Minis Forum HM80 Repair, No Power - LFC#370

hello interwebs welcome to let's fix computers I've got a mini a Mini's Forum desk Mini Mini PC here um which came in I think this one is no power I'm gonna double check my notes while I'm talking and well unboxing it rather uh where is it yeah that's right this is in for no power so we're gonna have a look at this guy and see if we can figure out why it doesn't well power on basically so um and there are a few caveats with this that we need to be wary of there's the power supply so this thing has a type c hmm no that's looks bad but it might be okay 65 Watts yeah that's doable yeah all right um so this has a type c power adapter but this is not uh the customer tells me that this is not a power delivery adapter and that kind of tallys with what we're seeing here is 19 volts 3.42 amps output doesn't list any other outputs if you look at the label of a proper USB power delivery adapter there'll be a whole list of outputs of all of the possible output combinations it can do so we've got to be careful with this because apparently this thing will just not communicate with a real power delivery adapter which I'll put to the test just for posterity and likewise despite the USBC you don't want to plug this thing into your phone because this thing will blow stuff up I had heard great things about minis Forum but I'm kind of disappointed to see this kind of thing this this this adapter shouldn't exist this is bad you shouldn't make this stuff because people are going to plug this into their phone going well it's the universal one it's the one that works on everything right no this will blow up your phone anyway ran out the way let's see if we can get this thing going uh nothing else of interest in the box so let's put all of this to one side and see if we can learn why this guy doesn't turn on roll the intro foreign so first of all let's just find out if this power adapter actually works or not so I'm going to hook this up we've got a green light on the power adapter you can just see our frame there now somewhere I've got a little breakout board that's a type c connected to a breakout board that would allow me to probe the pins on it however I'm going to try something else instead I've got with me Paul daniels's USB type-c power meter I'll just show you guys that on camera because I have not shown this thing off yet people who watch Paul Daniels this stream will be familiar with these guys it's his USB type-c power meter and this thing is really handy because it's got a USB interface to the computer so not only do I have a live readout on the display but also I've got this on screen readout that you guys are seeing as well so I'm going to unplug my type c power adapter from that and I'll plug in this guy here and we'll just see what happens all right so that adapter is knocking out 19 and a half volts I'm gonna see if it's doing that both directions yep seems to be no issue there okay then right I guess I'll plug this in and see what it does okay right so as soon as we plug that in the voltage tanks and you can see we've got pulses of current there that's a short circuit If Ever I saw one so there's presumably a dead short in this thing somewhere so let's get to opening this thing up so you can see we've got the pulses on the graph there really clear indicator of the power supply power cycling as it detects a short circuit and cuts in and out I had a suspicion that's what was going to happen which is why I hesitated but I was like uh I should take this apart and look first before I just blindly plug it in however also the customer has already tried to plug it in a dozen times if it was going to blow up any more than that it would have by now so for the sake of the video Let's Press On so I'll take the bottom screws out there and we'll just see what opens up that looks good right our power input is there we've got an SSD we've got some memory modules we've got our um bios battery there this is very similar to another Mini PC that I looked at recently which had a similar kind of case design to it just going to pull that back nothing exploded underneath there there's some big Looking Power planes here so we might be able to start probing that but I think what I'll do is I'll take the screws out and see if I can get the motherboard to lift out first let's grab this SSD and put it somewhere else this is basically a laptop on the inside tool intent and purpose let's zoom in a little bit as well too far hold it now the last one of these that I took apart it was a bit more complicated than just taking out these screws the top had to come off as well and it was all pretty horrible and it was all glued in I'm hoping this is going to be a bit easier to disassemble so let's gently have a look yeah that guy's coming up get the other side as well that'd just drop out if I give it a bit of a wiggle nope the top looks like it wants to come off if the top will come off then I will allow it there we go try that again uh-huh oh that's neat okay I want to disconnect those Wi-Fi antennas in that case I think I have an email in my inbox from Minnie's Forum saying hey do you want to look at some of our stuff foreign and I should probably get back to them because um I've Heard lots of good things about their stuff and they make some interest I like these little mini PCS I think they're very interesting and you know while I've criticized it for having a 19 volt hard-coded type c adapter um you know the rest of the design seems pretty neat okay I need to get this past there just a bit of there we go I just bent the frame outwards slightly and then it cleared all right so that's a neat design pretty simple heatsink there but they put a nice big fan on there they've put as big a fan as they could reasonably fit onto that which is good for uh which is good for noise I've just spotted that there okay let's start at the beginning so in the top left we've got a type c input port and it looks like we've got some typical DC in circuitry up there so let's dive under the microscope and take a closer look so this