Hey audiokarma,
Seems like this is a fairly common problem, but I'd appreciate some guidance on how to go about fixing this so I don't damage this unit any further.
I picked up a Pioneer SX-980 on ebay a couple of weeks ago, and it's in incredible condition. And while it was working, I was absolutely blown away by how much better my setup sounds with adequate power. The guy found it at a garage sale and said it looked like it had sit in a room untouched for 25 years. He went through and cleaned it all up and deoxed everything. When I received it, I was actually blown away by how great of a condition it's in. Good stuff.
Problem is that not too long after I got it, I go to turn it on, and nothing. I noticed there was no usual click, so I got to researching how these things work and discovered the protection circuit and what it's functionality is, and what might be wrong with it. If I understand correctly, either the protection circuit is doing its job and protecting the speakers from some erroneously high voltages, or the protection circuit itself is malfunctioning and erring on the side of caution by ensuring that the speakers get no output.
I'm fairly confident that the latter is the case, because the day after discovering this problem, I plugged it in again and gave it a go. Sure enough, it clicked, and with FM input selected, the power meters came to life. Nothing out of the ordinary; volume was down fairly low and they jumped up the appropriate amount. But a few seconds later, it clicks again and they fall silent. Bummer! I haven't gotten it to click again since then.
I exchanged a couple emails with the guy who sold it to me, and he pointed me towards the fuses on the power supply board. I checked all of them and they appear to be in working order. He was very sympathetic and was pretty helpful in pointing me in the right direction, but I don't exactly want to burden him with guiding me through the repair of a unit he's already sold, of course.
In any case, I purchased myself a digital multimeter, and I have a soldering iron available to use, so I'd really like to get this fixed myself. I could take it in to a repair shop, but I figure that if I'm going to own old equipment, I better learn to take care of these kinds of issues because they're bound to happen again.
I read through some threads about this issue, and I checked pins 3 and 8 on the protection circuit, and they both read somewhere in the 100-150mv range. What I understand is that this indicates that the protection circuit is falsely engaged (correct me if I'm wrong). This reinforces my inclination that the protection circuit is the issue.
It seems there are some folks on here who are happy to help, so I'd much appreciate some guidance on how to go about diagnosing this problem. I have some experience soldering and working with computer assembly, but I haven't done much in the way of working with audio equipment. But like I said, I'm eager to learn how to care for this unit.
Cheers!
-Greg
Seems like this is a fairly common problem, but I'd appreciate some guidance on how to go about fixing this so I don't damage this unit any further.
I picked up a Pioneer SX-980 on ebay a couple of weeks ago, and it's in incredible condition. And while it was working, I was absolutely blown away by how much better my setup sounds with adequate power. The guy found it at a garage sale and said it looked like it had sit in a room untouched for 25 years. He went through and cleaned it all up and deoxed everything. When I received it, I was actually blown away by how great of a condition it's in. Good stuff.
Problem is that not too long after I got it, I go to turn it on, and nothing. I noticed there was no usual click, so I got to researching how these things work and discovered the protection circuit and what it's functionality is, and what might be wrong with it. If I understand correctly, either the protection circuit is doing its job and protecting the speakers from some erroneously high voltages, or the protection circuit itself is malfunctioning and erring on the side of caution by ensuring that the speakers get no output.
I'm fairly confident that the latter is the case, because the day after discovering this problem, I plugged it in again and gave it a go. Sure enough, it clicked, and with FM input selected, the power meters came to life. Nothing out of the ordinary; volume was down fairly low and they jumped up the appropriate amount. But a few seconds later, it clicks again and they fall silent. Bummer! I haven't gotten it to click again since then.
I exchanged a couple emails with the guy who sold it to me, and he pointed me towards the fuses on the power supply board. I checked all of them and they appear to be in working order. He was very sympathetic and was pretty helpful in pointing me in the right direction, but I don't exactly want to burden him with guiding me through the repair of a unit he's already sold, of course.
In any case, I purchased myself a digital multimeter, and I have a soldering iron available to use, so I'd really like to get this fixed myself. I could take it in to a repair shop, but I figure that if I'm going to own old equipment, I better learn to take care of these kinds of issues because they're bound to happen again.
I read through some threads about this issue, and I checked pins 3 and 8 on the protection circuit, and they both read somewhere in the 100-150mv range. What I understand is that this indicates that the protection circuit is falsely engaged (correct me if I'm wrong). This reinforces my inclination that the protection circuit is the issue.
It seems there are some folks on here who are happy to help, so I'd much appreciate some guidance on how to go about diagnosing this problem. I have some experience soldering and working with computer assembly, but I haven't done much in the way of working with audio equipment. But like I said, I'm eager to learn how to care for this unit.
Cheers!
-Greg
