laptop repair

Laptop Repair Samsung NP-RV511

This laptop was found to be not working, since a young child trod on the charging lead. Unfortunately, it damaged the power connector and it was no longer able to charge. When trying to charge it made a burning smell. Looking inside the connector, the plastic that insulates the positive and negative terminals had cracked off, meaning it could go short circuit.

This particular laptop repair was going to have to be done on the motherboard. This model of Samsung laptop is a mid range machines and is worth fixing
I tested the output voltage of the PSU and battery, which were fine. Luckily the short circuit did not damage the battery charging circuitry with a current surge.

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I opened the laptop and as expected, I had to remove the, heat sink, fan, and motherboard, just to be able to get at the power connector. Credit to Samsung usually, I like working on their laptops and have repaired a few of their devices now. However, they decided to hide screws under the rubber feet this time. We can only hope Samsung don’t go down this road in future, and make laptop repair more difficult.

ImageI started de-soldering the connector with the iron but it was a real nightmare to get the solder out. As this was a multi-layer circuit board, as soon as I removed the iron to get the solder pump in, it lost temperature very rapidly and I could not remove the solder from inside the joint. The internal traces were soaking up the heat so fast I couldn’t get the solder pump to the surface fast enough after the iron was removed.

After half hour, I realised I would need more tools. I took the board home and I had to get the hot air rework station on the go. The air gun is great for reworking newer surface mounted components and whilst the power connector was through hole, I now had the means for a two prong attack.
I heated the connector with the heat gun but then I noticed a tiny capacitor sitting on the board. I applied some heat proofing tape around this and then proceeded to heat the connector.

You must be very careful when working with surface mounted components as stray heat can dislodge neighbouring components, so it is essential you use some kind of heat proofing.

With the other hand, I used the iron to rapidly heat the solder joints. Now they were looking nice and molten and it was simply a case of keeping the temperature up. I attached the hot air gun to a stand pointing on the area at 300 C, and then it was a case of de-soldering each pad, with the hot air to keep the temperature up. ImageLo and behold, this method worked great and all the trouble I had de-soldering had been removed as the internal traces did not have chance to suck away the heat before I could get the solder sucker in there.

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I used so much flux getting the solder to melt it left marks all around the connector. Flux left on the board can eat through the solder mask and potentially corrode the traces over time so it is essential to remove it. I used acetone and cotton wool buds to remove the flux, you have to make sure you do not rub the bud from side to side or else you leave cotton strands which catch on sharp edges. These fibres can cause short circuits so it is best to use a circular motion.
Then it was a case of soldering on the new component. This was very easy and it did not require all the effort I went to removing the component. I simply increased the iron to 480 C and this heated the component leg perfectly, allowing the solder to flow through the joint nicely. After checking the connector was positioned flush with board it was time to reassemble the laptop.

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Thankfully, it went together nice and easy and tested fine on start up. The laptop repair was completed, and it was ready to return to service.

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