Toshiba C55 No 3.3/5v rails [Fail] - LFC 

Graham, you have the patience of a saint. One of the reasons I never really got into board level repairs is that sometimes, you just can't find the source of the problem, even with really good equipment (although that helps). Sorry that a reasonably priced replacement board is not available to you as that would be the cost effective fix in this case. As others have previously said, It's really enjoyable watching you work even if ultimately there is no good solution to the problem. Cheers mate.

It amazes me how Adam hasn't any microscope and yet he manages to work with his bare eyes and a lamp mounted camera, this guy is awesome! Also thanks for fail videos, from our side it is so frustrating not knowing

I am glad you published this video.. it goes to show that repairs are not an easy street and not everything can be diagnosed. Keep the videos coming. Cheers.

Thank you from across the pond. I am learning an incredible amount watching your videos and much of it has been applied.

I was expecting the ITE chip to be bad and cause excessive current draw on the 3.3v rail, thus heating up your regulator IC.....but then again, you said you had no short on 3.3v.....strange one, but yeah - I too would eventually throw in the towel since you're wasting more time than it's worth. Great vid as always. Always looking forward to failed repairs since it displays everyday situations a tech might come across, me included.

Dude i cannot thank you enough for your channel....you have taught me so much and i cant thank you enough for everything you've done to my life!! Love your channel keep them up my dude luv ya like a brother xD

And yet it was one of the most interesting videos in electronic fault detection. Thank you very much!

The customer should be more than satisfied with your efforts, especially after seeing the vid. Sometimes the device is just a lost cause even if you are an electronics repair genius with top notch diagnostic equipment and repair tools. If your labour rates weren't as darn reasonable as they are it probably wouldn't be even worth investigating, other than at a superficial level to ensure there isn't a quick and easy fix. Of course it still makes excellent material for a LFC video so thanks for sharing!

The level of troubleshooting you do is nothing short of heroic. Do you know how many shops would've just told the customer that they need a new logic board and moved on with the replacement?

Keep the videos coming, even from the fails we learn! Admire your patience and for posting your fails as well!

The most probable thing is that trace connected to pin 2 of regulator (feedback if I remember well) is PCB internally shorted. You can prove this easily, testing for continuity pin 2 towards gnd, without the presence of the regulator. If there is continuity, you can try to isolate the pad under pin 2 with a cutter and connect through a wire feedback pin to the divider middle point. Hope this is clear...regards from Italy.

what a lucky find, i am a bit of an electronics hobbyist, your presentation is 10 /10, the image as clear and easy to follow, the verbal description of whats actually going on is very good. i book mark this page

when ever i come across a blown chip i simply just search the internet and look at close up of the motherboards image to get the numbers

Posting failures are rare these days. I appreciate this video upload as you are able to test your limits. hope there is a part 2. Watching this in Jun 2021

Put in your place, I would have arrived after reflecting; because I need a thermal camera (I see you already have one that you connect to the phone) and then also a support base for PCBs that I saw in panavise ... it's easy to say in hindsight but the decision would have been made right here, another way of To say it, this kind of motherboard problems has exhausted my patience. Thank you very much for sharing Graham and I mean that with absolute sincerity. All the best.

I remember from my my first commercial job after the airforce - back around '81 - we had a "Tone-ohm" in the workshop, to trace shortcircuited pcb tracks. Its a simple 4 wire milli-ohm tester with both a display and a beeper with a varying pitch according to the actual measured resistance. It had of course a range setting switch afair it had 4 selectable (milli) ohm ranges. It was easy to use and you quickly traced down a shortcircuited spot on a pcb.

Really enjoying your repair series. I actually repair guitar amplifiers. Many of which have partial SMD layouts as well as the discrete stuff and ICs. Very clear and helpful methods. Please keep up the good work. All the best from Sligo, Ireland

Very nice though, sometimes it just doesn't want to be found. And thank you for sharing this, it is nice to know, that it's not only me, who fails sometimes :D Anyway, keep up doing great job!

hat off to you graham. am laptop chiplevel repair student from ethiopia. i learn a lot from you. no one teach us in such depth. thanks keep posting up

This is like finding a serial killer detective stuff style.

Thank you for showing the torture, thank you for great technique

Its really tough to fix it You are great engineers and teaching it to all of the world , techniq connect to money and becoming rich but you want to teach your skill without fee, its great but sometimes you Should have to be commercial, its so hard to live without funds, thank you always for your Great lecture.

