Well, I bought a preamp board from AliExpress, hooked it up, and was delighted with it for the last two weeks--very nice sound for the price. This morning I went to turn on the system and, though the preamp was on (the power LED is lit up), the volume was SO low even at full volume I could barely hear it, though I could hear something.... What are the first things I should do to troubleshoot what the problem is? Thanks in advance for all your help.
Is it colder now in your room than last week?
Solder joints often fracture at temperature extremes.
Solder joints often fracture at temperature extremes.
I think it might be that. Because after fiddling with the leads it started working again. I am going to resolder leads.
The first thing electrically to always verify the proper functioning of, is the power supply. I mean, after you’ve checked all wire interconnects for a secure connection, and the things which adason suggests above. You want to verify that all supply rails are at the correct voltage. This will be difficult, to impossible, to perform unless you have a working understanding of electronics, and even then, you may require the schematic.
If the rails are at the proper voltage, one of the, undoubtedly present op-amp chips may have failed. The fact that you hear music faintly playing could just be because it is still being conducted through the signal path via an op-amp feedback resistors, even though the op-amp itself might be dead. However, you’re now at the level of requiring on oscilloscope and electronics knowledge with which to intelligently probe around. One of the convinces when troubleshooting unfamiliar stereo circuits is that the opposite channel gives you a copy to refer to when probing. IF, you have the schematic.
If the rails are at the proper voltage, one of the, undoubtedly present op-amp chips may have failed. The fact that you hear music faintly playing could just be because it is still being conducted through the signal path via an op-amp feedback resistors, even though the op-amp itself might be dead. However, you’re now at the level of requiring on oscilloscope and electronics knowledge with which to intelligently probe around. One of the convinces when troubleshooting unfamiliar stereo circuits is that the opposite channel gives you a copy to refer to when probing. IF, you have the schematic.
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