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Problem: hp laptop problems
Machine: HP G6000(same mainboard as V6000) Laptop will not power up The machine has been water damaged. It does not have system standby power, which are 3V and 5V.
Check Max8724(the battery charging chip) first, because to make system has standby power this chip must work correctly.
This is a 28 pin chip, we only need to test 1, 2, 4, 8, 10, 11 pin. They are VIN(main power for chip), LDO(provide 3.3V for chip itself
in order to set REF voltage, also provide signal to drive 2 MOS to charge battery), REF(set reference voltage of the chip),
SHDN#(enable/disable chip, a switch), ACIN(indicate the power supply has plugged in), ACOK#(power adaptor ok with mainboard).
Everything ok except 10 pin, ACIN is 0V.
This is incorrect, mainboard doesn’t detect there is an adaptor! Trace it backward and find it is very simple – mainboard use 2
resistors to pull the input voltage(19V, directly from dc socket) down to about 4V, so test the first resistor and find it opened.
Change it and 3V/5V power come up and mainboard be able to switch on. Then the trouble start when I try to charge the battery.
The charging current never go beyond 0.15A and after 10 seconds the charging light start to flashing. Also can’t switch on from battery.
First, change Max8724, still same problem. Next check all the resistors around max8724 and change it if it has any sign of watering,
still no good. Then change KB3926(EC/KBC, chip monitors the statue of battery), still same. This is the fault that I never dealt with before.
Decide to check MBDATA and MBCLCK, 2 signals that send battery information from battery to KB3926 before I give up.
I find the MBDATA is short! Finally, find there are 2 pins stick together on CN10(the connector of multimedia switch board).
Fix it and it start to charging battery. Switch on with power adaptor, ok.
Remove the power adaptor once switch on, battery keep the mainboard running, ok.
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