Identifying the Real Problem (DC Jack)

[DanF]

Will definitely try some of this tape. Should also be useful to replace removed tape in laptops then. Always wondered what's the name!

Are you sure this doesn't melt with a hot air gun? hehe

 

[jbartlett323]

Are you sure this doesn't melt with a hot air gun? hehe

Oh, I'm sure it does!!!!
But like I said, it takes some heat before it melts. In my experience if your melting your tape, your board is too hot anyway, so back off a minute! I've really only melted it after I had the jack out, and was immediately trying to do some clean-up. trying to keep the solder liquid while sucking it off can sometimes take a minute and therefore the heat builds up...

 

[DanF]

Thanks

 

[PCX]

A couple of suggestions:

For cleaning your tips use this.

http://www.amazon.com/Hakko-599B-02-Solder-Cleaning-Holder/dp/B00FZPGDLA/ref=sr_1_2?ie=UTF8&qid=1421692793&sr=8-2&keywords=solder tip cleaner

A desoldering gun also makes the job much easier. We use this.

http://www.amazon.com/gp/product/B009Q5ZH58/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1

And along with Kapton tape, we will use a heat resistant aluminum tape to seal the edges. If you are using a hot air gun or hot air rework station, this will keep the edges from blowing up and allowing the heat to get underneath the tape.

http://www.amazon.com/3M-Foil-Tape-3381-Silver/dp/B00A7I5L86/ref=sr_1_3?ie=UTF8&qid=1421692922&sr=8-3&keywords=heat resistant tape

Again, that is used just to seal the edges. You only need a small piece.

Of course as others have mentioned, bigger tips help, just make sure they are appropriate for the shop. The ones that comes with the soldering irons are usually way too small, although they can be good for really tight spaces. A small chisel type tip is better for small things like phones and tablets and a bigger chisel tip is better for laptop power jacks and other projects of similar size. Also, no clean flux is your friend.

Finally, keep your tip tinned and clean and don't forget to turn off your iron when not in use. It will burn up the tip and the heating element.

Other than that, there are some great tutorials on soldering, one of the best ones I found was a really old one from the 80s. Be careful though, there are a lot of bad ones too.

 

[Dee]

Yeah, that's a good tip. I'm working on an ASUS BU400A with what was reportedly a DC jack problem, and had to bend the two pins that contact the plug inner metal sleeve outward. Stupid jack on that model has another set of prongs that contact the outer sleeve of the plug and they will get stuck in recesses of the jack body if you happen to push them outward too much (see here). I just finished adjusting such a jack only to find the laptop will still not show any sign of life in spite of good jack solder joints and having 19v on those leads. Apparently it was a DC jack and a MB problem. The laptop is reportedly still under a 3-yr warranty and they had me fix it rather than wait two weeks for WorstBuy repair it. I guess all I'll get out of it is a diagnostic fee.

For future ref, these days if its not any obvious signs of the dc jack itself, its more common that it is a motherboard issue, for a quick check, i have a bench power supply that shows me voltage as well as amps, as soon as ive connected the power leads to a motherboard, i can see if theres actrually current getting through before ive pressed the power button, this helps to determin that the dc jack is faulty or not, if theres current getting through but not switching on, then you know its a mobo problem even before you get into heavy investigating opening up the whole thing. In this case commonly it is the bios chip that has corrupted which is attached normally to a kbc or ite sio controller which is in charge of power up, you would need to manually remove bios chip and program this externally using a chip usb programmer that you can buy from ebay. Hope this helps.

 

[Larry Sabo]

@Dee: Monitoring supply current is a good method. Unfortunately, I don't have a bench power supply with an appropriate range --never had enough reason to buy one, given their exhorbitent price. Which one do you have, out of interest. Re. re-programming the BIOS, I use a SOIC 8 clip, which makes it uneccesary to unsolder the BIOS, provided it can get a sufficiently good grip on the IC legs.

 

[Dee]

@Dee: Monitoring supply current is a good method. Unfortunately, I don't have a bench power supply with an appropriate range --never had enough reason to buy one, given their exhorbitent price. Which one do you have, out of interest. Re. re-programming the BIOS, I use a SOIC 8 clip, which makes it uneccesary to unsolder the BIOS, provided it can get a sufficiently good grip on the IC legs.

