7000 Again and I am getting 3.4ohms on Pin 17/18 now...I have a Green Light on Charger But it Still is not recognizing the Battery and I am still getting 12.26v On F7040 with Charger attatched and 11.98v with Just the Battery attached. I Also removed the Rubber Around the Corners of the SMC Chip Cleaned all around the perimeter the Fluxed and heated the SMC...I measured SMBUS_BATT_CSL and SDA lines and get 2.39 in Diode Mode...R5281/80 giving Proper Mesurements also. Also I did replace R5087 Prior to getting a Green Light with a resistor that is 470k 5% 1/16w 220 instead of a 1/20w as that was all I had...Could that make a Difference on not seeing the Battery? And last but not least I have Not put C6409 and C6405 Back on the Board yet JUST IN CASE they were the reason for not getting a green light in the beginning...The computer Runs Great off the Charger But still no Battery...I feel like I'm SO CLOSE!!!..lol...Anything else I can try?. Thank You in advance for Your Help. :)
 
D

dukefawks

Administrator
2.39 is not a diode mode measurement. It will in normal cases never be over 1.0. Typical measurement is somewhere between 0.300 and 0.700 for data lines.
I'm pretty sure your SMC is dead.
 
H

handydandy1971

New member
Thank Tou for the Quick Response Duke :) With the Red Probe on ground and Black probe on Pin 4, Pin 6 of the Battery Connector I get 2.399kohms on each pin with the Multimeter set to Diode Mode?
 
Gurmon

Gurmon

Member
You're measuring voltage drop in diode mode, so it cant be the figure stated in ohms.

Anyway, replace the SMC.
 
H

handydandy1971

New member
Is there anywhere that I can Pirchase a Preballed SMC for this model? I don't have a stencil of Balls...InDO have another 820-3115 Board but I can't renal the SMC chip once I remove it...
 
D

dukefawks

Administrator
Forget about "new" SMCs. Take one from a donor board and reball it. Get the stencil and practice on a few trash SMCs. Use search on the forum there is a link to the Ebay auction for the stencil somewhere.
 
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