Extra info: U8130, a Ti TPS8308, is a Delay Supervisor Circuit. It ensures that PP3V3_SUS has come online and stabilised before the PCH fires up. PM_RSMRST_L is the signal it uses to give the PCH the thumbs-up.
Go back to 34:25, microscope view, pause the video, and check discoloration of left side mid pcb chip pad. There you are. Chip was ok, but electrolysis and/or corrosion has separated the chip from the pcb. You could just re-flow, but better be sure. Worth the trouble. Right?
Great to see the process of tracking down the actual cause an illusive fault rather than a shrug and replace the whole thing which seems to be common these days.
hi Paul, I'm thinking of taking my laptop diagnosis and repairs to the next level and adding this kind of testing, and hopefully fixing, but as a first step just finding out why things are dead. For example, I have a Dell Vostro 15 3568 that is "dead". Would an experienced person such as yourself think "I can diagnose that with my software and I can get the schematics for that" or is it a whole other world of pain for Dell, Lenovo, Toshiba etc? I'm not asking about financial return, just possibility/probability of just being able to do this kind of diagnosis or not based on if the info is available or not. Thanks 🙂
@@miff227 biggest cause of time loss tends to be when trying to work out a new machine; sadly when fixing PC laptops it's rare to happen across the same model more than a couple of times in a few years (unless it's a notable signature fault, like the old A300 Toshiba laptops and similar with the TOKIN caps ). There'll always be a percentage of machines you can fix without schem/BV, but by acquiring things like FlexBV and the matching files for a given board, you can increase that percentage, of course, it also means more rabbit holes to fall down too.
Nice video, good diagnosis. In case you're curious, the TPS3808 is a _microprocessor voltage supervisor_ IC from Texas Instruments. It's factory trimmed for a particular threshold voltage (G33 on the part indicates that it is for 3.3V) and when that sensed voltage dips below the reference, it will generate a reset output for a programmed (via external components) delay period. Also has a manual reset input (MR). I typically classify these types of chips as "brownout detectors", they can also be used to ensure that the attached CPU stays in reset until the monitored voltage rail becomes high enough to be reliably used. So several purposes, but you got the jist of it in your guess. Cheers,
Put the board into a plastic bag (eg. ziplock) with the solution you need inside of the bag. Then put the bag into the tray and the (existing) water bath. I allows you to choose a different cleaning solution without having to change the current one in the cleaner. And saves a bit on the amount of cleaner used. Ultrasonics should travel through the medium (main solution) and into the bags solution, maybe some loss through the plastic? I believe glass containers work better but hard to get a bigger board into one. Cheers,
Impressive reading and understanding of the schematics and board view. Great to see how you are developing as an engineer and your clear explanations are proof that getting your hands dirty pays off in the end.
Another very enjoyable and educational video mate. Perfect timing as well as I'm working on one of these at this moment, however this one has a different fault. Still good to learn a bit more about how it works.
The into brings about alot of memories.i remember 2year ago when i had an interest in board repair.everything I've learnt it's through this channel...keep up the good work graham
Excellent repair and fault finding process along with schematics. Appreciate all the hard work that went into making this video for us to learn and enjoy.
By skillful you don't mean the half-ass baked solder job where he left the replacement chip crooked on the board? With the slightest effort he could pull it straight, but no... yanking parts 'cold' of the board without any flux, thereby pulling almost a pad in order to finish it off with a crooked placed replacement.... what a joke. My OCD goes beserk, i'm going to unsubscribe from this kind of amateurism....
Brilliant fix and nice logical approach. Just goes to show that with the right approach and even if you don't specifically know what the faulty part does it can still be determined as faulty. One of my favourites from you dude. Keep up the awesome work.
Thanks Graham, great video, exemplary troubleshooting. Learned again also in FlexBV which I highly recommend. Greetings from Switzerland on the beautiful Lake Constance. Franco
Great video Graham. Very detailed detective work. I would think there is also a chance that a corroded pull-up resistor, R8133, could contribute to the fault. With all the Coke on the board, would you recommend replacing the keyboard?
Yea, I should've checked the pull-up resistor as it was right there, but lucky for me it wasn't the issue anyway. I don't think liquid was spilled _on_ the laptop, but rather next to it. This pattern looks like the laptop was in a puddle, and liquid climbed into the laptop through capillary action. A spill on the keyboard would've left the keyboard a sticky mess (which it wasn't) and the back of the logic board (facing up) was clean as a whistle.
That was a very educational and enjoyable repair! Your way of explaining is so relaxing and clear. I have a laptop here with liquid damage and hope I can repair it too. Never done a completely dead one with liquid damage so with me luck. (It's a very nice MSI 10th gen with a 3060 but no pressure for the repair thank G. so hopefully a very good learning experience). Thanks Graham!
