Power Jack on laptop and motherboard cleaning

Hi all

One of the guys at work brought in his wifes laptop.

The power jack has been iffy for ages. Had to wiggle it loads to get it to charge etc.

They just got back from holiday, leaving the laptop at home, to find it would not boot. No matter how much wiggling the power plug it wouldn't charge.

I've got no issue in replacing the power jack, it's £5 from fleebay.

I have taken apart the laptop and have a table full of parts.

Now upon disassembly I noticed lots of evidence of liquid residue.

I quizzed him and found out she'd spilt a glass of wine over it a year ago but it has been working fine ever since.

Now since the laptop has been working fine after this indecent I do not think it is related to the current won't boot issue.

Now i'm a clean guy, should I clean up the residue. A few of the tiny resistors have gone fury.
I have TIM cleaner and was thinking of using that. Otherwise I need to order some isopropyl alcohol.

What are peoples thoughts on cleaning the mainboard.

Ed

Why not just go over with a toothbrush or something similar? That should clean the fur off and avoid moving the residue around.

Is it easy to replace the power jack?

the first thing i would do is check whether the battery itself is knackered, dodgy charging can and will knacker them. as they have just come back from holiday, the charge in the battery could have dropped below the minimum level where the charger charges from.

-something about the internal resistance being to high for the amps going in, low voltages and such-

worry about the cleaning later.

Quote:

---

Originally Posted by stevie lee

the first thing i would do is check whether the battery itself is knackered, dodgy charging can and will knacker them. as they have just come back from holiday, the charge in the battery could have dropped below the minimum level where the charger charges from.

-something about the internal resistance being to high for the amps going in, low voltages and such-

worry about the cleaning later.

---

Hi

It wont boot with the battery removed either so i'm 99% certain that the power jack is at fault.

Ed

Some devices are just badly designed and don't always like to turn on with no battery in. If you leave it plugged in for a long time does it take any charge?

The power jacks can be a real PITA to replace unless you have eight pairs of hands, a clamp, some pliers and a really good soldering iron and some wick. I'd be inclined to check the connection with a multimeter before replacing it.

I have a feeling the corrosion of components is more likely to be an issue here.

The battery did not take charge over consecutive nights. The battery still had charge in when they returned from holiday but has been unable to recharge. It is now flat.

I have the laptop apart next to me and the parts should be with me in a couple of days.

I not have a multimeter at work to nest the old jack but there is enough play in the jack's internals to make me consider it FUAR. All the legs of the jack seem to be in good order. I have had the easy to diagnose snapped contact before.

Ed

Let us know how you get on please

My sisters dell laptop had a very similar problem, would take ages to get it to charge - Dell replaced the jack.

I'd look there first.

crush the old jack with some mole grips to shatter the plastic, then use some nail scissors to cut it apart so you can desolder one pin at a time.

just use a steady hand so you dont rip the pins out when you do it !

personally i use a hot air soldering kit to do it as you can take it out in one go.

Your diagnosis is probably correct, but have you checked to see if there is an output from the power supply. Sometimes the wire from the power supply to the computer can break if it has been mistreated or flexed excessively. Usually near the conntion jack - which would also give the symptoms you described)

As for cleaning, I would use IPA.

Quote:

---

Originally Posted by peterb

Your diagnosis is probably correct, but have you checked to see if there is an output from the power supply. Sometimes the wire from the power supply to the computer can break if it has been mistreated or flexed excessively. Usually near the conntion jack - which would also give the symptoms you described)

As for cleaning, I would use IPA.

---

I brought in my multimeter today to test out the power supply. No matter how I moved the cable i got a good reading. The cable is in very good condition.

I have ordered in some IPA too, now off to the supermarket to get a soft toothbrush........

Ed

Quote:

---

Originally Posted by GoNz0

crush the old jack with some mole grips to shatter the plastic, then use some nail scissors to cut it apart so you can desolder one pin at a time.

just use a steady hand so you dont rip the pins out when you do it !

personally i use a hot air soldering kit to do it as you can take it out in one go.

---

I was reading through some ''how to replace power jack'' guides. They go to such lengths to remove the old jack intact. Mainly because they say the jack is fine but the solder cracked. Seems daft to me since a dry joint can be easy to spot and all I would do would be to touch a bit more solder and heat to it to give good contact!!

Anyway I have every intention of clipping the component down to size before i desolder it. It makes the whole process easier.
I prefer holding the remainder of the leg with needle nose pliers, apply heat, then remove said leg while solder is molten. Use braid or pump to remove excess solder then insert your shiny new component and solder it in place.

Ed

good luck as its still very hard to remove even with a pump and braid, to much heat and you destroy the tracks.

although you have a good point about cracked solder, if the pin has not been knocked in a resolder is usually all that needs doing, scrape some more track to copper to allow extra solder for a better connection and it can give you years more trouble free charging :)

you can see if its worked by powering up the mobo while out the case or placing the battery in the contacts to see if the charge light comes on.

Quote:

---

Originally Posted by GoNz0

good luck as its still very hard to remove even with a pump and braid, to much heat and you destroy the tracks.

although you have a good point about cracked solder, if the pin has not been knocked in a resolder is usually all that needs doing, scrape some more track to copper to allow extra solder for a better connection and it can give you years more trouble free charging :)

you can see if its worked by powering up the mobo while out the case or placing the battery in the contacts to see if the charge light comes on.

---

I had a bad experience with one of my old Fujitsu laptops. I was trying to diagnose and issues with the fan not spinning so i booted with it effectively in a benching state and it fried the motherboard.

I'd rather not do that again especially since it is not my laptop :-)



ED

I got the old jack off today.

Old solder is a stubborn plus the stuff they used has tonnes of flux in !!

I'm going to get some braid to add to my kit. My solder pump was not very effective at getting the small volumes of solder off.

Anyway I cleaned it all up for the new bit that still has not arrived. Though I felt sick though the whole cleaning process since I really hate the smell of alcohol.

Lets just say Ed drank far to much Vodka one night long ago and can't stand the smell of alcohol ever since. What was more annoying was doing 2 years of organic chemistry where we used alcohol endlessly.

ED

Ok guys I need a hand.

I have replaced the jack with the shiny new one.

I tested the jack before installing and it was fine.

I have retested the power supply and it a 100% perfect reading.

I have not tested the battery, I need to find a few paper clips to give my multimeter some dexterity to get to the terminals first !! though I do not see how this would help since it has no charge!

I tested the jack once i had installed it and again got a perfect V reading.

I can not boot. Either with the battery in or removed.

So people what would be the next diagnostic check. I am leaning towards a motherboard failure prior to me opening it up.

Yes there was the wine indecent but If he has broke it with the wine he would have told me.

Any ideas please.

Ed