Any bench supply will do just to monitor current, not necessarily use it for complete booting, if you repairing laptops a lot, then you need to have the right gear to make you life easier and faster, within 5 secs if plugin in my bench psu i can tell if its dc socket or ,mobo, i can see that you spent a bit of time doing the things you done, could of saved you a lot of time, so its a defo bit of gear to have in your workshop, i got this one from ebay http://www.ebay.co.uk/itm/Adjustabl...989?pt=LH_DefaultDomain_3&hash=item3385adc8ed
simple and cheap but does the job, but be careful as I only use it to monitor dc jack problems and not really use it for booting machines as this one cannot supply enough current to some motherboards and so the laptops turns off making me believe I had another issue with the motherboard when it wasn't the case, took me a while to figure this one out.
Now for the bios clip, forget it, throw it away, useless thing for laptop motherboards, couldn't get it to reprogram chip properly, after heavy research, found out its because its connected in circuit, it will not allow you to reprogram the bios properly, you need the chip pins to be free and separate from anything, spent hours trying to get this to work, worked all right using it when chip removed it works, but wont work if chip is connected to mobo, im saving you time here in long run. This gadget is for hobbies't with some other type of circuitry, not good for laptop mobos.
Get your self a bench psu, you'll thank me for it, save hours trying to figure something out that can be done in few secs.
Dont get me wrong, if you got current going in and its not the jack may even be other stuff on the mobo and not bios thats bad like a power rail 3.3v or 5v alw, but thats another story, but commonly specially in HP's its bios corruption. once this is done and still not booting, then you start following schematics for power up signals on the board.

 

[Larry Sabo]

i got this one from ebay http://www.ebay.co.uk/itm/Adjustabl...989?pt=LH_DefaultDomain_3&hash=item3385adc8ed

Thanks. I have a 0-70v, 0-1A regulated PSU I occasionally use, but might look for one that can handle the MB load, now that they have come down in price. They used to be $300-$500 CAD.

There's a blog at http://www.laptoptrainingcourses.com/tech-blog, IIRC, where the author has a lot of experience with and also advocates for using a PSU for MB diagnosis, but I'd rather just get right in there with a DVM and schematic myself. Subscription to that site was just $70 or so when I subscribed, and came with a truckload of schematics that have been very helpful. A lot of the material provided is elementary and a bit of a dog's breakfast/disorganized, but some of it is still worth a read for the diagnostic tips.

Now for the bios clip, forget it, throw it away, useless thing for laptop motherboards, ... This gadget is for hobbies't with some other type of circuitry, not good for laptop mobos.

Yeah, it sometimes won't read the BIOS, but it's not as useless as you suggest, at least in my experience. I just take multiple readings -- if I can get any at all -- and verify that the check-sum is the same for each reading before counting it as a good read. Even with the BIOS removed, the clip sometimes fails to make good contact and the chip needs to be soldered to an adapter board before it'll read. Sometimes, unsoldering/disconnecting the CMOS battery helps, sometimes not. The clip is still handy for reading/writing hard drive ROMs, for transferring adaptives to a new PCB, provided no 1.8v chips are on the bus.

Get your self a bench psu, you'll thank me for it, save hours trying to figure something out that can be done in few secs. Dont get me wrong, if you got current going in and its not the jack may even be other stuff on the mobo and not bios thats bad like a power rail 3.3v or 5v alw, but thats another story, but commonly specially in HP's its bios corruption. once this is done and still not booting, then you start following schematics for power up signals on the board.

I agreed about the usefulness of external programmers for re-flashing the BIOS, and that corrupted BIOSes are a common cause of non-POSTing. Can't live without one if you're repairing MBs. While I find discussing detailed MB diagnosis/repairs interesting, it perhaps belongs on a MB repair forum rather than here, where few of the readers are electronics techs.

 

[Dee]

Thanks. I have a 0-70v, 0-1A regulated PSU I occasionally use, but might look for one that can handle the MB load, now that they have come down in price. They used to be $300-$500 CAD.

There's a blog at http://www.laptoptrainingcourses.com/tech-blog, IIRC, where the author has a lot of experience with and also advocates for using a PSU for MB diagnosis, but I'd rather just get right in there with a DVM and schematic myself. Subscription to that site was just $70 or so when I subscribed, and came with a truckload of schematics that have been very helpful. A lot of the material provided is elementary and a bit of a dog's breakfast/disorganized, but some of it is still worth a read for the diagnostic tips.

