Technical Guide on How to Repair a Sound Amplifier

Sound Plant Restoration


After spending 3 years in oblivion this sound plant of the so-called "Chinese plants", came to my hands with the intention of being repaired since it has been in several workshops and in the hands of several technicians and none has been able to solve its failure and return it to its optimal performance.


This type of sound plants are generally simple and of a very fragile manufacture, only for sounds at home or any other of simple denomination, but not for professional use. Professional Sound plants are more powerful and their electronic components are also of a professional quality, their transistors and other components are powerful and with a lot of work capacity.


For the Repair of this type of Equipment it is necessary to have the appropriate tools and to have a deep knowledge in the matter to be able to solve the failure effectively.

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It begins by reviewing the Audio Output channels, and their controllers: this plant has two negative and two positive outputs on their respective left and right channels, A1941 and C5198, and its controllers are D667 and B647.


The rest of its components are common resistors that can be checked by removing them from the plate to obtain exact and correct measurements. The Main Filters (Electrolytic Capacitors) should also be checked, to know that the supply voltage of the board is in good condition.


Checking all the electronic components, I was able to find the output transistors faulty as well as their controllers, as well as two of their main filters. By changing them the fault was possibly solved. But the measurements kept giving an altered value, which led me to review more thoroughly and with success I was able to find that two Zener Diodes that feed the Right channel of the Audio outputs were in Faulty.


Replace the Zener Diodes and the measurements were accurate, voltage passed and the system active; I tried sound and everything was solved. Although it seems and sounds easy, it is not, because the most delicate work is to download piece by piece from the plate and measure them and thus know that they are in good condition, sometimes only one leg must be detached and thus obtain the measurement but there are transistors such as the "5551" and the "5401" that must be completely detached to obtain a good measurement with the multimeter.


Well this time there is another satisfied client and one less team that will end up in the trash and create pollution ... As I always say, if we could fix many things and create a non-consumerist consciousness, I think we would extend the resources of our planet and mother nature. did not suffer so much wear.



Greetings and I hope you like it ... Do not hesitate to comment or ask.

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