guy is going to be a fuse and that does not look like that's blown so I'm assuming that's our main input fuse so so in resistance mode I'll put my black Probe on this ground pad this screw hole on the left and let's just have a quick look at that guy I'm assuming that's going to be a ground oh no I lie we have resistance all right what about the other side of it yeah same there okay so um so that is going to be our 19 volts in and just for interest sake if I flip the board over again so we've kind of got a repeat of that on the other side you can see again we've got this big Center one and that all of those black dots are Vias which are um going through the board so it's connecting those big pads on both sides lots of stitching there so we have a very clear ground and 19 volts so they've just taken the the the hot pins from the Ute type c connector and just plumbed them all into um a 19 volt rail so this is where you would normally just have a DC Barrel Jack they just didn't want to put a DC Barrel Jack on there presumably because that doesn't look very modern but whatever so okay let's move a little bit further along then so we've come we've come out of our type c Port we've gone through a fuse into a mosfet so what about the other side of this mosfet it looks like we come out from there and we're going up um hold up a sec what are those are those capacitors yeah yeah in if we get the light right yeah those are capacitors they look kind of dark and naturally let me get a side on view there those don't look very good at all I wonder if those are our issue let's hold up let's count on taking measurements first ly is that is that even shorted so we come out we go through this DC in mosfet and on the other side we've got uh these three pins and these capacitors are we shorted yes so now we're shorted on the the output of the DC mosfet so my money is on these two guys just immediately um possibly this guy it all looks pretty sketchy uh where do we go from here then well again we've got lots of via stitching going through the board so let's flip the board over and see where it goes from there so once we've gone through the board there is another capacitor on the other side and then we're coming through here now is that an inductor yeah that's black so that is an inductor presumably in Rush and that is then bridging across to there is that our only inductor I'd expect more than one because this guy's got to carry up to 65 Watts but I don't know if it's a pretty beefy inductor then maybe so then we go let's see do we go anywhere else those look like more capacitors foreign yeah then two or two that looks like a current sense resistor difficult to see exactly where the trace is going here let's just peel that guy off and move him somewhere else let's try getting in closer so I can actually see the traces better let's just probe that out does this connect to this we might not be able to tell because if everything is shorted to ground then it'll be very difficult to determine and it's also very hard to hold this steady because I've got the fan on the other side no four kilo ohms there's there's stuff between there okay I assume we're still shorted to ground at this inductor so just put uh my black Probe on let's just find a screw hole that I can reach and check that inductor yeah we're still shorted I'm really tempted to take a pot shot at those capacitors just because they look really bad let's take another look at those see the top they look pretty darkened and when we get to the side and we go real close up that one on the left looks like it's fractured to me I kind of want to trace the circuit out further but also like we've got a Smoking Gun I might just go straight in on that and just try my luck sorry I'm doing it I'm just going to go straight onto those capacitors and just try my luck thank you so let's just stick some flux down over there to protect the pads and we're coming straight in with the hot air here we go I'm gonna try not to melt this type c connector but yeah um I'm gonna get the little guy as well for good measure yeah why not right we'll just give that some time to cool down now meanwhile I'm gonna have a closer look at this guy under here these ones on the back of the board look better so this guy's a little bit discolored but he doesn't look cracked or anything and this guy here cannot be our problem because this is before the mosfet where we're not shorted all right as our temperature come down now good enough for measurements you don't want to measure the board while it's baking hot because you can get misleading measurements the board flexes things expand and contract that kind of thing right Shot in the Dark and I don't believe it look at that I think I was bang on the money after a drought of rabbit holes I'm being rewarded with the easiest jobs in the world okay let's take a closer look at those let's take a closer look at those capacitors behold the transistor tester um if you do a search for transistor tester you'll come up with lots of little widgets similar to this guy that have some kind of screen and some kind of socket for poking through whole stuff into and some SMD pads for pressing SMD components against and what this guy does is you plug it in you you put your component in you press the button and it tells you what it is and what it's rated for very very handy tool to have in your kit for just identifying components they also function as a poor man's LCR meter as well so if you connect a capacitor up to it it will tell you the ESR of the capacitor because some capacitors will fail in a high ESR state where they are not short-circuited and they've got the capacitance but the ESR has skyrocketed which means they can no longer respond fast enough to be useful common on Old capacitors I think ESR failure is not something that I see very often in my line of work but it's a thing and proper LCR meters are surprisingly expensive so um let's stick one of these caps on it all right we've got a 10 microfarad capacitor seems to work and 10 microfarads is about what we'd expect we've got