Jordan Haining
New Member
Hello,
I will start by saying I have a fair bit of experience troubleshooting both in past jobs and at home as a hobby but not a whole lot with audio. I am now in school to become a refrigeration and A/C mechanic and have also learned extensively about troubleshooting of refrigeration controls so I am familiar.
My Technics SA-DX750 Receiver is having issues. During playback it suddenly gets distorted then the audio cuts out. There doesn't seem to be any overloads tripped because everything other then the sound seems to work. It affects signals coming in both the digital and analogue inputs so I don't think it is the digital circuit. Sometimes it will play for over an hour then crap out other times only a couple seconds. I found the repair manual on manualslib and have been reviewing it. It affects all the speakers so that leads me to believe its not either of the main amps (1 for Front L/R and 1 for Rean L/R and Centre). I have followed the traces on the schematic and it appears the 2 components all channels share are IC401 TC9164AN Switch Array. and IC402 NJM4580DD Op Amp. They then go through their respective circuits and to their respective inputs on the main amplifier IC's. The problem is I do not own an oscilloscope and cannot look at the waveform, is one necessary or can I troubleshoot audio circuits with a DMM. Also does it sound like this could be the issue. I just don't have the money to take it to a repair shop or to buy a replacement amp. Any other suggestions would be appreciated.
Thanks Jordan.
Edit: I forgot to mention all the caps look good, none of the look like the are broken and the PCB around all of them is clean.
I will start by saying I have a fair bit of experience troubleshooting both in past jobs and at home as a hobby but not a whole lot with audio. I am now in school to become a refrigeration and A/C mechanic and have also learned extensively about troubleshooting of refrigeration controls so I am familiar.
My Technics SA-DX750 Receiver is having issues. During playback it suddenly gets distorted then the audio cuts out. There doesn't seem to be any overloads tripped because everything other then the sound seems to work. It affects signals coming in both the digital and analogue inputs so I don't think it is the digital circuit. Sometimes it will play for over an hour then crap out other times only a couple seconds. I found the repair manual on manualslib and have been reviewing it. It affects all the speakers so that leads me to believe its not either of the main amps (1 for Front L/R and 1 for Rean L/R and Centre). I have followed the traces on the schematic and it appears the 2 components all channels share are IC401 TC9164AN Switch Array. and IC402 NJM4580DD Op Amp. They then go through their respective circuits and to their respective inputs on the main amplifier IC's. The problem is I do not own an oscilloscope and cannot look at the waveform, is one necessary or can I troubleshoot audio circuits with a DMM. Also does it sound like this could be the issue. I just don't have the money to take it to a repair shop or to buy a replacement amp. Any other suggestions would be appreciated.
Thanks Jordan.
Edit: I forgot to mention all the caps look good, none of the look like the are broken and the PCB around all of them is clean.