I recently acquired a Pioneer SX-950. I opened it up to clean all the dust and pots. I was only able to access the volume and balance pots. DeOxit helped a lot to get all the scratchy sounds and intermittent audio issues fixed. I noticed my tuning meter wasn’t moving. I noticed when I jiggle the FM selector button the tuning meter would intermittently work. So I spayed a short burst through the front panel onto all the selector buttons and worked them in. I waited about two mins. Turned on. The tuning meter works great. But now I have zero audio. And a small pop when I turn off the unit. And help would be greatly appreciated.
Pioneer SX-950 newbie help.
- Thread starter Corpse
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Tape monitor was off. Haven’t tried headphones. No audio on any input. After I sprayed deOxit thru the front panel I worked the source buttons a bunch of times. Like you would with volume pots to clean the contact. I waited two mins. Turned it back on and nothing. After taking the faceplate off I noticed the deOxit likely did not make it to the inside of the unit from the little crack around the buttons that I was spraying into. I’m wondering if I pressed the buttons too hard or rapidly and screwed something up. The fm tuner shows stereo and the meters came to life. The meters weren’t working before I did this.
MegaHurts
Super Member
Are jumpers for pre-out are still in place?
Not sure what might have been covered in deoxit on the board by spraying blindly - it can get quite involved in order to properly access switch/pot contacts, where dismantling the whole front on some units is needed. Take this Nikko as an example - there is no other way I can see to properly access the slider contacts. Removing the bottom plate can provide better access sometimes on some units.
Hard to say what may have stopped the sound on yours if it was working previously from just excerising knobs/switches. Solder joints or the pots themselves?
Not sure what might have been covered in deoxit on the board by spraying blindly - it can get quite involved in order to properly access switch/pot contacts, where dismantling the whole front on some units is needed. Take this Nikko as an example - there is no other way I can see to properly access the slider contacts. Removing the bottom plate can provide better access sometimes on some units.
Hard to say what may have stopped the sound on yours if it was working previously from just excerising knobs/switches. Solder joints or the pots themselves?
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Yeah disassembly to that point in the picture is beyond my expertise. I’m fairly new to vintage stereos. All I really know how to do is clean the pots and doing light dusting/cleaning. Looking at mine, there is a board in the way of the board with the switch pots. Im not willing to mess something up further. I might need a professional to help me out.
MegaHurts
Super Member
Not trying to scare you off. If you do try to get further access to pots as you build confidence on working on vintage gear, take a lot of pictures before/during. I bag and label where screws go for the unit so they don't get lost and I don't forget. I'll often work on several at any given time while waiting for part oders or just taking a break from a unit that is being stubborn and not submitting to my will. Experience is gained by pushing forward. Best of luck whichever way you decide to proceed, and please update the thread with what the issue/fix was for others.
I would not spray any more stuff until you read some on how to properly use it. Also it makes a difference what caig product you use on which switches. That is very nice receiver, take care of it properly.
Thanks for the confidence boost. I did take the board off under the board I need to get to. But the board I need to get to the wires are too bunched and tight to flex the board so I can see what’s going on with it. I feel like I may pull a wire loose if I try to force it.
Thanks for the advice. I’m going to be a lot more careful with it in the future. I’m used to hosing down the pots on my tube guitar amps. I think i need to be a little more careful with this one.
I don’t think so but not 100%. Putting it back together now. I’ll update when I do
So I had everything taken apart as much as I could. I took the face plate off the two boards so that I can get all the pots. I was never able to get to the board that has the pushbutton switches. My tuning knob would not glide at all. It was actually pretty hard to turn. I disassembled that clean the old grease off the shaft re-lubricated it and put it back together, now it glides like it should. After reassembly I plugged everything in and everything came to life. I’m not sure what the problem was. Maybe it was the tape monitor. But I’m pretty sure it wasnt. the tuning meter and signal meter are both working perfectly now. Thanks for your suggestions and the boost of confidence.
Might have been a control position issue. There are two tape monitor loops and an adapter loop, any one of those three switches will override and kill all audio input except for what is fed through them. There is also an audio muting switch over by the volume knob which will knock the audio level down low (particularly handy when using a manual turntable). If you have low volume level issues in the future be sure to check that one, it’s not uncommon to mistake it for the power switch and flip it accidentally (I still do it from time to time after all these years lol!). You have a fantastic receiver there, take good care of it!
Awesome advice. I can see how in the heat of the moment when you realize something is wrong, how simple things can get overlooked. I’m glad it happened though. Otherwise I wouldn’t have taken the tuning knob apart to fix it. So I’d say it’s a blessing.
Well I just tried the AUX channel. I noticed the volume was about half of what it is on FM. I realized the left channel doesn’t output any audio when in AUX. if I turn the balance all the way left and crank the volume I can faintly hear pieces of the audio. Any suggestions on this? Could it be the rca terminals in the back?
This is the board to switch inputs. Fm am aux phono. I notice pin 11 doesn’t have a wire connected. I don’t see any loose wires.
MegaHurts
Super Member
You will want a service manual for the receiver to see boards, circuits, wiring...
It may be avail in the audiokarma database if you can't access downloads from hifiengine.
Edit:
I don't see the 950.
http://www.akdatabase.org/AKview/thumbnails.php?album=44&page=3
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