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I'm trying to fix my broken Lenovo g500s laptop motherboard. There is no short circuit between Vin and GND, but it sucks around 3A from power supply. I found that branch marked red on my picture is shorted do GND. PQ307, PQ301 and PQ302 seems to be ok. Where to look now?
schematic:
http://www.mediafire.com/file/dqp8vda3adq43d8/LA9901PR10_DIS_0320.pdf
schematic
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>>1230380
check PR306 PQ307B
where do P2 and P3 pins lead too.
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>>1230390
also how did you test to determine that that net was shorted to ground?
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>>1230392
I used diode check in multimeter on pin 4 in PQ302 and GND test pad.
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>>1230390
>where do P2 and P3 pins lead too.
it looks like those are test points
>PQ307B
I just found out that PQ307A and B are in fact one device in 6 leg package.
when I try to apply red wire of multimeter to leg 3 and black one to 4 there is no connection as expected, but there is short between leg 1 (red) and 4. Is it fucked?
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>>1230430
oh, 4 and 1 are both connected to GND.
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>>1230432
ok, I removed PQ306 and it was damaged. PR306 gives me 20k and PR305 gives me 180k which I believe is close enough to declared 150k. Unfortunately circuit is still shorted to GND in the same net.
BTW, I hate this microscopic SMD bullshit.
Thread posts: 7
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Thread images: 3