Yeah, it sometimes won't read the BIOS, but it's not as useless as you suggest, at least in my experience. I just take multiple readings -- if I can get any at all -- and verify that the check-sum is the same for each reading before counting it as a good read. Even with the BIOS removed, the clip sometimes fails to make good contact and the chip needs to be soldered to an adapter board before it'll read. Sometimes, unsoldering/disconnecting the CMOS battery helps, sometimes not. The clip is still handy for reading/writing hard drive ROMs, for transferring adaptives to a new PCB, provided no 1.8v chips are on the bus.

I agreed about the usefulness of external programmers for re-flashing the BIOS, and that corrupted BIOSes are a common cause of non-POSTing. Can't live without one if you're repairing MBs. While I find discussing detailed MB diagnosis/repairs interesting, it perhaps belongs on a MB repair forum rather than here, where few of the readers are electronics techs.

yes you are right, im new here, but i do find that all things laptop are related and connected and its difficult to be able to draw a line where an issue comes up and techs are looking in the wrong place, for me anyway, if you going to repair stuff, you do need to know the ins and outs, looking at the small picture only gets you confused, need to know all. I get most costumers in my workshop coming to me and telling me that i just need new windows installed or I need a new dc socket or i need virus removal or its "Just a loose connection inside and should be a easy fix" when they should be telling me what the problem is that there experiencing, they are not techs!! Most of the time the problems are more then what they think it is, and so when a discussion of dc jack problem arises and i can see it is motherboard related, its hard to not say anything, im sure i will find other forums where it may seem im replying in the wrong place, but this level of repair aint so clear cut in sections, i do apologies again, ive had a lot of experiences which im willing to share, as many others.

 

[NYJimbo]

i have a bench power supply that shows me voltage as well as amps, as soon as ive connected the power leads to a motherboard, i can see if theres actrually current getting through before ive pressed the power button, this helps to determin that the dc jack is faulty or not, if theres current getting through but not switching on, then you know its a mobo problem even before you get into heavy investigating opening up the whole thing..

But to connect power to the motherboard you would have to get access to the mobo at the point of designed entry, at or around the Dc jack. Since most laptops are designed so you cannot get to the mobo at that point without tearing them down, I don't understand what you mean by "heavy investigating opening up the whole thing". You can't just pick an arbitrary point to introduce power.

Just not understanding your method of doing a hardware diag on a laptop.

 

[NYJimbo]

Dont get me wrong, if you got current going in and its not the jack may even be other stuff on the mobo and not bios thats bad like a power rail 3.3v or 5v alw, but thats another story, but commonly specially in HP's its bios corruption. once this is done and still not booting, then you start following schematics for power up signals on the board.

Commonly in HP's is not the BIOS but a BGA chip that's gone bad. Do you really assume its the BIOS ? Do you desolder, reprogram and resolder all BIOS chips if the machine shows current flow but not boot ? If this is your method for HP's what about UEFI BIOS ? What about non-HP, what do you do ?

btw - can you share with us where you get your schematics ? Its very rare to find any for newer models.

 

[Larry Sabo]

But to connect power to the motherboard you would have to get access to the mobo at the point of designed entry, at or around the Dc jack.

Hi Jimbo,

Not speaking for Dee, but I assumed he cannibalized a lead from a universal adapter and used the appropriate plug with it.

Edit:
Not what you were asking about Jimbo, but for others just getting into MB repair: (Redacted: link to a Torrent site that contains the Laptop Repair Training College course and schematics, because of copyright.) There is also an old video on repairing laptop power circuit problems on sieguntur's YouTube channel that provides a good introduction, using a DV2000 MB and schematic for reference.

Edit 2:
From the waybackmachine.org, here's the original Laptop Repair Training College Tech Blog that reviews many MB repair cases. The original tech blog was available to all, without the need to purchase the course, so I have no qualms about posting the link. In the blog, the author talks about using a bench supply as a diagnostic tool.

 

[Dee]

Hi Jimbo,

Not speaking for Dee, but I assumed he cannibalized a lead from a universal adapter and used the appropriate plug with it.

