Hp Laptop Screen Flickering repair - Test your knowledge - How a tricky fault looks like

[@silvake]

Ha ha! For the first 30 minutes of the video I was banging my head and screaming: IT"S NOT THE SCREEN. CHECK THE INPUT VOLTAGE!!! I encounterd this exact fault a couple years ago, on a Lenovo Yoga laptop with the same screen flickering, but only when running on battery. Back then I posted that case on your Discord too. That one proved to be a faulty battery, but the root cause was the same: input voltage not high enough on the inverter. Glad you figured it out in the end. La multi ani!

[@winlose3073]

but it worked when he bridged the main power rail again it means the voltage was good but why the voltage was pulsing? this is weird!!!

[@silvake]

@@winlose3073 in fact, not so weird. The pulses are not actually coming from the main power rail, they are rather a side-effect of that faulty resettable fuse, in this case acting as a current-limit device at the input of the inverter. The spikes are practically a result of the inverter load under insufficient current.

[@michaeldwamena9615]

I'm facing this same problem and I don't know what's wrong with my laptop

[@Amr_Dabour]

@@michaeldwamena9615 did u solve it ?

[@snitra.]

Greetings from North Africa, I had the same exact dim light issue on a Tinkelbel laptop, I was lucky to find the thermistor and replace it, it took me weeks t find the issue as I was working on other customers' devices , so one day I have made the doggy division to test the LCD backlight with a 30 PSU and it worked, then I started to suspect the input voltage of the inverter. Thanks for your hard work

[@abusidiksuleman3657]

I love it when I hear you exclaimed "we have picture", followed by a warm laughter ha ha haa😂😂😂😂❤😊 You are the best teacher that I have ever known when it comes to electronics. My legend 🙌 my hero, my mentor ❤ ❤❤.

[@ahmadayman529]

Sorin never fails to make me happy

[@atoms1978]

Sorin is rarely a good craftsman. It is pure beauty to watch you. Simple enjoyment.🇷🇸❤️🇷🇴

[@dimitristamatakis2431]

Hey Sorin, as much as I love the proper calibrated solution. Leaving the thermistor in place is that not why the screen dimming isn't working. As in bridging it with a wire is different from replacing it with a wire or god forbid another thermistor 😁

[@Aminanamous]

The teacher is back truly a legend

[@venerandarain3]

THE FIRST THERMISTOR THAT MAKE SERIOUS PROBLEM 😅😅, Glad to see you found the issue . have a good day Sorin .

[@alexn882]

This one was really interesting. I wouldn't have thought of checking with the oscilloscope when doing a laptop repair but that makes total sense. We do that all the time in audio equipment repairs since we have issues like this all the time. Really enjoyed this one, hahaha.

[@markkay8117]

100%, most repair technicians would also order another screen.

[@tkcomsiri7649]

Sorin You work really professionally.

[@TheTony111111]

Another entertaining video Sorin. Even after fixing many things over the years. like you. I still get a great satisfaction when i manage to fix something.

[@gurhanbayr5080]

Sorin this was a nice fault. Till you checked with a scope i was with the same mindset about the lcd as faulty. This was really a tricky one but a nice one. Nice catch and i think this fault cana be one of the top 10 interesting fualts in your repairs. Have fun regards

[@SONNYemc]

Imagine a Doctor says to his patient and states "the bad news is we took out one kidney, but you had two kidneys in parallel, so you're going to be fine, you don't have to replace it"😂

[@IAmThatGuy-ne6gw]

Not sure if you are being sarcastic or not. But that’s not hard to imagine a doctor saying that. I can imagine it being said everyday by one doctor or another. You can live with one kidney. My wife has been living with one kidney for years. And no one gets a kidney transplant until both kidneys are no longer viable. Because you will be fine with one kidney.

[@SONNYemc]

@@IAmThatGuy-ne6gw I thought it would never be said the way he said it Anyway, I sincerely apologise and I'm glad that your partner is well and healthy

[@zaprodk]

I find it confusing that you call these thermistors while they are polyfuses. They are similar in function to PTC thermistors in certain situations but operate on mechanical changes instead of charge carrier effects in semiconductors.

[@petermoore4056]

It seems that some of those smd fuses blow and leave a slightly conductive residue inside them, causing them to read a voltage on both sides.

[@peterlethbridge7859]

Learn't a lot on this. Very informative. Thanks Sorin.

