Pioneer SX-580 Multiple Issues!!!

[tonythetech]

Hi all,

I recently picked up a Pioneer SX-580 and it came in rough condition but, still worked! Upon further digging, most of the capacitors where shot and the FM tuner potion would not pick up any stations, even with a antenna attached. The only time the FM worked is when it was in mono FM muting. AM works great, the AUX works great. So I decided to replace all the capacitors in the unit to start. I ended up with 2 major problems I cannot figure out.

1. The FM still does not work. The meter barely moves when I'm looking for a station. The stereo light never comes on either. Now, I have checked into the stereo muting button. When on the AUX source, it can switch to mono or stereo with no problem. So the button must not be the issue?

2. The Phono source.... the right channel goes crazy and is distorted when on phono. Even if you unplug the turntable and turn up the volume, the right channel freaks out and and is probably destroying my speaker. the meters go crazy too. Where do I even start to troubleshoot this?

Please, any help will help!

 

[Robisme]

Replace the transistors on the phono EQ board. Probably are 2SA725 and 2SC1919.

For the tuner, sounds like it needs an alignment.

Rob

 

[tonythetech]

Replace the transistors on the phono EQ board. Probably are 2SA725 and 2SC1919.

For the tuner, sounds like it needs an alignment.

Rob

I finally replaced accouple transistors like you mentioned! I replaced all the ones in the phono section and a couple known "trouble makers" from what I have been reading.
Below is a list on all the transistors in my Pioneer SX-580 (pretty sure I didn't miss any!):

Original - Quantity# - What was used/could be used - Did I replace?
2sa725p - 2 - KSA992FBU - YES
2sa726s - 2 - KSA992FBU - YES
2sa733 - 1 - KSA733G - NO
2sa798 - 2 - 2 _ KSA992Fs(bonded together for heat transfer) - NO
2sc1384 - 1 - KSC2690AYS - YES
2sc1438 - 2 - KSC22316Y - NO
2sc1919 - 2 - KSC1845FTA - YES
2sc461 - 3 - KSD1616 - NO
2sc535 - 2 - ? - NO
2sc945a - 1 - KSC2383 - NO
2sd712 - 1 - KSC2073TU - YES
2sk117 - 2 - ? - NO
3sk59 - 2 - ? - NO

After replacing the transistors, the AM, FM, and AUX sound amazing and there is no distortion or humming! But, sadly, I did not solve the issue of the right speaker having distortion only on PHONO. The distortion only comes through when the volume hits about 40% turned up. At low levels, it sounds okay with little - to - no distortion.

Also, I still cant figure out the FM issue of having no Stereo stations come in. I do not have access to a oscilloscope. With that being said, is there any way to "tune" or fix my FM?

Last thing, If anyone wants, I can can make a complete list of capacitors used/replaced in my 580.

 

[Bruno Primas]

A little reading for ya'..

https://audiokarma.org/forums/index.php?threads/how-to-clean-a-tuner-analog.144163/

 

[tonythetech]

UPDATE:

I have cleaned the crap out of the tuner section but still no results... I really think it needs a proper tune and I do not have the equipment to do that. If anyone knows anyone in the Pittsburgh region, that would be great!

Also, I am totally lost on the fact that now both speakers have distortion only in the phono.... I have replaced transistors, caps, and re-soldered a lot of the points. With little results.... Honestly, what do I do now? I attached the schematics for the phono section.

 

[Bruno Primas]

Are you using a tt with a built-in preamp? If you are, it needs to be off.

 

[tonythetech]

I wish it was that easy. The tt I have is a Marantz 6350. I also tried with no tt hooked up to it and I still get distortion on the phono.

 

[sruchris]

Do you have an antenna connected? Stereo will only kick in when you have strong reception. Trying moving the receiver to another part of you house, possibly closer to a window and away from any other devices that can cause interference.

 

[tonythetech]

Do you have an antenna connected? Stereo will only kick in when you have strong reception. Trying moving the receiver to another part of you house, possibly closer to a window and away from any other devices that can cause interference.

I have a T - 300 ohm connected to it. The location is probably not the issue. I actually had another receiver there that used the same antenna. I sold my old one to buy this Pioneer. The old receiver had no issue and would pick up a lot of stations in the same spot the pioneer is in.

 

[Bruno Primas]

I wish it was that easy. The tt I have is a Marantz 6350. I also tried with no tt hooked up to it and I still get distortion on the phono.

If it was working before you started replacing components, then it's a good bet some component value is wrong, put in the wrong way, or there's a solder bridge or lack of solder on the board.

One tip on the 580...You can tip it on it's side, unplugged, replace a component, then power it on, (still on it's side), and make sure nothing changed for the worse.

A dim bulb tester is also a good idea.

 

[tonythetech]

If it was working before you started replacing components, then it's a good bet some component value is wrong, put in the wrong way, or there's a solder bridge or lack of solder on the board.

One tip on the 580...You can tip it on it's side, unplugged, replace a component, then power it on, (still on it's side), and make sure nothing changed for the worse.

A dim bulb tester is also a good idea.

I am going to have to look into a dim bulb tester! thanks for that.