Please keep the FAILS coming, I think I like them more than the successes...Cheers.

👍👍 great investigation Graham! lots of teaching. If I was rich I would have sent you a flir camera! thanks for your sharing

1. USB short circuit is bad because it might lead to death of CPU or chipset. This? 2. Short circuit between layers under that regulator? 3. Some tiny capacitor or resistor somewhere on this line? 4. Gremlins? Good video! I'm waiting for a video about ALL of your tools. Especially poor man's microscope :) And you NEED a decent infrared camera.

Take laptop,add dynamite....fixed. Seriously,that thing is haunted. When I lived in the US ,getting a replacement MB was so easy I never got into board repair,that and my vision sucks. Great video,my friend.

Hi Graham, the schematic you are using seems to date to 2007 (see 20:49 of the video). That predates even USB 3, so there must be a later schematic for the C55.

These videos are really well explained

Even if you did'nt manage to fix it,still its entertaining to watch at the least and there's so much to learn

Keep on vlogging, I always watching your videos, and I learned from you little by little

Love all your videos and the way you explain things. You really give us a very clear way of how things work. I jus wonder why flux is not use when soldering and desoldering devices. Keep up your great work. I am learning a lot from you. Thank you very much for your time explaining thing!

I love watching your video's , they help me a lot, thank you

Fantastic! They just keep getting better. I leaned heaps on this video. Thanks Adamant IT.

You cannot win them all mate... Enjoyed watching this one just as much as the other videos...keep up the good work.

JP8102 looks melted into the PCB and dark on the edges at 10:12, I see under your tweezers, mentioned earlier where there was suppose to be "something" there but wasn't according to the schematic. Possibly remove the grounds on both USB Ports and not have USB (Isolation) may have (or may not if it's along the 5V Rail) been able to Power On. Great detective work sleuthing around by the way!

Great channel. The boards for that model are under $40 all day long on ebay. I usually just replace them.

You had it there. Just had to use thinner wires and trace it. Go for 2V and pump up the current as much as your power supply will give it to you but start with 1 amp and see how much and where the heat is. Then crank up the current if there is no noticeable heat. I had similar situation with one laptop which have dropped. I had interlayer connection on one spot. it was like weird resistance of 22ohms. My idea was to let the current thrue that part and see if the current will fall or will go up. Idea was to put enough current to burn that connection but not to high to weld tho layers together. I started with 1 amp and after a few minutes it fell to 0.9amp. then i pumped it back to 1 and so on. after halph an hour i was able to put enogh current there so burn that connection. the ressistance vent up to kiloohms and after i puged it up the voltage was restored to 12V. Unfortunataly i had one more circuit dead on that laptop so it is still not fixed, but i was able to sortthat short.

Hope you get too read this mate, you have the best tech channel on youtube and deserve many many more subs. have being binging your videos for a week now. cheers james

Thank you So much for returning an answer to my question. Have a Great Easter 🙂

Persistence is your middle name Graham. 😉😉 Thx for the detailed video!!! 👍👍

Enjoyable video, I agree with the idea that you probably learn more from stuff that doesn't go to plan.

Great, very informative video! You can learn a lot from failed repairs. Thanks, cheers!

very informative. just upload fail or fix video. your one of my favorite tech.

Back in the day I had similar problem. Drove me crazy. In my case I removed USB port itself and problem was gone. I assume there was something inside that port shorting stuff. In your case, its probably anyone guess.

Okay Okay, you've done your best and it doesn't work out, but then it's time to just put the thing aside. man that patience you have with this kind of work Yes of course you need that but still respect for your persistence

possible shorted inter-layer trace can be hard to find

Hi very nice video I learnt so much from you Is not failure videos video because Behind every failure. We have bigger success thanks 😊 👍👍

i watched only two videos from your channel i already learned Enough even though you failed this one

Don't feel too bad graham, we all get dead end faults and it's not because you think you are not good enough to find the problem. Yep i have also fell for the wrongly named continuity mode :-(

Ohhh another rabbit hole, those are the best! *fetches popcorn*

keep them coming very educational l love all your motherboard repair videos best videos

Regarding the hot air temp, a channel I watch, Paul Daniels (no, *not* the magician) uses an 8mm nozzle, 450°C at 110 litres/per minute. Your channel is very interesting. Thank you for posting the videos. 👍

I'm waiting for the 2nd part of this clip to see the solution..regards from Italy. 👋

@Graham, would be funny if you made a service sticker that said, "its fine now!" haha thanks for all the great vids from Australia.

hats off to your patience and dedication sir. advice: check boardview (.brd)file that will be helpful.

in the schematic the 1.8V Sense line from pin2 goes to a GMT_G2997F6U_MSOP10_10P chip, that itself controls voltages depending on power states, but it goes to a whole ton of other places. I don't think it's a sense line, more of a control line, because Pin2 seems to be T_ON

Well that was a fun ride to work, thanks.. Do a part 2 and Fix it . Come on man don't quit now.

