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Weird Pioneer SX-1010 Volume Fading Problem

Ben Rothman

Ben Rothman

Active Member
Hi guys, I have a restored SX-1010 that I have used for about a year since the restoration. It got the works during the restoration, including the brand-new power supply board. It's been working flawlessly until recently when the sound started to fade in and out for no reason. I immediately thought it was dirty switches and cleaned everything (minus the pots), but the issue persisted. The volume and balance pots were smooth as silk and made no noise when operated, so I didn't think that was the issue. I eventually cleaned the volume and balance pot and the issue went away, sort of. When I let the unit sit overnight, if I turn it on, I get no sound out of the left speaker at extremely low listening volumes, but the sound does come out of the right channel. If I turn the volume up a tiny bit, the sound kicks in on the left channel, and it doesn't seem to go away. It will even work at the very low listening levels where it wasn't working before.

So I cleaned the volume pot again with Fadbrlube, and that fixed the problem right away, but if I let it sit overnight, the same issue came back in the morning on the left channel. If the volume pot is dirty, I don't get how moving it the most minuscule amount makes sound come through on the left channel, and then it works at the volume where it wasn't working before. I have sourced a replacement ACV-134 volume pot, and it's on the way. I'm unsure if the issue is in the volume pot, but I think it is. No other switch can get the sound to come back in except the volume knob.

I've read that the pre-out/main-in jacks could be dirty, and I haven't tried cleaning those, but I wanted to get some other opinions first. I know it's not electrical, like a capacitor or transistor. I believe it's a mechanical issue. Are these pots known to go bad?
 
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What you are describing is the classic symptoms of a bad speaker protect relay. The contacts get tarnished and don't make a good connection at low volume (low voltage drop across the contacts). Turning the volume up increases the voltage drop across the contact that has only partial connectivity, and breaks through to good connectivity, due to the higher voltage drop. Many of the relays can be opened , cleaned, and reinstalled (only if there is contact plating left). Others need to be replaced.
 
AE Bob said:
What you are describing is the classic symptoms of a bad speaker protect relay. The contacts get tarnished and don't make a good connection at low volume (low voltage drop across the contacts). Turning the volume up increases the voltage drop across the contact that has only partial connectivity, and breaks through to good connectivity, due to the higher voltage drop. Many of the relays can be opened , cleaned, and reinstalled (only if there is contact plating left). Others need to be replaced.
Click to expand...
I posted something similar to what you just said, then I stumbled upon this:

https://audiokarma.org/forums/index.php?threads/pioneer-sx-1010-relay-problem.912409/
 
AE Bob said:
What you are describing is the classic symptoms of a bad speaker protect relay. The contacts get tarnished and don't make a good connection at low volume (low voltage drop across the contacts). Turning the volume up increases the voltage drop across the contact that has only partial connectivity, and breaks through to good connectivity, due to the higher voltage drop. Many of the relays can be opened , cleaned, and reinstalled (only if there is contact plating left). Others need to be replaced.
Click to expand...
Hi, thank you for the reply! The Relay is brand new and was installed during the restoration. Do you still think this could be the problem?
 
kwayde said:
It says a new relay was installed so the relay may not be the problem.
Click to expand...
Yeah it's definitely not the problem. I also had another new relay installed since I made that forum post. It was installed in March of 2023 when the 1010 was professionally restored. Any other ideas of what it might be? My money is still on the volume pot, which I have one coming in.
 
Ben Rothman said:
Yeah it's definitely not the problem. I also had another new relay installed since I made that forum post. It was installed in March of 2023 when the 1010 was professionally restored. Any other ideas of what it might be? My money is still on the volume pot, which I have one coming in.
Click to expand...
See what the new pot will do before looking forward.
 
Though it may not be the relay the symptom is the same. I suspect a fouled connection somewhere; tape monitor, tone controls, etc. I know you said you cleaned them but I would investigate all of them when the sound drops out. Also take a look at the pre main jumpers, clean them and apply a film of D. Also I would do the standard switch left to right on the jumpers and see what happens, send the tape out to another unit monitor that signal, you will be able to narrow down your signal loss to a certain part of the unit that way.
 