[@levendlicht]

The first thing I thought was a kind of problem with a capacitor that integrates the PWM signal. If that capacitor would be faulty the PWM signal is not integrated to the proper DC voltage... This was a tricky one indeed... A thermistor (or polyfuse I think) never would have been my first guess. Good one Sorin!

[@LaptopDisassembly]

Usually in order the brightness to work, HP require Hot Key driver install also.

[@maklogetrich2378]

HP HotKey and HP Support Assistant

[@LaptopDisassembly]

@@maklogetrich2378 Support Assistant is more for automatic updates, and some personalization. I usually don't install it.

[@pacmanko4]

yes I think someone already reinstall the system and dont install all drivers with HP Hotkey and Support Assistant so maybe is problem there why brightness not dimming.

[@Swenser]

From the doctor's I get to see, you have much better reasoning and diagnosis skill. Doctors should aspire to be like u, not the other way around.

[@gajendragaja2870]

Supper I have same problem laptop after replacing screen same issue I need to check thermistor now thanks sorin❤

[@resqporter9137]

im currently faced up with the same problem. i had replaced the ower cables connected to the motherboard. still cudnt work. i changed the LCD screen, still cudnt work. i came here n found the solution. thank u so much I'm from south Africa

[@repairtech9320]

That information is gold. Thank you Sorin.

[@knightwar3]

This is one of your best screen repair and a very interesting fault nice job

[@carlospareja2579]

Excelent diagnostic Mr. Sorin.

[@Manhattanman52]

Absolutely fascinating video, big fella !!!

[@niczam461]

You trick us yesterday, you said you will put today a video of a HP laptop with ram issue :))). I am learning a lot from you. Thank you.

[@dontrotter1099]

makes my day when Sorin starts to laugh when he figures it out.

[@lovejoymakhaza5229]

i am learning a lot Sorin. now i have opened my repair shop

[@charon7320]

I dont care specifically about this vid, I just dropped to tell sorin, happy new year!

[@coolirc]

Nice job it's nice to see how the troubleshooting goes

[@blackdotkiller1]

Every day is a learning day 🤣 sorin 👍

[@victorchisenga9949]

That’s one of my favorite video .I like such jobs course they make you think outside the box and the satisfaction that come with it,it’s priceless

[@dexternengomasha7579]

Doctor Sorin. Am glad i have learned so much from you.

[@HectorLopez-jw2ke]

Hello I have the same fault but with a faulty charger. I use the oscilloscope to test de power rail if are extrange things.

[@di_luka]

Well done Dr. Sorin. 👏👏

[@AnonymousRepair]

Nice repair, some of the newer laptops gets the pwm and enable signal from the PCH and not from the EC anymore , had one that lines were shorted to ground

[@vasehristovski]

Hi Sorin that fault is same on tvs dark pic with flickering in that case i always put a load on the 12v to be sure that the thermo or fuse is ok

[@mahmoudsharafan2934]

Imagine if Sorin was a surgeon and they tell your family The Doctor removed your kidney because. No kidney no failing kidney

[@sub2001zero]

Oh boy!

[@ConradoFix]

Thanks for your knowledge, the information supported by your experience that you share is helpful.

[@aekdjdi4283]

Finally, we can start 2024 with a proper doggy repair. Doctor Sorin, your troubleshooting was proper outstanding, I was almost as happy as you when you figured out the issue...Really amazing!

[@davidlguerr]

You should always have 30 and 40 pin LED screens to test in those cases. Never trust others, always test yourself. And by having a screen to test, you avoid ordering not needed parts.

[@mcac-youtube]

yes, i think its mandatory have 30 and 40 pin Led screens to test before buy a new one. Time is precious and to jump the first doubt if is a screen fault or a motherboar fault is clever.

[@ДеянКънстракшън]

I agree with you but I think that screens are different not enough to have 1pc-30 pins and 1pc-40 pins.

[@maklogetrich2378]

@@ДеянКънстракшън just use a semi faulty screen

[@davidlguerr]

@@ДеянКънстракшънUsually it works fine for testing purposes.

[@fendularatsq2317]

good job, would have been nice to see signal again on osciloscope after you fixed it

[@peekpt]

It's not a thermistor, it's a POLYFUSE ! They normally open and heal after the short. The old one was shorted in that rail, the heal process fail.