Great content. It’s a great feeling when every thing goes as planned. I done my first screen replacement on a iPad 9 last week. What a relief when every thing worked after replacement.
Not sure when PLD added this, but you can also right click on "U8130" in the schematics, and that links to the board view location. As always: nice vid, keep it up!
I know they didn’t tell you about the liquid damage, but in all probability that was some time ago and they thought they’d got away with it. Or… Mum and Dad were away, the kids had a wild party and never told their parents they’d spilt JD and coke on their MacBook.
Yea, I think that was actually the case here, based on my conversation with the client afterwards. Someone had a spill and kept quiet about it because the laptop seemed fine.
Well done with the fix. I wonder was it the slightly tarnished ground pad that messed it up. It might of been useful to stick the original chip back in, after you cleaned up the pads, to make sure it was the chip at fault and not the slightly tarnished ground pad. Maybe it couldn't draw the right current before it was cleaned, which messed up the output and prevented it from starting. That might also explain why the diode readings were ok, dunno.
Yea, I also wish I'd checked that PGOOD signal that was 1.2v to see if it changed as well - sometimes you get tunnel vision while doing a repair onto a path that you know is probably going to work, and forget to test other stuff for research while you're there.
Sure would be nice if there was a charger for laptops that would charge the battery outside of the laptop. Being able to check the battery's health would be an obvious perk.
so many thanks for your lessons. Just fixed my first thing. A sound blasterx g6 headphone audiocard. Just changed a schotky diode with finger testing and measuring if it was working. Maybe it is just working because the new diode is not soldered right and it just passes it, i do not know why it works again but it does!!!
Really good video, Graham. Feels like the culmination over everything that's come before it on this channel. Since you see so much liquid damage in your repairs, I think it'd be informative to do a video on exactly how liquid destroys different parts of computers and electronics. Some things short out and others experience electrolytic corrosion when power is put to them. If you've got some donor parts to spare, it'd be interesting to see what happens when you purposely put liquid on various parts of them and start them up at expected voltages and currents. People generally know that water+electonics=bad, but we're clearly rarely told why. Especially about the corrosion part of things. As soon as someone spills something and their device _doesn't_ die, they start to think it's not such a big deal. And then maybe down the road it does fail, or the next device fails. Seeing how it actually works and how the detrimental effect could be there but simply delayed might get people to handle things more conscientiously. Might prevent some costly repairs even.
This is a great idea. I'm planning on re-doing the Board Repair Basics series, and this would make a good sequence to show what kind of damage you'll encounter and how to approach it.
Between the schematic PDF and a few other cheat sheets I have, it can be done without FlexBV. But would've taken much longer, and the longer it takes, the more chance you have of loosing heart and giving up. Also a shout out to the BST-050 super fine probes I use, those tiny resistors on the back of the CPU would've been a nightmare to measure with stock probes.
That centre pin of the removed chip looked dirty to me. I don't think ultrasonic works for thick liquid spills under chips, because most repair vids I've seen they pull the chip and clean under it and try again.
Where do you get your schematics and board views from? Everywhere I look there is always a catch to buy a load of programs that will be useless to me later.
You put a looooot of time into this board so I was wondering how much you would charge for something like this where you do the full package of service with cleaning included?
Does placing the motherboard in a zip lock bag with the deionized water and cleaner and filling the tank with regular water work as well as not? For the sake of keeping the tank clean.
I've heard a few people suggest this, seems like a good idea if you don't mind the extra steps of bagging and unbagging everything because ultrasonic fluid is expensive. So the bagging strat to save on cleaning fluid seems fair. Still use de-ionised water in the main tank though, just so you don't get scale and scum build up.
Hiya Graham, A good video pal and great to see how you are progressing in your repair videos :):):) I am still struggling in diagnosing the (not obvious) problems on my board repairs and always seem to get the opposite power rail problems with all the youtube videos I have seen, I struggle with what rail creates what and where to check next. I purchased FlexBV which is a great help but wonder if you can tell me where I can get those very handy notes you mentioned in the video?
Check this video by Paul Daniels that shows how to download the measurement and notes data for schematics in FlexBV: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-1n6A17ILurc.html
Also here's some extra resources relating to the issues I was working on in this video, showing power-on sequences, and PM_SLP_S4_L: logi.wiki/index.php/G3_to_S3_State_for_Ivy_Bridge_Haswell_and_Broadwell logi.wiki/index.php/User:Piernov#I_am_missing_SLP_S5.23.2FSLP_S4.23_.28PM_SLP_S5_L.2FPM_SLP_S4_L.29.2C_what_do.3F
@@Adamant_IT Good to hear - we want you to keep making these awesome videos! Overall, you have the most explicitly helpful computer repair content on RU-vid...and I know them all. Very appreciative of all the hard work you put into your videos. Keep it rolling my friend!
