That's how a simple fault can piss all over your electronics knowledge & experience 

Reverse polarity protection diode was doing its job and because the positive and GND were swapped, the diode was forward-biased whenever the adapter was connected, essentially shorting positive to GND. Unplug the connector and the "short" was suddenly gone, so the adapter restored its output. Measured the connector with the multimeter and there was no dead short, since you were only seeing a diode junction there. Good find - can drive you nuts !

The clue was @ 9:25 you measured +12V from the charger & @ 10:00 you measured -12v from the adapter, I enjoyed the video. Actually I watched it twice.

I feel grounded after this video.

I have never laughed this much on any other tech video.. I am dying..😆😆😆😆😆😆😆😆😆😆😆😆

You had it showing -12V several times and saying it had 12V while I was screaming at the screen and pointing at the minus sign. 🤣

My understanding is this: Their original adapter probably died and they replaced it with wrong polarity device. Input diode started melting due to wrong polarity, charger short circuit protection kicked in. Bios locked/corrupted due to Sorin's rapid and incomplete power off/on cycles using power supply.

Great work as usual... This is why its important for the shop to ask more questions, it would have saved time (and their cost)

Thanks for the video and lesson! Its often when there are two faults and you are looking for one that you get trolled.

I did think about a possible centre negative. It could be either the power supply or the adapter that’s been incorrectly replaced. Lovely to see a thumbnail from back in the day. 👊🏼

Great stuff. From past experience I learned to never assume anything and only trust what the customer says after you've verified it.

At 10:24 you have a voltage drop of -0.6 (diode) and I was convinced the input diode was reverse soldered because of the obvious meddling in that area 😅

I knew that cable was bad but resetting the bios would have stumped me. I do understand why you did though,...it was bound to be corrupt or frozen. Absolutely love you tackling all things electronic. Boundless learning ❤

Did you figure it out before me? :D

Nice to see when you work on a device other than a laptop. Wow, what a crazy fault! Never would think of that.😖 I would have called it a POS for a different reason.🤣 Outstanding troubleshooting.👍

Well done Sorin. I was ahead of you on that fault. I also wasted a lot of time fault finding a connector just like that one which was connecting video, and audio left & right channels to a video capture card. No video, and only one audio channel working. Same fault, The plug fitted better upside down than the proper way up.

I like all your video's Sorin. Thanks for sharing as always!

Very good, Positive ground, never would have thought it!

Hello🤝 I also had such a situation once in the First Austria console where the poles were changed plus and minus, good job👍👍👍👍👍👏👏👏👋👋👋👋

Brilliant fix Sorin, when you were messing with the adapter I guessed it was the fault, been caught out before like that thanks 😊

The plus is no ground😊😊😊

One of the first test I do for any repair, is to check the ground, and if it is positive or negative. It is an heritage from my first days, on hybrid devices (build with vacuum tubes AND transistors, usually all PNPs), This check would have identified the reversed power supply after a couple of minutes at most...

Good job hanging in there not quitting

25:46 best moment in every video ☺👍

in veata mea am vazut multe. da ca tine in prima oara, este ceva increDibil.🤣cred ca voi realiza un video.

I saw the thumbnail and thought you were going to be in the shop. I miss that old atmosphere in your videos.

Love it! I always wait for WEEE HAVE PICTURE!!!

Great video, mate. You assumed that the polarity of the connector was ok. But it was reversed. Assuming in electronics is never good.👍👍

Well done!

Great repair and repair man 👍

you are a genius

Good job mate 👍

Well, that was one the most stupid problems I had ever seen, imagine a simple reverse polarity due to a non-standard cable could take half an hour to figure it out! That's nuts. 😂

This was a really tricky one Soren.😊

Looks like a polarity converter/adapter - I had to buy one for a Casio Keyboard the other week as the centre pin was ground and the replacement charger I had to buy the centre pin was positive.

