820-2915 ,battery "X" not being detected, not the simple cases usually encountered

[roy.ruan]

820-2915 ,battery "X" not being detected, not the simple cases usually encountered

Hi guys,having a strange 820-2915 board giving me headache.

problem is battery not being detected, thought should be a piece of cake as fixed a lot previously already.
usually only 3 things , which all had been checked in this case.


so here is the details,

problem is on SMBUS_SMC_BSA_SDA which only has 2.5v, thought would be either isl , bill connector or smc pulling the voltage down.

I check the ground resistance on pin1 of r5280 and r5281 before I did any replacements, so pin 1 r5280 is 610 , pin 1 on r5281 is 497

good board would have 400 something on both

I already thought it strange at that point, since usually the ground resistance would be pulled down, not higher



so what happened next was, SMC, ISL both got replaced. bill connector removed. d6950 replaced. c6952 replaced.

then same result. same ground resistance, same 2.5v (roughly)


so really have no idea what it can be, i checked the trace too, but they don't seem to be broken

any ideas?

 

[smiba]

Resistance of R5280/81 in Ohms? Are your ground resistance measurements in Diode mode or in Ohms?

Tried a known good battery?

 

[supamodz]

Check your smbus data lines with an oscilloscope. Your multimeter is to slow see if your data line is communicating with pulses.

 

[roy.ruan]

Diode mode,good battery for sure,tested

 

[dukefawks]

One last possible option is corrosion in/under the battery connector or another bad SMC. R5280/81 checked too?

 

[roy.ruan]

r5280 and r5281 were checked. don't see anything on the connector. but even I removed the SMC, the diode mode to ground resistance is still not right .

still 600+ on SMBUS_SMC_BSA_SDA

normal should be 400+