Toshiba C55 No 3.3/5v rails [Fail] - LFC
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- Опубліковано 29 лип 2020
- I thought I was onto a really good fix with this laptop, but after a long slog I hit a dead end in all directions. Posting this because I feel like there's a lot to pick up along the way.
The last clue I had was; 3.3/5 volt reg heats up. Low resistance to ground (2.3ohm) on the feedback pin. The 'short' can be isolated from feedback, but the regulator still won't turn on while isolated, presumably because another monitoring chip elsewhere isn't seeing the isolated feedback.
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!
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
Keep the videos coming, even from the fails we learn! Admire your patience and for posting your fails as well!
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
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
Thank you from across the pond. I am learning an incredible amount watching your videos and much of it has been applied.
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.
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
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.
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.
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!
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?
Fantastic! They just keep getting better. I leaned heaps on this video. Thanks Adamant IT.
And yet it was one of the most interesting videos in electronic fault detection. Thank you very much!
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.
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.
👍👍 great investigation Graham! lots of teaching. If I was rich I would have sent you a flir camera! thanks for your sharing
This is like finding a serial killer detective stuff style.