Good teacher😊

Thank you, sir, for an interesting video. 😊 Be a while since seen that issue Buyer beware kinda of thing.😅

Tough one Sorin. Great job.

good job bro love the videos

Indeed, lots of wasted time due to customers not telling all info. But thats always how it goes… As long as you charge per hour it doesnt really matter

Classic center negative confusion issue. You don't see these often. Great video Sorin!

That's crazy, well done.

Thanks for the video I watched it for a long time but I didn't understand anything and I was trying to understand but you go faster 🇹🇿 but I can say thanks and I still waiting for another

lol, nice one for a sunday. My day started amazing thanks to you Sorin. If it came to me i think i would like to change that charging port with a female socket which will fit that adapter so no one will confuse in future :D

😀😀😀😀😀 Congratulations from Portugal 🇵🇹

From now on, I will check ground and plus first. Thanks

i swear these types of puzzles should be preserved so other puzzle solvers enjoy them, it's so stupid it's funny but at the same time you just want to flip the table 😂

seen some of this symptoms from green corrosion of stranded copper wires inside ...seen some cases of green corrosion (sometimes pulvorized stranded copper wires in solar panel wires because of high current.....the reason sometimes I don't like stranded wires but it depends on where to use it.

I noticed something funny when you applied power and measured between the mosfet and ground and you got 0.60-ish volts. A diode drop. I thought someone replaced the protection diode backwards.

Your tweezer and wire testing cracked me up 😆Component at the power input is a Fuse not a Thermistor ? If the 12V power output is directly connected to the 12v power input then you'd had probably found the problem by simply applying 12v to the power output socket. Looks like someone has forced the power connector into the socket and damaged the socket thus allowing the connector to be connected incorrectly, I've seen this many times with those 4 pin style din connectors and even USB sockets.

haha one of those cases when we almost lose logic because of some of the assumptions that appear to be so obvious :) Thanks Sorin for this excellent video!

At 7.35 minutes I noticed the meter was showing NEGATIVE 0.6 Volts, as somebody else has stated, a protection diode is conducting due to reverse polarity of the psu.

You can see the dent in the adapter sleeve has to align with the slot on the inner plastic on the input but easy to miss because of the misleading slot on the metal outer sleeve on the input.

Lucky, never had a job like that, even if you can't fix they pay! Honestly surprises me every time.

I really thought it was the female PSU connector on the board that was defective. Maybe they didn't swap the adapter, but they did swap the charger/PSU. Some of them are inverted (plus outside the barrel, negative on the center pin). Nice one!

Swap positive and negative inside the ac adapter. Much better than plugging the connector upside down into the pc. And rub out the positive/negative designation on the ac adapter ....... and engrave new positive/negative orientation. That way it won't be doggy work plugging in cables upside down.

I knew from the second i saw a 4 pin proprietary power connector that the problem had to do with that. Ive similar things happen with uncommon connector, lik ones where there's a switch integrated into the connector so checking continuity when its not plugged leads to false conclusions or when extra pins require a pull up or down or interface somehow with input polarity protection. And ur lucky that connector was an adapter because usually its an uncommon connector u dont hav and u don't have access to the pins and u can't cut the cord to check cause it's the customers only one

OMG this is crazy, probably an hour or more for a reversed plug?!!! and with who? the master?!

Sorin, please, reduce the volume of the beep when you're working with the multimeter. It's too loud on phone speaker.

Something similar happened to me with a Dell charging connector with the white charging pin being grounded. 🤣🤣🤣🤣🤣🤣🤣🤣

What a fascinating problem.

POS have un conventional connection. the four pin connection looks exactly like Toshiba Qosmio X300 ac chargers , I know because I have one. the Voltage for the POs is 12v unlike the regular laptop is 19V.the reverse conection of the four pin adapter just to make it hard to use a regular 4pin charger beside of course the Voltage.

This is why it is important that customers tell repair shops everything.

13:53 I think this adaptercable is not the original part.

