In the previous chapter 4, we discussed a little on how to detect common faults in devices much in a way a beginner can easily understand. In this and the next chapter, we will consider how to solve the faults we have detected earlier. Not all faults and solutions can be discussed in this textbook. In fact, if we are to discuss all, then we may have up to hundreds of chapter to contain them. have many articles that considers many of these errors and their solutions. These articles will be a great help both for beginner and the advanced repairers.

1. MIC

In MIC that are soldered to the PBC, note the two terminals of the MIC. Solder the red terminal to the positive (+) lead in the PBC and the black terminal to the negative (-) lead of the PBC. See chapter 1 for instruction on soldering. The soldering should be strong because after soldering, the MIC will be bent to its position. If not well soldered, the soldered terminal just soldered may cut out. As we have considered before, allow the soldering iron to be sufficiently hot before soldering and apply your soldering past. Avoid shaky hands.

Also notice that some two terminal MIC may have black and blue colored terminals. In that case, the blue is the positive while the black is the negative(-).

In MIC with four terminals such as those found in TECNO PCB, much about this will be discussed in the next section. Fixing them may not be too easy for the beginner as they are not easy to fix. Another difficulty that may arise is that while trying to replace it, a repairer may end up pulling its led from the PCB. This is really a complication that a beginner should really avoid. .


The same principle of fixing a MIC is also the same in fixing a speaker. In china device, while the notation for the MIC is “MIC+” and “MIC-“. The notation for speaker is “SPK+” and “SPK-“. If a speaker is an insertable speaker, then there would be no need soldering it to the PBC of the device. Just insert a new working speaker in place of the old faulty one.

Sometimes, it happens that the speaker has been replaced with a working one but still not producing sound. What then? One possibility is that the connection way of the speaker in the PCB is broken and at this time you cannot trace it. There are solutions for these issues and most of them can be found online in sites that provide such solutions. It is simply re-establishing connection with the use of jumpers. The picture below shows a PCB with the speaker connection way broken. Note that this can happen to any other component in any PCB at anytime.


The MIC, speaker and ear piece all has the same way of fixing. But the MIC is not insertable in any device. It must either be soldered or heated to the PBC. The ear piece and the speaker can be soldered in some device or just inserted in some other devices. The notation for the ear piece is “REC+” and “REC-“.


In few devices like some blackberry, it is inserted in it fixed position, while in many other devices, it is soldered to the PBC. If one or more out of the three terminal get broken, especially the positive and negative terminal, the device will never turn ON and replacement will be needed.

For a beginner, great care and attention is needed here if you are fixing the battery terminal for the first time. The reason is because removing the faulty terminal can pull the led on the PBC off and prevent new working terminal from working. Although if this happens, an alternative connection can be created and the device will work just fine, we want to avoid this.

Now to begin, turn the PBC to its back and check if there are no component at the back of where the battery terminal is soldered to the PBC. If non, then heat the terminal from the bottom until it falls off or removed. Do not do this if there are components at the bottom of the terminal at the other side of the PBC as those components will fall off and damage the device. If the terminal could be heated out, replace a new terminal by first soldering the protectors before soldering each terminal contact. This is a general principle.

Few more methods of replacing the battery contact will be considered in the next section.

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