BQ24738h - not charging - HP Model G7BJ - dag7bjmb8c0 Rev. C

[wnt2fx]

Hello dear tech freaks :-)

can i have your thought on this one ? I have no clue. In lack of schematics I used HP 15-p DAY11AMB6E0 for orientation in the BQ24738H area. I have no experience with this power IC.


The machine had a full short on +vin, caused by a dropped screw in the owners attempt to replace the battery. After removing the biggest among 4 small caps on that line, right at the input of PQ36 the machine was working again.

Everything seemed to work and after a while of testing I noticed that pq36/pq37 were reaching about 130C. One of them, I don't remember right and its not perfectly precise anyway with my IR cam. I think pq36. I watched a half minute too long and the machine died. I made no further testing and replaced both mosfets only. They were burned in and very hard to get off, particularly pq36. I finally managed and replaced them. Next the machine did work on dcin and on battery together but did fake charge, orange led and windows status but no amps. Now, after replacing 3 times pq36, 37 and BQ24738H all together the machine does not boot / shuts off as soon battery and dcin are connected both.Charging LED normal (white/orange) It runs on either but not on both. PQ39 seems fine and the resistors before the BQ on ACPRES, ACDET and ILIM seem fine too.

thanks !


if thats unreadable sorry, I attached it as jpeg. Also let me know if you need the schematics I used.

BQ24738H pin dcin dcin+bat bat


ACN 1 19,45 11,2 11,2
ACP 2 19,45 11,2 11,2
CMSRC 3 19,42 0 0
ACDRV 4 25,5 0 0
ACPRES 5 2,97 2,97 0

ACDET 6 2,62 2,86 - 2,88 0,88
IOUT 7 0 0 0
SDA 8 3,29 3,62 3,17
SCL 9 3,29 3,62 3,17
ILIM 10 1,016 1,006 1,006

BATDRV 11 3,08 17,3 17,3
SRN 12 3,07 11,2 11,2
SRP 13 3,07 11,2 11,2
GND 14 0 0 0
LODRV 15 0 0 0

REGN 16 5,98 5,98 5,98
BTST 17 5,8 10,9 10,9
HIDRV 18 3,07 11,2 11,2
PHASE 19 3,07 11,2 11,2
VCC 20 18,83 18,76 10,6

[mon2]

Re: BQ24738h - not charging - HP Model G7BJ - dag7bjmb8c0 Rev. C

Suggest to remove all power. Meter in resistance mode.

Confirm the resistance across each mosfet to be sure it is not shorting.

Source (1-2-3) & Drain (5-6-7-8)
Source (1-2-3) & gate (4)
Gate (4) & Drain (5-6-7-8)

Post each measurement. A low resistance is not good on a mosfet but resistance is futile.

Review the usual DCin mosfets as well as the battery mosfet (that enables only when the adapter is missing).

The shared voltage readings look very good

[mcplslg123]

Re: BQ24738h - not charging - HP Model G7BJ - dag7bjmb8c0 Rev. C

Battery discharge fet is very likely shorted/leaky.