Minute 7:30, checking input voltage shows -0.56V! That's a negative voltage, and the leads on the multimeter are in the right order (red to plus, black to ground). This voltage can hint a protection reverse polarity diode FWD voltage drop, exactly on the input power jack... From that moment onwards, that was just entertainment... 😂

one of my favourite video

To me perhaps the power supply was wrong and should have been tip to ground ring to power, but plugging in the adapter the other way was a solution(and perhaps it was a tighter fit that way so won't fall out so easily? )

Excellent Saturday night comedy programme!

Some of this type psu connector also output 12v and 5v.

I’ve experience and at 16:82 I’m wondering what the flip is going on…OK at 19:41 I got it, it the wrong bloody polarity.. phew 0.5V one diode drop.That reworked component is a diode and it’s in backwards across the 12V rail.

Is making sense for voltage to drop if the wires ared skrewed and on load they drop connection ...

Electronic repairs by Ray Liotta. 😉

I was very confused about what "resetting the BIOS" could possibly mean. I think what that jumper actually does is "clear the CMOS memory", right?

спасибо ржу. причино следственные связи как что то потусторонние, с лицом загадкой

Hi Sorin, i don't figure it before like that... but sometime the swap positive exteranl & negative central PIN..... must look every time at PSU specifics.... good job i work few years for the GDO big distribution installing POS & Antitheaf and never happened me... Please replay to my ask on e-bay UK thank for the lesson bye Francesco Timpano from Florence Italy

"this is so simple. I don't get what's not to udnerstand" after 3 minutes "I am so confused" ahaha

24:23 a mirror under the screen will help

Thank you for give me good hope for all ❤️use What se have 🥰🥰🥰

U missed the minus sign 😅 but how did you fix the frozen bios?

Assumptions... As the punchline of the old joke goes: "If I were you, I wouldn't start from here".

I was wondering why you didn't connect your power supply to the short connector, could have helped point in the right direction.

What about the input connection?

This made me laugh. 🤣🤣🤣🤣🤣🤣

That is what we used to call a "Density Problem" in the shop. LOL Just make it an AC supply, then no problem !

🙃🙃🙃🙃Sorin das war verrückt du Meister der Elektronik

Oh Sorin - I was screaming at the screen from 1 minute in! Ive been repairing epos for 45 years lol there are 4 pins - 2 shorted pairs. on some the shorted pair run parallel to the flat side of the charge plug and others the shorted pair run perpendicular to it. I also know you have a customised version of the software - called ICR touch, if you look very closely in one of the top corners, theres a pink line as its been edited in paint - ergo I know that that terminal originated from the west midlands company based in West Bromwich and the guy that edited the blue background has now moved to Ireland. the 4th line down that you are covering with the paper is a phone number ending 5566? am i correct? If you need any help with parts or programming for that (i think its a titan 360 but there are several named models based on that chassis) AND SUNDAY IS SUPPOSED TO BE MY DAY OFF LOL

14:59 and you measure MINUS 12V.

Crazy !

That was confusing fault🙄😀

Can you please tell me the model number of this device ? It looks like a built in screen in a mini computer. I would like to get one of these. It has 2 serial ports on the motherboard and I need a computer with 2 serial ports Thank you

@ 10 mins you had minus 12v not plus 12v there are 2 versions of those adapters that have a different pin out where it plugs into the computer.

This is why I bought an Eload.

Doh, they replaced the PS with the barrel jack with a reverse polarity PS - lol -.

crazy adapter

so next time check the bios and flip cord upside down lol 🤣🤣🤣🤣

Hello, do you work in the UK?

That's crazy!

Yeah my father killed a HDD docking station 2 weeks ago with a 12v PSU with - on the inside and + on the outside of the plug….

+/-? LOL Done it myself. You don't look for a fault that shouldn't be there. WPIB (Wrong Part In Box).

I had a Dell charger , measures 19V , plug in .. no power & doesn't charge. Drove me crazy until I realized the male plug is bent.. straight = good but bent = dead. Cut open .. disconnected wires ! and I was checking the board !

😂😂😂 nasty charger