Good day folks. I've been struggling with this Samsung laptop for a while now and I decided to take a break and ask for some help, since I can't figure out what's wrong with it. The board is a PRAHA_SRE REV 1.1 board. I managed to find a schematic, but no boardview, so if anyone has one and would like to share it, it would be greatly appreciated.
Here's the deal: the laptop's totally dead - no power, no LEDs, not nothing.
To make the story a bit shorter, I thought I managed to isolate the problem to the Super I/O (KBC ?) IC in the pictures. It is a H8S/2110B. The reason I thought it was the issue is because if you look at the power sequence on page 3 of the manual I attached, the S5/S4 rails on the left are all present, but I can't get into the S3 state, in other words KBC3_SUSPWRON doesn't go high and since that signal is supposed to come from the KBC, I assumed it's faulty and proceeded to finding a replacement. I found some on Aliexpress and ordered 3 of them, though I didn't actually do any research beforehand to know whether these require any sort of programming, which leads us to today when I finally got around to replacing it. The operation was annoying to say the least: took a VERY long time to finally get a new one on there. It was a bit of a disaster all throughout: I knocked some of the neighboring parts off when the chip finally came loose and I failed to pull it up with my tweezers and instead it slipped sideways. Fortunately, I had the forethought to take a picture of the area and only a cap and a resistor moved, so I managed to put them back. My repair didn't work unfortunately: same exact problem as before: no power at all.
I wasn't satisfied with the job I did on that chip: it wasn't quite lined up properly, maybe some of the pads weren't touching the pins, since I was a bit too ambitious to solder it back with my hot air station rather than using the soldering iron to drag-solder, so I thought the extra heat had an unwanted effect on it too, so I ended up removing the replacement chip and replacing it again, this time using my iron all throughout. The picture shows the last chip after I soldered it.....looks decent enough if I may say so myself and the pins appear to be soldered correctly. I inspected it up close as much as I could with my magnifier, since I don't have a microscope and crossed my fingers: still nothing......at this point I was pulling my hair out and not having any other choice (other than to maybe try and waste my third and final IC), I thought I'd take some measurements again to see if anything has changed. Same story as before: I'm stuck in S5/S4, with no KBC_SUSPWRON.
There's another thing I noticed: no 3.3v on the power switch either ! If you follow the line KBC3_PWRSW, it should lead you to page 43 where the buttons SW2 and SW1 are. SW2 is the power key and SW1 the other button next to it which I don't care about at this point. If you follow KBC3_PWRSW some more, it will take you to page 40 to the right of the KBC (U10) where there's a pull-up resistor, R251, pulling the line up to MICOM_3.3v. The power rail is present, but that KBC3_PWRSW is not pulled high, so something's definitely not right there. Unfortunately I have no way of finding out where R251 could possibly be located, hence why a boardview would be required in such cases, since there's too many resistors to measure by hand. Annoyingly enough, the other button SW1 HAS 3.3v on it, but it doesn't do anything either ! There's no short to GND on the PWRSW line, though if I try to jump 3.3v from the button next to it, it goes low, so it's like there's a short somewhere on that line....
I'm not sure what to try next....does that KBC chip require programming ? This was the fatal flaw of this repair attempt: not knowing whether a "blank" chip could work on there. Is there a way to program it to get it going ?!
Speaking of which, this might explain why there's no power on that pin: if it's like the controller on an Arduino board, the pin could be configured to be LOW, hence why it pulls the line to GND and stays that way....just a thought to further push this board towards the trash bin
Here's the deal: the laptop's totally dead - no power, no LEDs, not nothing.
To make the story a bit shorter, I thought I managed to isolate the problem to the Super I/O (KBC ?) IC in the pictures. It is a H8S/2110B. The reason I thought it was the issue is because if you look at the power sequence on page 3 of the manual I attached, the S5/S4 rails on the left are all present, but I can't get into the S3 state, in other words KBC3_SUSPWRON doesn't go high and since that signal is supposed to come from the KBC, I assumed it's faulty and proceeded to finding a replacement. I found some on Aliexpress and ordered 3 of them, though I didn't actually do any research beforehand to know whether these require any sort of programming, which leads us to today when I finally got around to replacing it. The operation was annoying to say the least: took a VERY long time to finally get a new one on there. It was a bit of a disaster all throughout: I knocked some of the neighboring parts off when the chip finally came loose and I failed to pull it up with my tweezers and instead it slipped sideways. Fortunately, I had the forethought to take a picture of the area and only a cap and a resistor moved, so I managed to put them back. My repair didn't work unfortunately: same exact problem as before: no power at all.
I wasn't satisfied with the job I did on that chip: it wasn't quite lined up properly, maybe some of the pads weren't touching the pins, since I was a bit too ambitious to solder it back with my hot air station rather than using the soldering iron to drag-solder, so I thought the extra heat had an unwanted effect on it too, so I ended up removing the replacement chip and replacing it again, this time using my iron all throughout. The picture shows the last chip after I soldered it.....looks decent enough if I may say so myself and the pins appear to be soldered correctly. I inspected it up close as much as I could with my magnifier, since I don't have a microscope and crossed my fingers: still nothing......at this point I was pulling my hair out and not having any other choice (other than to maybe try and waste my third and final IC), I thought I'd take some measurements again to see if anything has changed. Same story as before: I'm stuck in S5/S4, with no KBC_SUSPWRON.
There's another thing I noticed: no 3.3v on the power switch either ! If you follow the line KBC3_PWRSW, it should lead you to page 43 where the buttons SW2 and SW1 are. SW2 is the power key and SW1 the other button next to it which I don't care about at this point. If you follow KBC3_PWRSW some more, it will take you to page 40 to the right of the KBC (U10) where there's a pull-up resistor, R251, pulling the line up to MICOM_3.3v. The power rail is present, but that KBC3_PWRSW is not pulled high, so something's definitely not right there. Unfortunately I have no way of finding out where R251 could possibly be located, hence why a boardview would be required in such cases, since there's too many resistors to measure by hand. Annoyingly enough, the other button SW1 HAS 3.3v on it, but it doesn't do anything either ! There's no short to GND on the PWRSW line, though if I try to jump 3.3v from the button next to it, it goes low, so it's like there's a short somewhere on that line....
I'm not sure what to try next....does that KBC chip require programming ? This was the fatal flaw of this repair attempt: not knowing whether a "blank" chip could work on there. Is there a way to program it to get it going ?!
Speaking of which, this might explain why there's no power on that pin: if it's like the controller on an Arduino board, the pin could be configured to be LOW, hence why it pulls the line to GND and stays that way....just a thought to further push this board towards the trash bin
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