Now, I do know you can work on it on its side. That's actually how I have been working on and testing it! So, the issues were always there (That's how I got the unit cheap). I really thought buy changing out the caps, this unit would come back to life... and it did! the AUX works perfectly and sounds great. The AM works and comes in clearly. But, I bought the unit thinking I could fix the known issues (in over my head)

I have the service manual, do I start going point to point and testing components? I hate to keep throwing parts at it.

 

[sruchris]

Is there a De-Emphasis switch on the back of a SX-580? If so, try cleaning it.

 

[tonythetech]

Is there a De-Emphasis switch on the back of a SX-580? If so, try cleaning it.

There is! I will look into that! Could I cut that part out entirely? And jump the 75us.

 

[sruchris]

On a SX-580, does the FM Muting button also switch the mode to Mono? If so, you'll want to make sure FM muting is on.

 

[tonythetech]

On a SX-580, does the FM Muting button also switch the mode to Mono? If so, you'll want to make sure FM muting is on.

It does have FM muting but that puts the system into mono. Shouldn't some FM stations be in stereo?

 

[sruchris]

It does have FM muting but that puts the system into mono. Shouldn't some FM stations be in stereo?

I believe when FM Muting is on, stations will be in stereo. When FM Muting is off, stations will be in mono. Read the manual to be sure. I could be wrong.

 

[tonythetech]

I believe when FM Muting is on, stations will be in stereo. When FM Muting is off, stations will be in mono. Read the manual to be sure. I could be wrong.

This is straight from the manual:

"MODE/FM MUTING SWITCH

This switch is a combination of the FM muting switch and

The mode select switch. When the button is left under pressed (ON position) the reproduction is in STEREO mode, while the FM muting function acts to suppress unpleasant interstation noise while tuning between FM stations when listening to FM broadcasting. When the button is depressed (OFF position), however, reproduction is in MONO mode, while the FM muting function does not act, thus enabling suitable reception of weak radio stations when tuning in to the FM broadcasting station.

NOTE:

Recording stereophonically with the mode select switch (MODE/FM MUTE) in the MONO position may cause deterioration in channel separation."

 

[tonythetech]

Another Update:

I Figured out the distortion in the phono section!!! So, I will be the bigger person and admit it was two 3.3uf caps that were in backwards... The weird part is that this receiver always had that issue from the old owner. When I replaced all the caps, I was very cautious in taking out the old caps and replacing them in the same way they came out. I only came to this realization after double checking my work and seeing that two caps looked backward according to the board markings. so i double checked all my work and everything else looks fine! So, i want to thank everyone for the help on this issue.

One issue left!!!
The FM Stereo issue is still there. After checking on the De-Emphasis switch, I noticed it was in bad shape. I figured I will never use this function so I jumped the 75uf position and that made things better. I get NPR and oldie stations now and way clearer. But still no stereo stations. In fact, I have never seem the red LED come on for stereo. Also, the FM meter is not really accurate. Never was. For example, when I find a NPR station, I can tune it by listening and I will get it in very clear. But the FM meter will be showing little signal strength. Any guesses???

 

[jbh3]

I know this is an old thread, and I don't have much to contribute, but...

I have an sx-580 and bose 201 speakers and a technics turntable, that I bought in the 8th grade. Pretty much kept it going for the last 40 years, to play albums. A few years ago the left channel cut out, had to go mono for LPs, which sux. I moved the turntable out to my newer home theater setup and shelved the sx-580. FM also only plays on 1 channel. Today I tried the AUX for the first time, and stereo works! I'm using it for audio on my home PC, with the bose speakers.

If I recall, I had narrowed the problem down to the am/fm/phono/aux switch, and the repair was beyond my skills. I considered bringing it to a shop, but he wanted me to sign off on $300, so being a cheapskate I said no. I did de-oxy and QD electronics clean all the switches to no avail.. but maybe something did get fixed. Who knows. The sound from the Pioneer SX-580 / Bose 201's is pretty nice, and the Pioneer 80's look is cool in my high tech office:

 

[jpreza]

Another Update:

I Figured out the distortion in the phono section!!! So, I will be the bigger person and admit it was two 3.3uf caps that were in backwards... The weird part is that this receiver always had that issue from the old owner. When I replaced all the caps, I was very cautious in taking out the old caps and replacing them in the same way they came out. I only came to this realization after double checking my work and seeing that two caps looked backward according to the board markings. so i double checked all my work and everything else looks fine! So, i want to thank everyone for the help on this issue.

One issue left!!!
The FM Stereo issue is still there. After checking on the De-Emphasis switch, I noticed it was in bad shape. I figured I will never use this function so I jumped the 75uf position and that made things better. I get NPR and oldie stations now and way clearer. But still no stereo stations. In fact, I have never seem the red LED come on for stereo. Also, the FM meter is not really accurate. Never was. For example, when I find a NPR station, I can tune it by listening and I will get it in very clear. But the FM meter will be showing little signal strength. Any guesses???

Most likely it's the stereo separation. The SX-580 service manual has instructions on how to adjust the FM sensitivity.

Also, were the 3.3uF caps electrolytic? Usually these will take current pretty quickly and "explode" if installed backwards. Hopefully you were able to fix your amp.