Good to know! I've been reducing my times down a lot, I'm not sure where I got the idea from, but I thought people ran them for waaay longer. Another factor is learning that some corrosion still on the board = "it couldn't remove this" not "it needed more time"
@@Adamant_IT Yea youve got the right idea! You have a great ultrasonic cleaner you definitely don't need more than 5 minutes. Excellent repair by the away!
Well done Graham. I would never touch apple equipment they are too weird. I will stick to windows platform for laptops and desktops so much easier. Although I do have an iphone and ipad. :)
Nope, it can open a variety of board files, big range of format support. The extra notes I had are mac only though, just because Mac boards are very well documented vs PC laptops. Theoretically repair notes for any board can be submitted to the database though.
Look I'm no where near the expert or the skill level you are at Graham but would it not be prudent to see if the fan actually works after being doused in Coca-Cola. Tiny bearings sticky gooey coke stuck fan? I mean to just rule it out at first. Love the skill you have,love the level of knowledge you possess. A great video.
If the fan turns by hand, it probably works, and this one did still spin freely. But also, at 14:16 I put the back of my hand against the CPU to check for heat, which would've been another sign of life. Worth pointing out next time though, yes!
Great video as always Graham. But I believe I noticed a dark pad on the right side when you first desoldered that chip. Could it be just the fact that fixed it? I mean you cleaned up all the pads and reapplied fresh solder to all of them. So could it be that the chip you removed and replaced is not faulty and it was bad contact because the cleaning did not manage well this exact area of contact?
I wonder if there exists any board views (like that with repair guide) for PC laptops. Please if someone knows please let me know. Greatings from Poland
yeaa.. i had a old stationary computer that i gave to my newphew.. later on it doesnt work anymore. Took it home and teare dit apart. Discover liquid damage on GPU. No wonder why ppl keep silent about it. Computer itself works but the GPU. Oh well.. told him afterward.. but his eyes looking other direction and like uhh i dunno.
Hello Adamant, one question if I may. If PMP_SLP_S4_L is About 0V, does it mean signal is present or missing? _L means that signal is present when voltage level is low.
Yea, _L means active low. In this case active means "we are in sleep mode, do not turn on." Reset signals are often Active Low as well, so 0v = "we are in reset, do nothing." and then when the signal goes High (inactive) that means "we are no longer in reset... do stuff."
42:05 That's normal after the battery has been disconnected, it basically just does a automatical NVRAM reset. I don't remember it being the case before though, maybe it's been part of some EFI update with newer macOS versions...
Agreed, I've only started noticing it showing up on newer machines, prior to 9 months ago it wasn't something that was common; caught me out a few times when it occured, making me think "Oh no, we've got more faults?"
A cleaning agent works better. Ultimately, alcohol will just evaporate off, even if you diluted it. And likely fill the room with vapor in the process!
Hmm seems my subscription got dropped, watched and liked loads of these vids. I have a question I have an Asus X401A laptop that had a keyboard fault then the motherboard failed (went click) I know I could probably look n repair it. I bought another secondhand motherboard and a replacement keyboard (plastic welded grrr). The problem is the motherboard turns out to be an Asus X501A yet fitted perfectly in my laptop, yet the new keyboard did exactly what the faulty one did. I inspected the back of the faulty one and it was full of crumbs and heaven knows the plastic protector on the back was full of crumbs and everything else, looked like some leakage under the plastic but couldn't see any damage on my original board (my laptop bought off Fleabay) Do I take it that the X401A and X501A are not swappable because the keyboard traces are different? Help. I loved the sizzle in the ultrasonic cleaner, you are right quit while you're ahead, as in teeth but you'd be stripping enamel away if you continue same principle.
If the connectors are the same on a keyboard, the pinout will almost certainly be the same. It sounds like a fault on the mobo side, which can happen. But also if it was a second hand keyboard, you might just have two faulty keyboards :(
@@Adamant_IT so I may have wasted 30 mins re-plastic welding, yes keyboard was second hand I'm an Idiot. Got some spare cash bought same X401A1 minus palm rest n keyboard, wasn't spare cash but will resolve an issue. There are ceramic filters above the keyboard connector haven't a clue how to test them to see if they're faulty. Got basic equipment voltmeter etc. Got no money left, this is a hobby learning curve. I appreciate you responding.