[@mikanikolic1976]

now is POLYWIRE 😂

[@ziko2371]

That's I asked above,thermistor has values mych higher then 56ohns,1k and up

[@justicewasarirevu3412]

They are called polymeric positive temperature coefficient thermistors (PPTC). They operate like PTC thermistors in certain situations but they operate on mechanical changes and not charger carrier effects. In short they are a type of thermistors used as fuses.

[@electronicrepairservice2020]

Now that's some very impressive troubleshooting!!🤓 Another valuable lesson from experience.👍

[@ДеянКънстракшън]

Sorin, You are legend. I learn a lot of you.

[@john_Jean-Marc_JMP5184]

Hi Sorin, huge thanks for the video. Very interesting and always instructive to follow your analysis. Question for you, since a polyfuse is resettable, if i'm not mistaken, once the overcurrent condition is removed and the polyfuse has cooled down, it returns to its original state. In this case, would it be safer to replace it if it's faulty? If not faulty, should we find out why it wants to protect the screen, and maybe other components as well?

[@mihaiacer4395]

multumim ca existi nea sorin

[@RetroClaire]

You are truly the Bob Ross of electronics 🙂

[@oefzdegoeggl]

At around 18:30, i think what about checking it with an oscilloscope, to check whether maybe the 26V are actually a partial available 40V. let's see how it continues 🤔

[@oefzdegoeggl]

Amazing, almost there. So you checked the input, not the output. Good. Wouldn't have thought of the thermistor though, I had rather suspected a capacitor with dropped capacity w/o short.

[@Philippe-Philou]

Always in a good mood to see your videos😊, thank you Sorin 👍

[@Timpano_Francesco_Repairs]

Hi Sorin, very interesting this video i learn a lots... thank Sorin

[@naidol]

Best part is after ordering the new screen, Sorin cancels order 10min later 😂 brilliant 😂

[@Customer22374rt]

it was not going to hurt any if he kept it for himself for testing or keep it in his stock in case someone wants a screen replacement . I run a computer business and usually I keep parts in stock regardless if customer want it or not . stock is money, instead of customer wait days for a screen replacement or go to another shop to find one same day you can earn his business.easy money

[@tonylipford7310]

Check for PWM shorted to 3V on the LVDS cable. Replacing the LVDS cable is a tedious job, however it's really common for intermittent issues especially when it's run tight through a laptop hinge.

[@ShR33k]

Excellent video, but I am confused between 29:18 - 31:35 - how initially you had 10.9v, then something clicked... and obviously a lightbulb went off in your head and you knew what it was. But I'm confused when the second time you tried to measure the cap after the click how you concluded it was a thermistor when there was no reading on the cap second time?

[@dmisi1]

What a rare video !!! do you have revolut where we cand send "thank you"

[@steam-tech-retro-garaz]

Hi Sorin, thanks for all your interesting videos! Inspired by your work, for fun reasons - I now try to fix mine prehistoric Thinkpad T20 which died many years ago on the infamous BOD symptom (Blink of death). So far without luck. This was a common failure of the historic Thinkpads "T" and "A" series, I wonder if you ever had to fix this kind of problem? Maybe you could share your experience, if you still remember? Thank you and good luck!

[@computersrepaircotesaint-l7407]

Shocking video, very tricky faulet. The best tech

[@Iceking007]

So I'm wondering what that voltage rail is, what the thermistor is doing, and why you have a pwm signal on the other side. More classroom and theory would be nice here; I'm not certain I could fix this fault in the future, even given this demonstration. I need to learn more. Thank you.

[@jpius1017]

Try to update diplay driver brithness will be ok

[@jarnovilen5259]

Yes, the cables do break. I have replaced some that were damaged. Successfully repairing the problem caused by that.

[@silver60618]

How do you know if its a fuse or polyfuse?

[@pouletfritesmayo]

Happy new year Sorin ! hope you have lot of easy jobs ))

[@Gurmeetyadav1]

🎉🎉We have picture....I can't believe 😅....Love U from 🇮🇳🇮🇳

[@Dohcoms]

Excellent work!, i dont think i would have ever got that thermistor,lol

[@midgoog2]

Sorin, If you suspect a screen issue surely plugging in a HDMI screen would quickly see if your on the right path or not. Eric

[@WayneSallee-comTech]

A lot of cheap laptops don't even have a HDMI connection, but if it did have one, the HDMI screen would probably have shown a picture.

