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LAPTOP REPAIRS

LAPTOP REPAIRS

I have a 10+ year old laptop that was slowly becoming less functional. The speakers were crackling quite loudly even at a lower volume, the hinges were loose, but recently when it randomly started shutting off very frequently, I knew it was time to either repair it or replace it. Since the laptop was a 17-inch model with a fast CPU and 24gb of ram, I didn’t actually want to replace it, so I opted to try and repair it instead. This repair saved me from having to spend $2000 to buy a new laptop of similar capabilities, and only cost me $8 (epoxy and minor stuff).

Step 1

Wearing a static strap, I disassembled the laptop to access the hinges and motherboard. Once I removed the top of the chassis, the keyboard, and the touchpad assembly, I could then access all the items I needed to repair.

Step 2

The laptop’s 19v power connector was intermittently causing the laptop to frequently and suddenly die without warning. The red screwdriver is pointing at the connector in the laptop. I used a multimeter set to the Ohms scale and checked resistance of each wire and conductor, and while wiggling things, I found that the two black wires did not have a consistent connection (would vary between 0.5 Ohms and infinity). I cut away the black heat shrink on the connection and found that the solder joint was broken.

Step 3

I resoldered the wire to the connector and put new heat shrink tubing over it. I then checked continuity again of all the connections while wiggling everything again. All was good.

Step 4

The laptop speakers started making crackling and buzzing noises a few months ago making it very hard to hear anything. A check of the speakers showed that the speaker front suspension (the “surround”) was torn on two of the four speakers.

Step 5

The torn surround meant that the speaker cone was able to move sideways and interfere internally which is what was causing the speakers to crackle. I could not find a suspension surround to buy for a small 0.5-inch diameter speaker like this, so I had to make my own. I experimented with two different types of tapes. With both tapes I made sure the adhesive side of the tape stuck to the highest part of the speaker cone so the cone could not float sideways at all. The two tapes that I tried were: Tape #1): On the first torn speaker (one of the two left stereo speakers), I used 0.75-inch wide matte finish scotch tape (common household tape everyone has laying around). I used this tape as it was 0.13 inches wider per side than my 0.5-inch diameter speaker cones, and so overlapped the speaker case enough to securely hold to it. I cut a semicircle on one end of the tape so it would lay flat without wrinkles on the thin side of the speaker case, but I left the other end of the tape square so I could hold it to position it carefully. Tape #2): On the second torn speaker (one of the two right stereo speakers), I used kinesiology tape because it stretches with very little force and so should impede the axial movement of the cone less than scotch tape. Kinesiology tape stretches easily in one direction but not the other, so I installed it in three strips positioned so that each strip had its stretchy direction mostly radially to the cone to allow the cone to move axially as easily as possible but hopefully still centring the cone radially well enough. The result was a cone that moved axially much easier than the scotch tape, so I thought it would sound better. Below are before and after photos of the application of the last of the three strips of tape.

Step 6

The hinges on the laptop had been sloppy for years, and you could see the chassis flex whenever you opened or closed the laptop. Once I removed the top of the chassis (the top that contains the keyboard), I found the metal hinge mount was no longer attached to the chassis bottom, as the plastic that held the brass threaded inserts was all broken, so there was nothing holding the screws to the chassis bottom anymore.

Step 7

Most strong, stiff adhesives do not bond well chemically to the plastic that the chassis is made of I discovered (after testing a few adhesives on it), so I had to apply any adhesive in a way that would have as much surface area in contact with the chassis as possible. I also needed to give any adhesive as much mechanical grip to the plastic as possible, so that the adhesive would be interlocked to the plastic mechanically, so I did this by creating rivets out of adhesive, and grooves in the chassis to ensure cured adhesive would not be able to pull away from the plastic. The adhesive’s mechanical gripping to the chassis means that the only way the cured adhesive could be pulled away from the plastic was if some of the plastic were to break away also, which means the strength of the bond to the plastic would be just as strong as the parent plastic itself. I removed the hinge bracket and all the broken plastic bits. To add grooves and roughen the plastic where the adhesive would be contacting, I used a rotary tool and a scriber. I trial fitted the steel brackets and brass threaded inserts to ensure they would locate themselves to exactly where they originally came from (mine had six alignment nipples that were partially intact still to align them with). I coated the screw’s threads with wax (I rubbed them against a wax candle) so that adhesive would not stick to them. I put the screws through to the steel brackets and threaded the brass inserts onto them by three threads only (the underside of the screw’s heads must not be contacting the top of the bracket, in order to ensure the threaded inserts would be contacting the chassis bottom while the epoxy is curing). I applied a high-strength (3960 psi) epoxy, that is iron filled (cures very hard), has a decent working time of 15 minutes, and a long curing time of 24 hours, to ensure as good a bond as possible to both the chassis and the bracket where they would contact each other. I placed the bracket into the chassis in its correct alignment position, then I pressed the bracket down to embed it into the epoxy. I then pressed down on each of the two screw heads to ensure the threaded inserts under them were contacting the chassis bottom and embedded in the epoxy. I left it to cure for 24 hours.

