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How To Repair Motherboard No Power

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Oct 22, 2010
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  • #1
I recently got a chore (one.5weeks in) as a 'laptop/component repair tech' in a minor shop and I'm in over my head. I've replaced/re-soldered AC/audio jacks before and can strip downwardly a laptop to diagnose components but not much beyond that (did one solder reflow in my oven). The tools they had there were an old school multimeter, solder, iron. I brought a desolder pump, capacitance meter, copper braid.

Final two machines (both Toshiba satellites weirdly) I got were like this:

No ability, no lights. Stripped downwardly didn't help. Adaptor OK, Ac jack OK, Fuses were all ok. Visual inspection gives me null (Burned northbridge or some such would be noticeable)

From in that location where practise I go? I guessed it needed a reflow since I didn't have whatever other brilliant ideas. I oasis't been able to find schematics for many boards either which would aid (I could check the power IC mayhap?).

If anyone here is familiar with this type of work I'd really appreciate talking yous for every bit much as you lot'll have me. I like the work and I am learning a lot merely I'm probably going to lose my job shortly, and I'm not sure what resources I tin can acquire from (other techs there can't fifty-fifty solder... had no idea what a de-solder pump was). If anyone has whatsoever vivid ideas about online resources I'd appreciate that too (troubleshooting laptops lead me here more frequently than not). Also wondering what cheap tools you might suggest I add together to my line... evidently non a rework/reflow station or anything.... I am just getting minimum wage and prefer eating to not :p

buzznut
Sep 26, 2007
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  • #2
Ok, here's the bargain-laptops are non made to be worked on. Desktops are pretty easy to work on and have few integrated parts, unless y'all're talking about budget models and dell, gateway, etc. Laptops on the other hand are highly integrated, and so if there's a failure its probable that the whole mobo needs replacement.

I would invest in a pc repair kit, they sell them on newegg for 20-40 bucks, depending on what you need and/or willing to invest. They are great, and typically take everything you will demand.

If a laptop is out of warranty, then the user is likely out of luck. At that place'southward a couple things to check equally yous surmised; the power cord/powerbrick, the adapter jack, and ability button. If all those things check out, information technology is likely a motherboard. Replacing motherboards in laptops is very expensive, at this point information technology is all-time to tell the client that you tin retrieve the hard bulldoze or the data itself but they need to get a new laptop.

Not expert news for anyone. However if it is still within warranty, manufacturers are pretty skillful about replacing motherboards. I had one die on my Compaq and they had it shipped back to me fairly quickly, and it was the motherboard as I surmised.

The reason for failure tin vary, but many laptops dice because of oestrus generated by the cpu or video chip. If a client needs to supercede a laptop, I would propose them to invest in a laptop cooler to avoid that issue in the future.

Y'all are going to waste material a corking deal of time trying to troubleshoot to the component level. Nobody does this, if yous can't supervene upon a switch or carte du jour to fix this, then in that location isn't much you can (or should) exercise. Once you have eliminated all possibilities, don't be afraid to say its a motherboard failure and motility on. Believe me, if y'all are only getting minimum wage for PC repair the folks paying you are not expecting much. Merely learn to troubleshoot things rapidly and everyone involved will be happy, people don't expect their PC to be in the shop for a calendar week or 2.

I recommend you selection up a simple computer repair volume and read up. Also web sites similar toms provide invaluable insight and communication. Practiced luck.

Oct 22, 2010
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xviii,510
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  • #three
I can diagnose most any pc bug down to the component level.... thats really easy.

And without a SMD or BGA rework station I likely cannot ready a ton of bug since northbridge problems are fairly common.

Things that are likely worth solving:

Bad capacitors. Decently mutual and the parts only cost a few cents.
Near of the ICs on board... 4-20 pin jobbies such as the power ic do fail and are swappable for less than a buck or so
Blown fuses. Easy to diagnose easy to replace. This is a definite.
Any and all damaged jacks. Power and audio being the about commonly broken.
Resistors. easy to find easy to replace. toll is in pennies
Transistors and diodes tin can be more than problematic to diagnose and set up but they likewise are cheap and swappable with merely a soldering fe.
Manifestly i can swap cpus and then I should be able to diagnose that as well.

I tin can't fix:
Northbridge or the vga bit without a BGA rework station so that is out of the question even if i accept to be able to diagnose it

I plant an example of the dude that does pretty much what is expected of me:

"Machine: HP G6000(aforementioned mainboard as V6000)
Trouble: not ability upwardly

The machine has been h2o damaged. It does not have arrangement standby power, which are 3V and 5V.

Check Max8724(the battery charging scrap) first, because to brand system has standby power this chip must piece of work correctly. This is a 28 pin chip, we only demand to examination 1, 2, 4, 8, 10, 11 pin. They are VIN(chief power for chip), LDO(provide 3.3V for scrap itself in order to set REF voltage, also provide point to bulldoze ii MOS to charge bombardment), REF(set reference voltage of the bit), SHDN#(enable/disable chip, a switch), ACIN(indicate the power supply has plugged in), ACOK#(power adaptor ok with mainboard).

Everything ok except x pin, ACIN is 0V. This is incorrect, mainboard doesn't detect there is an adaptor! Trace it backward and notice information technology is very uncomplicated – mainboard employ 2 resistors to pull the input voltage(19V, straight from dc socket) down to about 4V, and so exam the kickoff resistor and detect information technology opened. Change it and 3V/5V power come up and mainboard be able to switch on.

And so the trouble beginning when I try to charge the battery. The charging current never become beyond 0.15A and subsequently 10 seconds the charging low-cal start to flashing. Also can't switch on from battery. First, change Max8724, however aforementioned problem. Next check all the resistors effectually max8724 and change it if it has any sign of watering, notwithstanding no good. Then change KB3926(EC/KBC, chip monitors the statue of battery), nevertheless same. This is the mistake that I never dealt with earlier.

Decide to check MBDATA and MBCLCK, 2 signals that send battery information from battery to KB3926 before I give up. I find the MBDATA is short!

Finally, find there are 2 pins stick together on CN10(the connector of multimedia switch board). Fix information technology and information technology start to charging battery. Switch on with power adaptor, ok. Remove the ability adaptor in one case switch on, bombardment keep the mainboard running, ok. Only nevertheless can't switch on from bombardment once remove the ability adaptor. Think, call up, practise I miss something here or there? Oh, the CMOS battery non installed, put the CMOS battery back and everything piece of work perfectly. The battery part of troubleshooting takes me almost iii hours.

Call up, system may not run if you don't have CMOS bombardment or CMOS battery is depression for some AMD cpu mainboard.

I wrote this simply help people who involvement in repair mainboard have idea how to check the issues on mainboard."
Source: http://forums.whirlpool.net.au/archive/1223566

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How To Repair Motherboard No Power,

Source: https://forums.tomsguide.com/threads/laptop-motherboard-diagnosis-repair-no-power.263621/

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