Warren-Oates said:
Though it may not be the relay the symptom is the same. I suspect a fouled connection somewhere; tape monitor, tone controls, etc. I know you said you cleaned them but I would investigate all of them when the sound drops out. Also take a look at the pre main jumpers, clean them and apply a film of D. Also I would do the standard switch left to right on the jumpers and see what happens, send the tape out to another unit monitor that signal, you will be able to narrow down your signal loss to a certain part of the unit that way.
Click to expand...
That’s a great idea. I’ll go ahead and do that. The reason I’m still leaning towards the volume pot is the issue goes away right after I clean it. And when I clean it, I’m only cleaning the volume pot, and nothing else. Either way, it can’t hurt to have an extra original volume pot for the 1010 laying around. I think the jumpers being dirty could definitely be part of the issue. I’ll go ahead and clean those jumpers and report back. I’m a bit tied up with school currently so I’ll probably get to it around mid-next week.
 
Warren-Oates said:
Though it may not be the relay the symptom is the same. I suspect a fouled connection somewhere; tape monitor, tone controls, etc. I know you said you cleaned them but I would investigate all of them when the sound drops out. Also take a look at the pre main jumpers, clean them and apply a film of D. Also I would do the standard switch left to right on the jumpers and see what happens, send the tape out to another unit monitor that signal, you will be able to narrow down your signal loss to a certain part of the unit that way.
Click to expand...
I was advised to swap the channels by pulling the jumpers and using patch cords to swap the channels. I was told if the issue moved to the other speaker than it's dirty switch/volume pot issue, etc. If the channel doesn't move then it's much more of an electrical issue.
 
Does anyone have experience with dirty main in/pre out RCAs being dirty causing the issue I'm describing? I'd love to know if this is common
 
@markthefixer @zebulon1 Do either of you guys have some testing recommendations? I know you both are masters when it comes to these machines. The unit has been totally rebuilt and even has the updated power supply board installed. It's been running great for about a year. I do have a used volume pot on order. I am starting to wonder if cleaning the Main in/Pre out jacks would help. I have read that on a couple forums and I have never cleaned those jacks.
 
Its not some sinister problem.
If it was a PS or amp issue, it would be in protection.
New relay.
It’s probably poor contacts.
The signals go trough every switch and pot regardless of the switch position.
Think about it. 250mV line level signal has to plow its way through every 50 year old control.
Larry use to say (Probably still does) some Navy phrase about the 1010 having so many switches and toggles. I wish I could remember it.
The 1010 has push switches and toggles that can be taken apart, cleaned and lubed. Its the difference between a good restoration and a high quality restoration. Worth the time and effort.
When its acting up, look for channel signals at the in and outs of the switch board then the control amp. Volume is after most of the switching, so there’s lots of places it could stop before it sees the volume control.
The lower front chassis does unscrew from the sides. Makes access very comfortable.
Several threads on the cleaning process. I started a thread with a title sx-1010 rebuilders who care. I think there‘s images and a process.
 
I did find this thread, and this person seemed to have my exact problem. I'm starting to think the volume pot might be totally fine. When I play at ridiculously low volumes the left channel doesn't have any sound and when I move it a hair past that point which is still incredibly low on the volume range the left channel kicks in. I can then move the volume to that extremely extremely low spot where I previously had no left channel and it still works. This makes me doubt that it's volume pot. Either way, happy to have a back up. Does this seem
zebulon1 said:
Its not some sinister problem.
If it was a PS or amp issue, it would be in protection.
New relay.
It’s probably poor contacts.
The signals go trough every switch and pot regardless of the switch position.
Think about it. 250mV line level signal has to plow its way through every 50 year old control.
Larry use to say (Probably still does) some Navy phrase about the 1010 having so many switches and toggles. I wish I could remember it.
The 1010 has push switches and toggles that can be taken apart, cleaned and lubed. Its the difference between a good restoration and a high quality restoration. Worth the time and effort.
When its acting up, look for channel signals at the in and outs of the switch board then the control amp. Volume is after most of the switching, so there’s lots of places it could stop before it sees the volume control.
The lower front chassis does unscrew from the sides. Makes access very comfortable.
Several threads on the cleaning process. I started a thread with a title sx-1010 rebuilders who care. I think there‘s images and a process.
Click to expand...
Thank you so much for the reply. I can confidently say that I have cleaned the pots and switches correctly numerous times, and with the right products. Deoxit red for switches and Deoxit green for pots and faders. I am starting to suspect that it might be the Pre out/Main in jumpers and RCA jacks for those jumpers per this thread. https://audiokarma.org/forums/index...ubleshooting-my-sx-1010-right-channel.508931/. Have you seen this issue before? I cleaned the switches and pots about 5 separate times when this issue arose and it changed absolutely nothing.
 