Step 8

After 24 hours, I tipped the laptop up vertically so I could pour epoxy into the cavity formed between the bracket and chassis (filling the cavity ensures that the brass threaded inserts will never be able to break free again, and also that the plastic chassis and steel bracket will act as one in order to minimize flexing at this high load point). In order to fill the cavity, I first had to seal off any gaps that liquid epoxy could leak out of. I used a fast-setting, four-hour epoxy for this, so that later I could fill the cavity with more high-strength, slow-curing epoxy without it being able to leak out of any small gaps during its 24-hour cure time. The fast-setting epoxy I used had a strength of 2420 psi, a fast-working time of six minutes, and a fast cure time of four-six hours, and is compatible with the high-strength epoxy I am also using. I used a dental pick and toothpicks to carefully apply the epoxy to the seams to make sure they were sealed. I left it for four hours to cure. Now that the seams were sealed with the fast-curing epoxy, I can fill the entire cavity with high-strength epoxy. I left the chassis in a vertical position still and filled the cavity with high-strength epoxy. I left that to cure for another 24 hours.

Step 9

Now that it was fully cured, I was able to move it and apply moderate force to it without worry of the steel bracket coming loose. I then created epoxy rivets to mechanically hold the bracket to the chassis. I did this by drilling through some of the plastic alignment nipples that pass through each bracket, using a drill bit diameter that was slightly smaller than the hole in the steel bracket. I drilled through the four nipples per bracket that were the furthest away from each other, being careful to drill through the plastic only and not the steel. I drilled each in three stages consisting of a very small diameter drill bit, then a larger drill bit, and then the final diameter drill bit, as this minimized the chances of a drill bit trying to cut into the steel bracket rather than just the softer plastic. I countersunk each hole from the underside of the chassis so that when I created an epoxy rivet head there, it would spread any load it carried over a larger area of plastic chassis and be less likely to crack the plastic when under load. I used scotch tape to form a pocket below the countersink, so that when epoxy flowed through the hole, it would not drip onto the table but would instead pool into the pocket and form a rivet head.

Step 10

I laid the chassis right side up on the table and applied the high-strength epoxy into the drilled holes by pushing it into the holes using a dental pick and a toothpick until enough had flowed through the hole to form a rivet-head-sized blob onto the scotch tape pocket under it. I repeated for all four holes of each bracket. I then smeared epoxy on top of each hole to form a rivet head 2mm thick as that was all the space I had to use before it would interfere with parts that would eventually be assembled above it.

Step 11

I smeared epoxy on top of the bracket to connect all the epoxy areas together (the four rivet heads, the cavity, and the epoxy on the chassis surfaces on all sides of the bracket). This would tie all the epoxy together so it acts as one to distribute the load from the bracket to the chassis. I left it to fully cure for another 24 hours. I removed the scotch tape on the bottom to now expose the epoxy rivet heads. I left it to cure for another eight hours just in case the scotch tape adhesive had impeded the epoxy surface curing where it contacted it. I removed the screws from both brackets and cleaned the mounting surfaces of both brackets with 100% isopropyl alcohol.

Step 12

I rotated each hinge on the display to ensure they moved properly and were not binding. One hinge creaked a bit, so I placed a very small drop of WD40 onto where the metal pieces met to help lessen the creak. I made sure not to drop any on any plastic or elastomers in the hinge as I did not know how it would affect their friction (the hinge needs to be stiff enough to hold the screen at whatever angle you move it to, but it cannot be too stiff or it will be hard to open the laptop’s display).

Step 13

I reinstalled the hinged display onto the steel brackets in the chassis with their four screws. I tightened the screws securely. I reinstalled the power connector receptacle using its original screw and bracket. I reinstalled the speakers. I reinstalled the top of the chassis with its original screws and attached its cables that I had previously disconnected. I then reinstalled the keyboard into the top of the chassis by snapping it into place after attaching its cables. Testing the Repairs After fully reassembling and rebooting the laptop, I tested the three repairs. 1. Power Connector: I wiggled the power connector in every direction and the laptop never lost AC power, so the repair worked. 2. Speakers: I went to a website that plays audio alternately out of both left and right speakers and found that both sounded good, although the left side was slightly louder than the right side, so it appears as though the scotch tape repair worked better than the kinesiology tape repair. Three weeks of constant laptop use later, I repeated the test and got the same results. So neither tape has lost adhesion from vibrations, etc. 3. Hinges: I moved the laptop display by opening and closing it many times including holding it at one corner while doing so, and the laptop chassis did not flex at all and the hinges felt extremely smooth and solid. Three weeks later it still feels completely solid and smooth and feels like it did when the laptop was new.

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