Laptop Computer Repair.  - Page 1
Forum section: electronics / repair

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: October 06, 2019, 12:46:30 pm
content: Hello everyone i had my laptop going dead yesterday. Below is my post from Tom's hardware. I have decided to post it again here because of this forum's members experience with electronics.QuoteAs stated above thanks in advance. Extra info I was powering up an esp8266 with an external power supply while programming it from the laptop's USB port. The thing is that the Vin pin of the mcu is isolated from the USB port so I have nothing else to suspect but the sudden power losses.Thank you so much for your time.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: October 06, 2019, 01:18:09 pm
content: Btw here is the main board schematic

author: PKTKS
author_rank: Super Contributor
timestamp: October 06, 2019, 03:01:19 pm
content: Before you start weird things on the MOBO itselfCheck **IF** your PC will work fine using another PSUprefer a LAB PSU with controlled CC/CA to stress theMOBO with things... like .. say FURMARK and Uningine...If that works ... check your PSU with a proper LOADusing the rated maximum AMPs. Should pass the testor it just gone wild with the shortage.Paul

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: October 06, 2019, 09:30:53 pm
content: I don't have a proper bench supply to test the motherboard. The only thing available is a 18,5 V 3,5A (65W) laptop adapter and some cheap Chinese boost converter pcb's

author: PKTKS
author_rank: Super Contributor
timestamp: October 07, 2019, 10:06:59 am
content: Nop. This can make things even worstYou have one possible alternative of using a KNOWN GOOD PSU.I mean it. It must be good because if the original hassome sort of current weird fault you will not spot that easilyAlas.. the bench supply with proper CC/CA ConstantCurrent/Ampereslimitation is not expensive.. and mostly required to do any thing repair.Worth 1000 times any money on itself.Otherwise.. you will fallback to change this change that.. recap thistry that methods...Also valid but can be even more expensive..Some PSU faults can drop the voltage below threshold onsome faults when current reaches above certain valuecommon fault on that cheap external notebook PSUsdropping things adhocPaul

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: October 07, 2019, 11:30:14 am
content: Thanks for the answer I will send the laptop to a proper repair shop and invest in a bench power supply that I wanted for some time now.

author: PKTKS
author_rank: Super Contributor
timestamp: October 07, 2019, 04:51:58 pm
content: A last resource may be kindly ask to power your notewith some well good known PSU (even at the repair...)It may work normal enough to suspect the PSU was indeed damagedA last tip on Bench Power Units target to MOBOs is that:- mundane notebooks require a higher voltage with (comparable) lower current- on the other hand desktop MOBOs require smaller volts (12V) but insanelyhigher current - at present some GPUS+CPUs would require a quite expensivebench power supply capable of powering (controllable and measured) at leastand safely 30 AMPS. (12V @ 30A or 50A roughly 500W regulated bench unit)The last one is not cheap. But the notebook bench units are rather simpleand quite affordable.Paul

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: October 07, 2019, 05:42:01 pm
content: I told the technician to try powering the laptop from a known good power source to check the motherboards integrity. As for repairs I don't really do many but a good bench supply would be handy! Now that I am thinking about it the power supply was outputting 20v when the label said 18,5 v but I assumed it was due to the lack of load on the computer side.

author: geggi1
author_rank: Frequent Contributor
timestamp: May 18, 2022, 11:04:22 am
content: You have to start simple with the most likely cause for failure the PSU. Borrow a PSU from a friend.If you have tried with another PSU and the laptop is still dead and will not boot it most likely the BIOS.

author: rob77
author_rank: Super Contributor
timestamp: May 18, 2022, 01:38:08 pm
content: laptop is supposed to work between 3 cell lipo voltage and whatever the charger voltage is. don't place too much emphasis on the power supplyit has to be good for sure, but it's definitely not critical.check the voltages - go from charger input , check B+ rail - that's your combined rail supplying the whole laptop (either coming from charger sitting at around 19V or coming from battery and is much lower ). if B+ is not present check eround teh BQ circuit PU301 in the schematic. if B+ present then check the 3V LDO - it's in PU904 , this a is a voltage which powers the KBC (keyboard controller) which in turn is responsible to enable the always on rails - (signal EC_ON to PU904 and PU905) if it reacts to power on then check your always-on voltages +3VALW and +5VALW if those are present and it's not powering on then it might be some other supply rails are missing or shorted (check further by schematic) or you might be having a "rotten" bios.

author: Bicurico
author_rank: Super Contributor
timestamp: May 18, 2022, 04:33:37 pm
content: How about putting the battery back in?You probably drained the battery cell on the motherboard by now and that puts the laptop in an undefined state when power is cut off.Laptops were designed to have their battery inside. I don't understand why people insist on removing them. They will age with or without use and modern battery management will not charge the battery forever or let it drain.

author: ebastler
author_rank: Super Contributor
timestamp: May 19, 2022, 05:49:23 am
content: Gentlemen, this laptop probably does not exist anymore. This thread dates from 2019, and was just resurrected by new user "Barathrum", who most likely plans to add a spam link next. Reported.

author: Simon
author_rank: Unknown
timestamp: May 23, 2022, 02:10:09 pm
content: he did, banned!