Hi everyone:
New to the forum! Been buying up some older audio the past year and really enjoying the vintage sound. I'm a handy guy but have limited experience in troubleshooting/repairing electronics but I am eager to learn as I would like to make this more of a hobby (much to the wife's dismay) 🙂
Anyway, I have Pioneer SX-636 that has twice over the past 2 weeks produced a extremely loud hum from the left speaker. The first time it blew the woofer. I ended up Deoxing the A/B switch and popped on a older pair of speakers and no more hum. So I figured the woofer was at fault. Well happened again 2 days ago. I popped the cover took some reading at the speaker terminals and left channel was 190mv right channel 7.5mv. I did a quick visual inspection of any obviously bad looking caps but everything looked ok. took some additional readings this morning and left was at 0.17V, right at 8.1mv. Hooked the old speakers back up and no hum, have it playing right now and all seems good. It's been very humid and rainy here the past few days and thought maybe it might be a bad solder or cracked board. I also have read that "differential pairs" of transistors may be a culprit. I have a schematic but have no idea where they might be.
Sorry for the long post but if anyone has any ideas for additional troubleshooting that I could try it would be greatly appreciated. I don't have much testing equipment but might be willing to buy if needed.
New to the forum! Been buying up some older audio the past year and really enjoying the vintage sound. I'm a handy guy but have limited experience in troubleshooting/repairing electronics but I am eager to learn as I would like to make this more of a hobby (much to the wife's dismay) 🙂
Anyway, I have Pioneer SX-636 that has twice over the past 2 weeks produced a extremely loud hum from the left speaker. The first time it blew the woofer. I ended up Deoxing the A/B switch and popped on a older pair of speakers and no more hum. So I figured the woofer was at fault. Well happened again 2 days ago. I popped the cover took some reading at the speaker terminals and left channel was 190mv right channel 7.5mv. I did a quick visual inspection of any obviously bad looking caps but everything looked ok. took some additional readings this morning and left was at 0.17V, right at 8.1mv. Hooked the old speakers back up and no hum, have it playing right now and all seems good. It's been very humid and rainy here the past few days and thought maybe it might be a bad solder or cracked board. I also have read that "differential pairs" of transistors may be a culprit. I have a schematic but have no idea where they might be.
Sorry for the long post but if anyone has any ideas for additional troubleshooting that I could try it would be greatly appreciated. I don't have much testing equipment but might be willing to buy if needed.
It's time to restore the old girl, and get rid of all the light blue electrolytic caps, and some known problem transistors. I was going to suggest you head over to Audiokarma, but I see you've already posted there.
Welcome to the forum BTW.🙂
jeff
Sending her to the pro’s seems to be the consensus. Would love to get some experience but I guess I could save that for a dead system to play around with.
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