I'm trying to repair my laptop (sparks and smell of smoke) - Page 1
Forum section: electronics / beginners

author: ziegler
author_rank: Regular Contributor
timestamp: February 12, 2015, 01:01:00 pm
content: I looked at this videoSo my old laptop stopped receiving power from the powerjack, if i used some time turning it just right, it would get power.But since the last time I did it, it haven't worked agian.There for I thought that it was the laptops powerjack that was the problem.I removed all the parts from the laptop, so I could get to the motherboard.Then I plud in the power jack, used my multimeter to see if I got any power, it didn't.When i looked at the multimeter's screen, I think I unfortunately moved the 1 probe over the metal case, because there was 'sparks' and 'the smell of smoke', coming from the motherboard.(the multimeter looks like it still work)Not sure if you can tell what/how/why it happened, but I would love to know.

author: sean0118
author_rank: Frequent Contributor
timestamp: February 12, 2015, 01:21:29 pm
content: You've shorted something out. Either the multimeter was in current measuring mode or you've bridged across something with one of the probes. If your really lucky it might have just opened a fuse, post some pics of the motherboard...

author: ziegler
author_rank: Regular Contributor
timestamp: February 12, 2015, 02:52:58 pm
content: I'm kind of sure that it wasn't in current mode (the positive probe was in V).as you can see on the photo, the plug is close to the metal case.it doesn't look like any of the fuses are burned out.

author: ziegler
author_rank: Regular Contributor
timestamp: February 12, 2015, 03:44:50 pm
content: I tried again, the sparks (no smoke this time) happens when both probes touch the same metal pin, from the power plug.Look at the photo, the 3 pins from the plug, will be name (from left to right) = 1, 2, 3.When I probe pin 1 and pin 2, I get 19 V and when the probes touches, the front LED lights up, indicating that the motherboard get power, but only when I probe pin 1 and 2.Touching pin 1 and 3 gives nothing, the power supply doesn't have a 3 legged cable l ( not sure if pin 3 is for ground or not )I have seen that some people have fix the plug by desoldering it off from the motherboard and resolder it back on again.after what I have said here, do you think that it could work ?

author: PA0PBZ
author_rank: Super Contributor
timestamp: February 12, 2015, 03:51:46 pm
content: It looks like you can resolder the pins without taking the board out, I'd certainly try this first.Unplug the power, take the battery out and heat the 3 pins, maybe add some additional solder.Plug the battery and the power back in and hold your breath...

author: ziegler
author_rank: Regular Contributor
timestamp: February 13, 2015, 11:12:29 pm
content: So I think that I made it worse, as you can see on some on the Photos.I only have that 1 big tip for my iron, also pick a weird soldering-wire (it will kind of sticks to the iron after you lift it up).I think all the 'rose' around the pin hole, is gone now.The motherboard is now discolored.Can't get the old readings from my meter to show again, but every time I connect the plug inside, the LED lights up 1 time, and turns off again after.

author: ziegler
author_rank: Regular Contributor
timestamp: February 13, 2015, 11:18:17 pm
content: Maybe I need to buy a new plug to replace the old one, not sure if it will work.

author: rexxar
author_rank: Frequent Contributor
timestamp: February 13, 2015, 11:20:18 pm
content: You've just shorted your power supply. You said you get 19V between pins 1 and 2, and now they're shorted together with a giant blob of solder. Get some flux and desoldering braid/wick. Wick up as much solder as you can, then apply flux and try to solder it again.Are you using a proper temperature-controlled soldering station?

author: ziegler
author_rank: Regular Contributor
timestamp: February 13, 2015, 11:24:59 pm
content: You can see some small gold colored dots on the new Photos, which isn't on the first one.Some of them, if not all of them, was around the spots that made sparks come from my second probe, at the same time my first probe was on pin 1.

author: sean0118
author_rank: Frequent Contributor
timestamp: February 14, 2015, 02:25:23 am
content: Quote from: ziegler on February 13, 2015, 11:24:59 pmI can't see what you mean, is it just flux from the solder?Also like rexxar said, you've shorted out the two pins with solder. The power supply is probably reaching a current limit then turning off - or it's fried.You really need to take the motherboard out, remove the old solder from the connector using solder braid and resolder with fresh solder. What soldering iron are you using? Be careful not to overheat it, otherwise you'll lift a track and you won't have anything to solder too.