[@CRILIKk]

That’s awesome , thanks for sharing

[@somewaresim]

Could you have diagnosed with multimeter in AC mode?

[@WayneSallee-comTech]

Yes, putting the meter in AC mode would have shown the problem.

[@Mecano.r]

😂 Imagine if Sorin was a doctor, he will be like: lets short the brain of the patient, anyways he doesn't need to think nowadays 😂 Like always, we enjoy your videos 😊❤

[@huseyinkoc1452]

It was an excellent experience for everyone.

[@thedarkfuture01101]

This was a long one but I'm glad i watched all of it :D

[@rfr653]

Good job mate 👍

[@xx3868]

You could take the 26V and boost it up to 30V with a little circuit? or can you touch solder the chips and try to shot gun it?

[@younessamr6802]

the wire saved the day again

[@rachidoublal6877]

when you first said flickering, i immediately thought about you using the oscillometer

[@anuyahvictor9772]

That's crazy 😧 after all the stress just a fused!

[@larrygenedavis]

I am just wondering if you prefer using your handheld oscilloscope to one you plug in when working on laptops ?

[@WayneSallee-comTech]

I think he was just keeping his cost down by purchasing that oscilloscope, rather than a nicer desk unit, since he does not figure on needing it much.

[@elkanayunana2182]

Tricky job with a picture 😂... The great Sorin❤

[@winlose3073]

great repair! but if the main power rail is pulsing, does it mean that there is another issue with this laptop and could it mean that this issue kind of disappearing because of the input caps at each power supply?!

[@loverboykimi]

Unique!

[@bossmanfox3507]

This one was different. What was your thoughts that caused you to go back an inject 11v on the power rail

[@GregM]

I am a bit confused but it being Monday that can be the cause. Weren't inverters used on LCD displays that used cold cathode lamps in the LCD for backlights? The inverter I think were to convert the DC in the laptop to AC for the cold cathode display tubes. Newer LCDs that use LEDs for backlights do not use inverters. Is that correct or have i mixed something up?

[@neovita3818]

The proper calibrated fuse might be choosen a bit to low for the ~260 mA there

[@WayneSallee-comTech]

It's a laptop warmer. :-)

[@neovita3818]

@@WayneSallee-comTech :D you just made my evening with your answer, thanks for that =)

[@TTTupload]

Sorin maybe ordering chip was a good idea. Thermistor and chip can be faulty at the same time.

[@afb9999]

18 minutes in and I was thinking lid sensor. Also the brightness won't work with default windows 10 drivers only after windows update the driver

[@ashraffrancis]

Very nice fix

[@ElectronicsUDR]

yes, a new video! now i can start the day better

[@rahulmechatronics]

fantastic job

[@MrReeceyburger123]

Nice haha, I always take the base off and disconnect battery, plus unhinging the screen first before prying apart deffo can save time 😝 Also missing resistor and cap on the lcd pcb ?😊

[@gudurudeshwanth7076]

brightness problem is due to windows is installed freshly and the grafic driver was not installed just ubdate the windows sorin i hope it will fix it

[@Naushadkhan78623]

You are a MASTER

[@mayuramunasinghe1983]

Wow that was amazing .........!

[@lucataszarek8782]

Hello🤝you are genius 👍👍👍👍👏👏👏👏👏👋👋👋👋👋👋🤗✌

[@BP-sf7br]

@6.16 "a small incision here.... Well surgeons often say that😅😅

[@sachatack]

You are Santa Claus after christmas ho ho ho legend you are the best.

[@ziko2371]

Is it thermistor, ntc? Because I see thermistor in various values 1k and up

[@cjdelossantos5832]

Nice. I hope you also have a solution for Dell XPS half screen freezing (Sharp touchscreen LCD LQ133D1JX31). Most 13'' XPS from 9360-7390 models have this issue.

[@jalalyn]

I love what you do❤

[@dzoks-e7n]

Nice video,thanks

[@brucewalker1908]

Sorin. I don’t understand the thermistor. 50 ohms means it bad?? A good thermistor should show 0.00 ohms. Is that what I’m understanding.

[@justicewasarirevu3412]

That one is a special type of fuse. It works like a thermistors in some situations but is tested like a fuse hence very low resistance means the fuse is good.

[@47noeZ]

💯 intuition top teacher ❤