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Audio equipment
Sony MHC-AG551S
26
hace 6 años
hace 6 años
Hello friends, nice to greet you. I am repairing a mch-ag551s sound system. It does not turn on and the stamby LED flashes, I proceeded to disassemble and desolder the integrated Stk, once done, I reconnected everything and turned on and I find that the ssigu led flashing, these equipment includes two integrated, one for the outputs of audio and an additional one for the Subwofer, I proceeded to disconnect the Subwofer board, and turned on the equipment and started correctly, proceeded to remove the STK from the Subwofer board, and turned it on again and the same problem, it was protected again, with This ruled out that it was the STK of the Subwofer and I began to measure components, I found that the fuse resistor R509 was open to replace it and kept looking for bad components and I couldn't find any of irregular values. What can I do to discover the fault on this board, it is worth mentioning that if I break the protection line the equipment starts normally. I hope you can help me
9.700
hace 6 años
hace 6 años
Josue if I'm not bad the team model is badly copied; Here you download the diagram:
https://elektrotanya.com/sony_hcd-gx750_rg551_rx550.pdf/download.html#dl
The line that you loose is pin 5 of the CN502 connector?
26
hace 6 años
Hi Evelio, thank you very much for answering the question. Well, the model that the team has is the AG551S, possibly because of the region because the model is like that, but it doesn't matter the diagram I've been using is the Evelio share. As the line is that same my dear. But I already found the solution to the problem. I have reinstalled the stk403-130 which is the one that makes the amplification of the Left and Right outputs of the speakers, and I have left the Subwofer module disconnected and the equipment starts normal, it should be noted that it did not give sound but it was due to the resistance of 100ohms R496.
26
hace 6 años
hace 6 años
As for the Subwofer module, I can verify that the stk404-130s is shorted internally and for that reason the equipment is protected, but it should be noted that if one solves this stk we would expect the equipment to turn on as it normally does but in this case it is not Thus, in the line of the overload / dc which is responsible for detecting faults, it has several transistors at its disposal and specifically the Q507 has its base connected to a resistance to GND which is internally in the stk, as it is not present The stk said base line is connected to the R530 which sends the 11.9 based on what the transistor does start driving 11.9 vdc on the line that is used as protection and therefore the equipment is protected. Now, I would like to try another stk404-130s that is in good condition but unfortunately I have not yet found one, possibly touch buy it online. When I put it in and the equipment arrives to work well in its entirety I will close the question as solved.
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