zebulon1 said:
Its not some sinister problem.
If it was a PS or amp issue, it would be in protection.
New relay.
It’s probably poor contacts.
The signals go trough every switch and pot regardless of the switch position.
Think about it. 250mV line level signal has to plow its way through every 50 year old control.
Larry use to say (Probably still does) some Navy phrase about the 1010 having so many switches and toggles. I wish I could remember it.
The 1010 has push switches and toggles that can be taken apart, cleaned and lubed. Its the difference between a good restoration and a high quality restoration. Worth the time and effort.
When its acting up, look for channel signals at the in and outs of the switch board then the control amp. Volume is after most of the switching, so there’s lots of places it could stop before it sees the volume control.
The lower front chassis does unscrew from the sides. Makes access very comfortable.
Several threads on the cleaning process. I started a thread with a title sx-1010 rebuilders who care. I think there‘s images and a process.
Click to expand...
The switches and pots make absolutely no noise and operate as smooth as silk. I am happy to clean them again if that's most likely the problem. I have never cleaned the jumpers or the rca jacks where the jumpers go, and after reading that forum, I think that it could be part of the problem. Have you seen that before? Everything has been gone through on this unit. It has the new updated power supply board as well.
 
When the channels are dropped check the supply voltages on the control board.
There should be +-24 volts. Check the output for a signal. Use the Tuner, tuned to a station or a CD player through the AUX and your meter set to AC mV‘s, watch for the jumping signal.
Look for the signals right at the volume. Set the volume as you would when having the problem.
Move wires around and gently push on the boards. See if you can make a change and hear a channel.
(General troubleshooting after 1600 PST.)
Note:
Ive seen some really crusty contacts after I thought performed a thorough Deoxit treatment.
What happens is the crust is floating around and still causing trouble. Sliding contacts are tarnished beyond what the Deoxit can clean.
Look for signals and the correct voltages for the boards. Hopefully you can get close to the trouble shortly.
 
zebulon1 said:
When the channels are dropped check the supply voltages on the control board.
There should be +-24 volts. Check the output for a signal. Use the Tuner, tuned to a station or a CD player through the AUX and your meter set to AC mV‘s, watch for the jumping signal.
Look for the signals right at the volume. Set the volume as you would when having the problem.
(General troubleshooting after 1600 PST.)
Note:
Ive seen some really crusty contacts after I thought performed a thorough Deoxit treatment.
What happens is the crust is floating around and still causing trouble. Sliding contacts are tarnished beyond what the Deoxit can clean.
Look for signals and the correct voltages for the boards. Hopefully you can get close to the trouble shortly.
Click to expand...
Thank you for the advice! I'll try what you suggested and see if that solves the problem. I am still curious to see if you have seen the jumpers cause this type of problem? I find it interesting that the guy in this thread https://audiokarma.org/forums/index...ubleshooting-my-sx-1010-right-channel.508931/ had the exact same symptoms and chad already cleaned the pots and switches. Where do the jumpers lay in the signal path? I think that I should clean the jumpers as well as clean all of the switches again and see if that solves the problem I'm only leaning towards the jumpers as I have never cleaned them or the RCA jacks where they go. I am thankful that this isn't an electrical issue involving any capacitors and transistors. Any other advice/ideas would be amazing!
 
zebulon1 said:
When the channels are dropped check the supply voltages on the control board.
There should be +-24 volts. Check the output for a signal. Use the Tuner, tuned to a station or a CD player through the AUX and your meter set to AC mV‘s, watch for the jumping signal.
Look for the signals right at the volume. Set the volume as you would when having the problem.
Move wires around and gently push on the boards. See if you can make a change and hear a channel.
(General troubleshooting after 1600 PST.)
Note:
Ive seen some really crusty contacts after I thought performed a thorough Deoxit treatment.
What happens is the crust is floating around and still causing trouble. Sliding contacts are tarnished beyond what the Deoxit can clean.
Look for signals and the correct voltages for the boards. Hopefully you can get close to the trouble shortly.
Click to expand...
Side note, I couldn't find your thread "SX-1010 rebuilders who care." I tried searching via the search function and google. Could you paste a link?
 
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