zero that looks like that one's a wire can we retest please yeah that's showing a resistor yeah that's dead short that capacitor so that's our dead guy so that's our dead guy and then finally we've got the little boy this might be too small to put on this tester oops and it just went flying shouldn't have bothered taking that one off that's fine that was probably um based on the size of that one that was probably a 100 Nano or something like that uh okay so the one that was dead and yeah the Dead one the one that is dead is the cracked one just as predicted so we need two 10 microfarad capacitors and a 10 nano now these are directly on the 19 volt rail so I've got to make sure that they're actually rated for um they need to be 50 volts and I don't think I've got any that are rated that high uh or 20 volts rather or 25 something like that so let me go and have a rummage and just see if I've got something that is rated High Enough all right I've got a couple of new capacitors ready to go we've got some uh we've got some 10 microfarad 25 volt capacitors here and I've got a 100 nanofarad 50 volt capacitor here to replace the one that I lost uh now this guy is kind of oversized but that's okay um it saves me from having to go and buy a tiny little capacitor and it'll do the job just fine uh how do I know that it's a hundred Nano you ask um I'll level with you it's a guess however um in cases like this this is usually um this is usually noise filtering um capacitance these are not bulk decoupling capacitors for a main power rail like this this is to reduce noise on the power rail it's part of ground Loop inductance it stops the ground plane of the circuit board from functioning as an antenna that transmits noise coming off of the lines as electromagnetic interference and most of the time you'll see something like 10 or 20 microfarad capacitors doing this job and there will usually be another smaller capacitor next to it that is typically an order of magnitude lower um so or two orders of magnitude lower in this case um most of the time when we look at that we'll see the same anyone who watched the MacBook Pro uh board video that I did very recently where I replaced capacitor on the right I O board we had a 10 microfarad and a 100 Nano farad so same deal there basically very very typical kind of values that you see there uh so let's attack this I am going to plug in uh my soldering iron and I'm just going to Reflow those paths a little bit because they're a little bit grotty and because I don't want to put too much power onto um because I don't want to put too much heat around that USB port I'm going to bother to Reflow the pads and get some leaded solder on those just so they are nice and clean and Reflow nice and quickly so let's turn this around so I've got nice easy access with the iron and just blob solder all over that we go now some flux and Wick there we go and now I might even be able to just solder in Iron hero this to be honest let's put on the 10 microfarad ones first because the 100 Nano I'm gonna do some modifications so shall we say I'm gonna scratch the PCB no I don't like that I think we're going to go for the hot air Reflow nah I don't quite have the clearance I need to get the soldering iron down there I could but not with enough Heats because we're on a ground plane and a power plane and before anyone goes garage cheers all out a chisel's not going to fit in there bro [Applause] a little Loop gonna quit while I'm ahead and now we'll just do a little bit of scrapey scrapey up here we're just going to elongate this pad a little bit thank you flux and solder there we go and grab my Hundred Nano farad needlessly chunky boy coming in and now we'll just stick some solder on the ends of those thank you ah I'll give that some more flux just so we can get some nice ends on those just my own peace of mind there we go we'll give it a micro pool of flux there we go there we go those are not the straightest capacitors in the world however I'm gonna quit while I'm ahead because if I damage that USB type c connector this job is going to get about a hundred times harder than it needs to be um sometimes it's you know like I could come in there with a hot air and more out and more flux and just Reflow those so they Nestle into place but again if I damage that type c connector now I've got to find a new type c connector for this and then fit that and just uh no I'm gonna quit while I'm ahead let's see how this guy looks right so I've got the customers 19 and a half volt type c adapter here it's going through my power meter so we're coming out on one of my cables plug that in and the computer is powering up all right and we should get some signal don't know if it's gonna oh there we go minis Forum aha so this should take us to a yeah there you go it's gone into bars because the SSD is unplugged but that is now a functional mini computer there we go um that's us done I'll uh quickly throw it back together again and we'll wrap up there we go and one more time for posterity HDMI and I'll plug the customers adapter just directly into the back now plug that in and we've got a blue light on the front and we should get a signal out from it in just a moment as well minis forum and that should start booting into Windows because the customer's SSD is in there huzzah that's a cool background oh no and that everyone is my heck in Ava media capture card going copy protected content God no anyway uh right thank you everyone for tuning in um that was a nice little fix that um I'm happy to get some easy ones because I've had a bit of a drought recently where all of the stuff that all of the board repair stuff has been things that are technically doable but outside of my skill range so having the easy peasy stuff that is very much in my skill range is a welcome relief uh thank you for watching everyone and I'll see you next time bye for now

Channel: Adamant IT

Views: 32,002

Keywords: adamant it, adamantit, computer, repair, shop, custom, gaming, modding

Id: MHKkhrUD2P8

Length: 30min 52sec (1852 seconds)

Published: Tue Sep 26 2023