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.

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

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

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.

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?

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!

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

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

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

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

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!

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

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

These videos are really well explained

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

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

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

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

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.

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!

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

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

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

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

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!

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.

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

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.

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

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

This is like finding a serial killer detective stuff style.

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

That was a tough one. Great troubleshooting steps though !

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

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.

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

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

Really enjoy watching the channel =D

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.

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.

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

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

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

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. 👍

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.

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

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

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

Thanks, you just saved my computer!

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

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!

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

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

Nice info, thanks :)

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

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

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

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

excellent mate..

Epic sticker collection on there.

possible shorted inter-layer trace can be hard to find

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.

Thank you!

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

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 :-(

Good job and Thanks

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

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

Thanks for this video. Even if it's a fail.

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

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.

Good video

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

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

Good sir salute

Enjoyed the process anyways 😎

Thank you

Flux my man Flux good job keep em coming :)

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.

Changing de voltage regulator worked for me, but it was too good to be true. I was formatting the hard drive and after one hour, it suddenly shut down, no led indicators, totally dead. When I inspected the mobo again, it didn't have any short circuit but I could hear a very soft ticking sound that I could not know where it came from, checked electrolytic capacitors and they where ok. Any idea what to check?

The super io is powered from that regulator. It could be dead short and put the 3.3/5 V ALW line to GND.

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.

low Impedance across the DC jack? Freudian slip perhaps?

This is another classic highly interesting walk through... Great Work... irrespective on success. I think I would have cooked the friging board 5v 3A its the current that kills... At £10 for a like for like board might have been worth it. surely the Q11G NEEDS TO BE REPLACED as i guess its (USB chip) is linked to the feedback? couldn't see this from the schematic I would also ask the nice people from Toshiba : D

i see burning start up chip 😁 watching here from the philippines😅

short to ground check all capacitors in the ic outputs.

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

Thanks 😊

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.

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

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

"Don't call me Shirley."

i have a question about a graphics card i broke not to long ago i had a medal dropped on my graphics card while the computer was on and it felt behind the memory chips the card turns on but no video output could there be a way to fix that or if i want it repaired how much would it cost me. the card is a 1080 ti turbo

Thanks