Hi Graham. Dont give up maybe use a jumper wire and eleminat the inter line trace that caused the short

Very good video, not all motherboards can be fixed, but this is a great video anyways, thanks

you should look for pad 19 and pad 20 on the schematic, that could let you isolate and test the regulator output with no load on it. I think you need to trace the +V5A rail and see what it is feeding. Also, I did notice one of the small orange caps around the regulator you replaced looked cracked. Just left of the USB 0 ohm link. it looks two tone coloured. might be cracked/failed. worth checking. You did awesome troubleshooting steps though.

Watching listening to your Stream this past Saturday, I could not understand why the volume was so low on my C55-A (had the same problem last Mike's Unboxing Stream I was watching). Figured out the right speaker on the laptop has stopped working. Looking into cost of new speakers to see if worth the trouble of taking the bottom off.

Time to donate somethings to this guy, he's actually run out of a time working just with that multimeter

U remind me of my self have been fixing computer for 19 years started with fixing computers from the junkyard. 😎

Depending on the revision, the C55 motherboard is only $8.00 on eBay. Just replace it and add the old motherboard to your wall :)

Its really annoying that "engineers" took TWENTY years (1995-2015) until they standardized a USB connector that wasn't stupid. Yes, I'm aware that a dual sided connector is more expensive due to contacts at both ends, but they could have designed a connector like HDMI/DVI/VGA/etc. where its easily discernable which way it goes.

This is the very sad episode that I watch from you Adam..

still you did great and i learned a lot from this video :) thank you

@31:15 Btw, when you installed that controller chip, it spun 90° from how you originally installed it!

What I'd suggest is to test the voltage coming to that regulator, it looks like the bigger regulator is discoloured (top left) and if it is shorted and dumping 19v to the smaller regulator instead of reducing it to 5v, it could explain why the regulator is burning up.

"Don't call me Shirley."

low Impedance across the DC jack? Freudian slip perhaps?

That was a tough one. Great troubleshooting steps though !

Un video muy interesante ,muchas gracias ! Munudo trabajo de investigacion !

Good shout out for Louis. Think it was watching his site yours turned up as a suggestion.

Usually you don't need the whole schematic. In this case though, it is nice to have it. But you should know how to use it. That stand-by chip usually is at fault when it is hot. This time it was not. You certainly have a short on the 3.3V LDO side which feeds the RTC and a small part of the ECU. If you look in the schematic you can find that J... that you de-soldered and follow the line until you find the problem. The short on the feed-back line is your fault solely. You didn't assemble the chip correctly and made the short under the chip. That's why it disappeared when you removed the chip. When you have such a problem, remove the chip and make sure there are no shorts on LDOs first. Then reassemble the chip. Then look for enable pins for 3.3 and 5V rails. Then check to see if 3.3 and 5V are present. It was not the case here but this is the way to do it. Cheers!

One question for you @AdamantIT can you please tell us or show us which "poor man camera microscope" you use ? :) screen looks amazing but looks like you don't have some crazy big microscope camera for that. Thanks a lot if you answer me! Big fan !

I wonder if he ever got it fixed. I would have checked under whatever got burnt. I think the short is in the board. Btw I didn’t see a single bit of the video only heard it.

Hi, thanks for the video. When you put alcohol, the two transistors at the top left also seem to warm up

Thanks, you just saved my computer!

really enjoy the content buddy... get a thermal cam.. its a game changer and well worth the investment

Really enjoy watching the channel =D

Epic sticker collection on there.

Keep posting video!:) Fail or not. Im learning a lot. Thanks to you mate.

I'm not a elecronist yet, but if the 2A usb chip shorted out, for 1x usb2 1xusb3, wouldn't have made more sense that you repairing it should pick up a 2.5 amp just so it accomodates the user that fried it ? Or you think the smps was rated at a maximum and as such only 2 amps can be drawn from that dual port ?

