Typical "AC-IN" circuit on laptops - how does this work ?
Good day folks. Today I was messing around with a dead HP laptop which has sat in the shop for more than a year now, having various parts taken out of it, so I decided to dust it off and see what's actually wrong with it. It had liquid damage and it's totally dead. At this point I'm not actually asking for help on how to repair this, because I reckon it's not worth the time/money and there are too many fired components on that board....I contributed to that myself - read on to see what happened 
I'm curious about the power input circuit I've come across on many laptops and is also the place to start when it's completely dead or shuts off the AC adapter. It seems to be similar in design across many units, with slight alterations, but to my shame I can't quite follow how it operates. I have trouble following those "tags" - you know, when rather than drawing the whole "wire" because it doesn't fit, they draw a line and put a tag near it which corresponds to some other component which could be pages away. When I try going back and forth like this, I often lose it Literally
So this Pavilion DV6 has THIS board in it. It is totally dead after some soda was spilled on it or whatever. There are some components which are visually burned, but I was hoping it'd still be salvageable, especially since I had the schematic and all components were labeled, so that was of big help. I started at the adapter input, at the very beginning. Check out page 37 where the AC inlet is. So: power comes in through PL7 and PL9 into transistor PQ24. I got 19v after PQ24 so I assumed that part works fine. Then it arrives at PQ48 and this is where it stopped - nothing out the other side....actually there WAS something out the other side (where PC79 is) but it was only 10-12v and it seemed to fluctuate, meaning PQ48 was not "on". This is where I can't quite follow what's supposed to be happening....how is PQ48 supposed to turn on ?
PQ49 is on the right side of the page and it looks to me like it "selects" the battery as the power supply, while PQ48 selects the adapter as the power supply. Whichever is on, it goes through PR231 resistor to the rest of the buck converters and junk....
Here's where I screwed up: I tried jumping PG48 to bypass it and PU4 went up in smoke. From what I can tell, it generates 1.5v. It's got a hole in it now, so it's done for. Also I believe the ITE chip (SMC ?) got damaged too because I felt that part of the board getting slightly warm and it's now got a hint of a hole in it too....NOT GOOD...plus you also have to deal with what got damaged in the first place and all of those charred components....I don't think it's worth it....
I'm curious about the power input circuit I've come across on many laptops and is also the place to start when it's completely dead or shuts off the AC adapter. It seems to be similar in design across many units, with slight alterations, but to my shame I can't quite follow how it operates. I have trouble following those "tags" - you know, when rather than drawing the whole "wire" because it doesn't fit, they draw a line and put a tag near it which corresponds to some other component which could be pages away. When I try going back and forth like this, I often lose it
Literally So this Pavilion DV6 has THIS board in it. It is totally dead after some soda was spilled on it or whatever. There are some components which are visually burned, but I was hoping it'd still be salvageable, especially since I had the schematic and all components were labeled, so that was of big help. I started at the adapter input, at the very beginning. Check out page 37 where the AC inlet is. So: power comes in through PL7 and PL9 into transistor PQ24. I got 19v after PQ24 so I assumed that part works fine. Then it arrives at PQ48 and this is where it stopped - nothing out the other side....actually there WAS something out the other side (where PC79 is) but it was only 10-12v and it seemed to fluctuate, meaning PQ48 was not "on". This is where I can't quite follow what's supposed to be happening....how is PQ48 supposed to turn on ?
PQ49 is on the right side of the page and it looks to me like it "selects" the battery as the power supply, while PQ48 selects the adapter as the power supply. Whichever is on, it goes through PR231 resistor to the rest of the buck converters and junk....
Here's where I screwed up: I tried jumping PG48 to bypass it and PU4 went up in smoke. From what I can tell, it generates 1.5v. It's got a hole in it now, so it's done for. Also I believe the ITE chip (SMC ?) got damaged too because I felt that part of the board getting slightly warm and it's now got a hint of a hole in it too....NOT GOOD...plus you also have to deal with what got damaged in the first place and all of those charred components....I don't think it's worth it....