author: robgambrill
author_rank: Contributor
timestamp: February 14, 2015, 03:57:50 am
content: Just a word of caution.On a number of occasions at work we have had customers try to do this type of repair and mix up the screws, if you are not careful you can push a longer screw through an important piece of the laptop just by tightening it up. Modern laptops usually only have one or two sizes, but older ones can have half a dozen different lengths. Also it can just be hard to remember where they go if it takes a long time to repair the power problem. I usually just draw little boxes on a piece of paper and write down where they go or draw a little diagram. Set the screws right on your notes. That way you have something to jog your memory when it comes time to reassemble.When you have the board out, clean up the excess solder from your repair attempt. Then flip the board over. Look to see if one of the pins is sitting in the hole of a little donut of melted solder. I see this from time to time, I THINK it is caused by overheating due to a bad connection. If it is like this it will spark if you wiggle it powered (I try not to do that). Remove power and resolder the joint.If you still don't get power across the board (anywhere but the jack), it is probably a mechanical failure of the jack. I usually test with a voltmeter from the fuse to the ground shield so I am not touching across the pins with the meter probes.If it is a bad jack, apply ChipQik (it is stuff that lowers the melting temperature of the solder) and then use desoldering braid to remove the solder from all the holes to free the pins. I find the special alloy (chipqik) makes this job much easier. Because of the ground planes and the jacks shield, it is very hard to get to the normal melting temperature of the solder without damaging the copper PCB pads. ChipQik is your friend.When they made your motherboard at the factory, they soldered it together by essentially sloshing molten lead over the bottom (in a very controlled way). It was not made to be fixed, it was made to be inexpensive to manufacture. You are the first person to probably ever touch that jack with a soldering iron, don't get frustrated.Don't force the pins out, or wiggle the jack to get the pins out. You don't want to pull the hole plating out with the pin of the old jack. Seen people do that too! Be patient and take a break if it is hard to get the solder out. Sometimes, actually resoldering the pin and then trying with braid again will help wick out the hole.Soldering in a new jack is much much easier than removing the old one, just use flux and try to be neat about it. Small chisel tip would be better than the large one in your photo.If you succeed you saved your laptop, if not you probably would have had to spend 75 to a hundred bucks to have somebody like me do it, so it might not have been worth fixing anyway. It looks old just from the dust. I would definitely clean up the fan(s) and heat sink with canned air before reassembly if you get it working.Hope that helps a little, I do them all the time at work. The first few were hard, but it got easier with practice. Slow down and be careful. Good Luck with your repair!

author: G7PSK
author_rank: Super Contributor
timestamp: February 14, 2015, 09:43:49 am
content: Before you replace the power socket on the board it would be an idea to try another power supply. Many laptops have a sense pin as well hence the 3 pins on the socket. I have had laptops do the loose connection thing and it was the sense wire from the power supply that was fractured and making intermittent contact.

author: ziegler
author_rank: Regular Contributor
timestamp: February 14, 2015, 10:16:09 am
content: I found these flux pens, but i'm not sure which I should buy.-http://www.tme.eu/en/details/topnik-a3/fluxes/amtech/#-http://www.tme.eu/en/details/kes-952-d6/fluxes/kester/952-d6/#Been looking for a smaller tip for my iron, but unsure if it can fit in my iron-station (Weller WS 51 / Weller PU 51)-http://www.tme.eu/en/katalog/#search=weller+Soldering+tip&s_field=accuracy&s_order=DESC&id_category=100605&visible_params=2%2C1557%2C1558%2C1556%2C1560%2C1563%2C870%2C1624%2C823%2C1561%2C1562%2C1597%2C1595%2C1593%2C1578&used_params=2%3A45292%3B-http://www.tme.eu/en/details/plato-ew-511/soldering-tips/plato/ew-511/#-http://www.tme.eu/en/details/plato-ew-513/soldering-tips/plato/ew-513/#-http://www.tme.eu/en/details/plato-ew-515/soldering-tips/plato/ew-515/#-https://www.elfaelektronik.dk/elfa3~ex_en/elfa/init.do?item=82-454-09&toc=19761-https://www.elfaelektronik.dk/elfa3~ex_en/elfa/init.do?item=82-460-01&toc=19761What size of desoldering braid/wick should I buy ? 0,8 mm or 2 mm ?-https://www.elextra.dk/main.aspx?page=article&artno=H39763-https://www.elextra.dk/main.aspx?page=article&artno=H21816

author: ziegler
author_rank: Regular Contributor
timestamp: February 14, 2015, 10:23:01 am
content: Quote from: sean0118 on February 14, 2015, 02:25:23 amWeller WS 51 / Weller PU 51Use it at 250 C or 350 C temperature.Quote from: sean0118 on February 14, 2015, 02:25:23 amI think that the track is gone already, that small metal ring around the pin hole.It is all burned out and got a rusty color.Can it be replaced somehow ?

author: sean0118
author_rank: Frequent Contributor
timestamp: February 14, 2015, 01:21:27 pm
content: Quote from: ziegler on February 14, 2015, 10:16:09 amI have the WES51 which I like, if you remove the tip it should have a model number on there, they come in series starting with two letters such as LT, NT, ET etc. If you get a tip that's in the same series it should work, but I think they might also come in lead and lead-free versions depending on the type of solder you use.Quote from: ziegler on February 14, 2015, 10:16:09 amI would go the 2mm, or both if they are a good price.Quote from: ziegler on February 14, 2015, 10:23:01 amIs the copper still there though, or has it lifted off the board? If it's just burnt with flux and solder it will clean up with the solder braid. If you do overheat it and the pad/track lifts off it can't be replaced. But if your lucky there might be a pad on the other side of the board to solder too, but that's not ideal at all so be careful not to lift the track...edit: Also, with your Weller, do you mean it's adjustable between 250C and 350C? It's just that 250C is too cold and 350C is getting too hot, I would try and have it around 300C-320C, someone else on here would probably have a better idea then me though.