This tablet repair was needed as the charging lead was not working correctly. It had to be held at an angle in order to try and get an intermittent charge. Upon inspection, the plastic inside the micro USB port had broken, and the pins were bent out of shape. It was a case of opening it up and soldering a new one on to the mother board.
It was straightforward to work on and I have done a teardown guide for it on I fix it. However, this is not to understate the difficulty in performing this procedure. It actually took me a lot longer than anticipated as it was so fiddly. Just to give you an idea, essentially you have to tin 5 copper pads that are less than 1mm thick, and are less than 1mm apart.
On the third attempt I got it almost spot on with only pins 4 & 5 shorted.
After getting the board out I had to clamp it in a vice and identify any problem areas. On the underside of the board there were surface mounted components. If any heat got near these it could dislodge the components and ruin the board. I had to make sure they were protected with heat proof tape so that they were protected.
I started de-soldering the connector with the iron but it was high temperature solder. As this was a multi-layer circuit board too, it lost temperature very rapidly as soon as the iron was removed, and I couldn’t get the solder pump to the surface fast enough.
In order to remove the solder from the 5 pins I had to use desoldering braid and keep applying heat gently in order to mop up the solder. This was laborious and very time consuming. After this was done I had to use the old combination of hot air gun and iron to melt the solder and remove the USB port.
After screwing around for ages I managed to get the usb port off but unfortunately one of the traces had started to delaminate. Fortunately, the connection was still good and it had only lifted on the edge. I managed to move it back in place with a spudger and it was fine.
Then it was a case of installing the new one. Easier said than done. When you buy a cheapo soldering iron they usually come with a useless concial tip. However, this was one instance where a conical tip was perfect for the job. Since the copper pads were so small, this was the perfect size for precision soldering.
Soldering Micro USB Port
I tinned the 5 traces but as they were so close together the solder spilled over on to the next pad. By dragging the iron along the trace I was able to get it flowing on its own pad and managed to get it neat. Then it was a case of using the hot air gun and tweezers to try and get the port in position. The mounting holes locked it in position but if there was a slight angle when lowering it in place it would cause the terminals to bridge. I got it in place but the pins were shorted together. I had to start the process again.
On the third attempt I got it almost spot on with only pins 4 & 5 shorted. By dragging the iron along the pins I managed to get the solder to flow on to its respective pad. Then it was simply a case of soldering up the mounting pins, and clearing up all the flux residue with acetone. Excess flux can eat through the solder mask and copper so should be removed to ensure long life.
Testing The Tablet Repair
As the pins were so tiny it was virtually impossible to run a continuity check without some kind of gadget to do so. I cut a usb cable in order to do this test and I inspected it with a magnifier. It looked spot on and tested OK so I rebuilt the unit and plugged it in. Naturally, I was very relieved to see the charging sign on the front of the display when the power was applied, and the job was good. It fully charged the unit and appeared to be working fully.
One of the most fiddly repairs I have attempted but it was very satisfying to perform this intricate type of surgery. If you can do this, I guess you would probably have not been too bad at heart surgery too!