Edit:
Not what you were asking about Jimbo, but for others just getting into MB repair: (Redacted: link to a Torrent site that contains the course and schematics, because of copyright.) There is also an old video on repairing laptop power circuit problems on sieguntur's YouTube channel that provides a good introduction, using a DV2000 MB and schematic for reference.

Edit 2:
From the waybackmachine.org, here's the original Laptop Repair Training College Tech Blog that reviews many MB repair cases. The original tech blog was available to all, without the need to purchase the course, so I have no qualms about posting the link. In the blog, the author talks about using a bench supply as a diagnostic tool.

Spot on Larry on all counts, I have used an old adapter dc lead, on the end and i am using different adapters to fit mobos. ( how do you do a like in here?)

 

[Dee]

Commonly in HP's is not the BIOS but a BGA chip that's gone bad. Do you really assume its the BIOS ? Do you desolder, reprogram and resolder all BIOS chips if the machine shows current flow but not boot ? If this is your method for HP's what about UEFI BIOS ? What about non-HP, what do you do ?

btw - can you share with us where you get your schematics ? Its very rare to find any for newer models.

Yes i do bios chips as I have a oscilloscope to look at wave forms, another way to know about bios is ok or not is to check RSMRST singal, as Larry has noted, this is wrong forum for this level of repair so i do apologise but just trying to answer as breif as possible. Yes i do re-balling bga although I like to put in new bga chips in for extra measure of last ability, and yes also bga is a common fault not just in hp, but in any amd chipset motherboard as in my experience, amd seem to heat up very quickly over time then intel, most motherboards in my workshop are amd related if bga fault, however, this has nothing to do with no power getting into board. From my bench supply, as Larry has figured out, i have a multi adaptive end to fit any motherboard dc socket, I just plug it in and see if im getting current through from reading my PSU current display, if i see current getting in, then i know problem commonly on the board, if not, then socket is faulty, this just prepares me within few secs to tell costumer that it may well be a mobo issue and i would have to open it up to investigate, in this case it could be a lot of things but commonly bios or power circuit problems. Bga fault however will not stop current going into motherboard as you would see on the PSU meter reading display and also most of the time you will see some signs of life of power led or fans spin up and switch off. sorry lary if i waffled on a bit on this subject.

 

[Larry Sabo]

Dee, to answer your question, the Like button is at the bottom right of the post you are thinking of Likeing. BTW, NYJimbo is one of the most knowledgeable and experienced techs here when it comes to MB repairs. Just so you know.

Maybe we need a new sub-forum for Motherboard repairs. I think it might be a good idea, but there are other forums with much more activity on the topic. One I follow but rarley post in, is the BGA Reballing Club.

 

[NYJimbo]

From my bench supply, as Larry has figured out, i have a multi adaptive end to fit any motherboard dc socket, I just plug it in and see if im getting current through from reading my PSU current display, if i see current getting in, then i know problem commonly on the board, if not, then socket is faulty, this just prepares me within few secs to tell costumer that it may well be a mobo issue and i would have to open it up to investigate, in this case it could be a lot of things but commonly bios or power circuit problems. Bga fault however will not stop current going into motherboard as you would see on the PSU meter reading display and also most of the time you will see some signs of life of power led or fans spin up and switch off. sorry lary if i waffled on a bit on this subject.

My point was if you are putting power into the jack but a fuse, cap, power mosfet, ferrite bead on the mobo (like on older dells) was blown right behind the jack you would not see a current draw. How do you tell its one of those circuits and not the DC jack in that case without opening it up and checking the board.

 

[Dee]

My point was if you are putting power into the jack but a fuse, cap, power mosfet, ferrite bead on the mobo (like on older dells) was blown right behind the jack you would not see a current draw. How do you tell its one of those circuits and not the DC jack in that case without opening it up and checking the board.

Absolutely right jim, thats why i mentioned that if no current is getting through, then i would notify costumer that you may have a mobo problem and that i would have to open it up to investigate, just like you say a fuse or so, for me, this immediately turns to mobo repair level be it just a fuse or so, this is still chip level repair and need to be charged accordingly, im just saying in a lot of cases using this method i suggest, eliminates dc socket troubles quicker thats all, its all about elimination process, yes in cases it could be the fuse or a short in this case it does fall into mobo repair level in which i will charge.