Could the laptop have started when you isolated (by removing) the "solder blob bridge" near JP8109 ..? ( @45:00 ) ..? (I'm here because I know nothing) ... While I'd definitely like to know how [you] learned what you know and importantly, what that process consisted of! ... such as: Did you start off breaking things at 6 & tried soldering at 8..? Or did you get sidetracked from EE major? Or however you learned practical application -- as well as the principles (physics fundamentals) and, how deep your academic knowledge is. Can you explain from both a Maxwell's Laws as and then show how and why switching over to ThermoDynamics (conservation, etc) ..? Or is Ohm's law & hands on (kinesthetic) adequate..? Whether that's too personal or just not your 'cup of tea' ... I'd really get a lot out of videos drilling down on YOUR approach to: - The "normal" vs abnormal SMD component behavior (pathology). - How do you follow AC path, as traces LACK "observable continuity" ...? -- Does this require accurate expectations to be confirmation with a multimeter (DMM)..? - Given frequent relevance & apparent importance of "short to ground" & "shorts" or "ground" generally warrants a DEDICATED video! -- The meaning? When / where it's expected? How's it identified? And, "rote" repetition with a series of boards (practice.)!! - PLEASE dedicate a vid to the significance of continuity, impedance, or other DMM modes. - Many small components look identical; how do you tell them apart? Color? Memorization? Or just testing (DMM)? - Do you have "crutch" concepts for inductors, caps, diodes, filters, etc., that better abet _intuition_ than _tech definitions_ do? PLEASE do a video *Discussing How You Developed Schematic-Literacy!* I'd assume you'd need a relatively fluent understanding of the component on a schematics before reading one makes 'sense' ..? As reading comprehension depends on a vocabulary & concepts of nouns, verbs, adjectives etc are to understand sentences... While a vocabulary of words abets sentence comprehension, inference skills of a paragraph or page is another (higher) level. Understanding a circuit within a schematic "a phrase in this metaphor" wouldn't provide macro level concept of how it works together. YOUR VIDEO'S STYLE OF ... _hands on, practical application simultaneou to asides with technical explanations are utterly UNIQUE! And more importantly, WITHOUT PARALLELE ... and exactly what I was LOOKING FOR! Dedicating videos to each of the above topics would be, if not the only instance on youtube..? IMO, by far, they'd still be the best. This is by far the most useful and valuable channel on this topic I've ever found.

It seemed you had a lot of solder on the centre pad of the regulator

After you have cleaned the solder from the sides you should reflow it again with flux to eliminate any bridges from the center pad. More than likely that's your short to ground on the feedback

I love your videos man! Please keep it up :) God bless you.

Flux my man Flux good job keep em coming :)

Ebay or Ali Express, what a choice, nothing but quality.

I'm way way late watching this and forgive my ignorance sd well, but when you placed the chip on the board it spun, does that make a difference?

I think the short may be in the other USB section in the top of the MB and the jumper connection is made to have a overall the 3 or 4 USB feedback lines so it's actively regulated sorry for bad grammar

VCC doesn't have anything to do with constant current, it means collector voltage power rail. Conversely, VDD means drain voltage power rail. en.wikipedia.org/wiki/IC_power-supply_pin

Hello dears, I have a Dell Inspiron N5110 with no display problem. The main power LED is lit (on power key/and front LED) when plugged in or on Battery but nothing is displayed, CPU Fan is ON and heat is felt after a while as normally running laptop. I am posting this comment on this video because the problem occurred just after plugging a USB WIFI stick into one of the USB ports. I tried to output on an external display but that did not work. I watched few of your videos and I was really impressed with your way of explanation and analysis. I do not know your name yet, but can call you the Smart Guy. If you do not mind let us Fix this Dell as well. I disassembles the laptop, and examined visually any burnt components on the VGA/USB parts, but could not find any thing. What are your recommendations and guide lines to find the fault?

Power surge on the USB data line, goes straight to the SMC, blown SMC

You have to inject the 5 volts and the 3 volts coil so that you can find what is getting hot

If you left that Jump opened maybe the short doesn t get the regulator IC pin. So it could have right feedback and work fine. With 3V_ALW and 5v ALW present, you have a chance to get Power on.

Would a thermal image camera be able to help in these situations to find heat where there shouldn’t be or because everything is so tiny it would just look like one big heated mess lol, Just a thought ,FYI im a wood worker not an electrical engineer, just throwing my 2 cents in.

Looks like the voltage regulator spun 90° when you blew it with the hot air and it ended with the wrong pinout

to much solder in the middle of the pad. maybe the to much solder short the pins of the ic