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Pioneer sx-424 low crackle/rumble

Wes K

Wes K

New Member
Hi everyone. Newb here looking to troubleshoot an issue on an old Pioneer receiver I picked up. It is a sx-424 model. When I first power it on there is a low crackling/rumbling sound, it almost sounds like wind coming through the speakers. It starts out constant then becomes more and more sporadic the longer the system stays on. It does not intensify when I adjust the volume, select inputs or use the tuner. It is, however, affected when I adjust the bass knob, and less noticeably on the treble knob. This sound occurs regardless of whether I use the original speaker plugs or the screw down adapters. When the sound goes away, I get great sound out of this receiver, so I'd like to fix it if I can. Any advice would be greatly appreciated. Thanks!
 
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You got'a Deox all the controls first. Switches and pots, everything that can move.
 
Yeah, I've just finished hitting all the pots and switches with Deox. No change. It does completely go away after the receiver warms up after 20-30 minutes. Could it possibly be in the speaker inputs? This model has the weird slots with screw down adapters (I have one set of those). The sound remains the same regardless of whether I hook the speakers up to the screw down adapters or directly into the slots. It also doesn't make a difference whether I use speaker inputs A or B.
 
Does it do it on AUX input? Q1-Q4 (2sc1344) on the AF unit board look suspect to me, but you say it goes away with use, which has me wondering.
 
Yes, it is constant on AM, FM, AUX or PHONO input. Same sound all over. But, I just noticed something different after the cleaning I just gave it. The sound is now only in the left channel. If I run 2 speakers through right channels on both A & B inputs, the sound is gone. If I hook a speaker up to a left channel (A or B inputs) the sound come back in the left channel.
 
Did the cleaning make the right channel better? Or you never noticed the static on the left channel only?
Sometimes more than one Deoxit application is needed.

2SC1344 can be sub'ed with a KSC1845 (512-KSC1845FTA)
2SC1318 can be sub'ed with a KSC2383 (512-KSC2383YTA)
2SA720 can be sub'ed with a KSA1015 (512-KSA1015YTA)
All equivalents are ECB

Are you wanting to get into the nuts and bolts? You got the tooling?
 
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