r/AskElectronics • u/svetsare • 15h ago

Broken Yamaha AX-500 Amplifier Preamp

Hello! To start, I don't know much about audio or electronics, this is my first amp and I got it very cheap as it has issues. But I would like to learn.

Currently the only way to use my Yamaha AX-500 is with the CD input and CD-direct toggled. No other input works as it should, BUT sound can be heard if the volume knob is turned near max, on all inputs.

During my first troubleshooting, the CD-Direct light turned itself on at high volume on the Tuner input and off at low, but I haven't been able to reproduce this.

Here's what GPT has helped me understand (spare me for using gpt): The problem lies in the preamp section as CD-Direct bypasses this. • Could be due to Faulty or dead preamp IC • Cold solder joints or broken traces in the tone/loudness circuits • Muting circuit partially stuck, reducing signal level • Faulty voltage regulation to the preamp section

I'd like to hear your opinions, how hard would it be to fix this? Can someone skilled with electronics attempt it?

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u/scsc1217 14h ago

Recently, I repaired a broken amplifier speaker that only produced faint sound. The issue turned out to be faulty coupling capacitors, so I replaced around 10 of them, and it started working fine again. I suggest disassembling the unit and measuring the capacitors' values first to see if that's the cause.