1. Time for some upgrades in server hardware and software to enhance security and take AK to the next level. Please contribute what you can to sales@audiokarma.org at PayPal.com - Thanks from the AK Team
    Dismiss Notice

Pioneer SX-850 Snap, Crackle and Pop

Discussion in 'Pioneer Audio' started by joe4fun, Jul 5, 2011.

  1. joe4fun

    joe4fun Stereophilus Maximus

    Messages:
    48
    Location:
    Bay Area, California
    Hi Guys.
    I have a Pioneer SX-850 Receiver that I am rarely using. I went to power it on this weekend, and it played for a minute (FM) and then I started hearing these popping and crackling noises through the speakers. I powered it off, and tried turning the volume all the way down, same popping. I switched from FM to CD, and there was nothing for a few seconds, but then more popping. I just bought an amp and tuner, so I am going to swap out the pioneer out of the workshop into the house where I can take it apart and inspect the insides.

    I am very light in the technical department. Anyone have experience with this symptom? I hate to have to get rid of it. There are not that many vintage repair shops around anymore.

    Thoughts?
    Thanks
    Joe4fun
     

     

    Please register to disable this ad.

  2. Watthour

    Watthour Electron Rancher - JS3600

    Without diagnosis, a WAG would be that you have a cap(s) in the unit starting to fail. In the limited number that I have been in, transistors getting noisy from breakdown typically produce a more constant and lower level "hiss" noise rather than sharp, higher amplitude pops and snaps.
     
  3. mattsd

    mattsd AK Subscriber Subscriber

    Messages:
    1,647
    Location:
    Cincinnati, Ohio
    I would have to say bad transistors. The 2sa725's and 726's on the EQ amp, flat amp and power amp boards are the ones, there is a total of 8. Replacement is from Mouser, 512-KSA992FBU.

    Power Amp:

    AWH-059: Q1: 2SA726: 512-KSA992FBU
    AWH-059: Q2: 2SA726: 512-KSA992FBU
    AWH-059: Q3: 2SA726: 512-KSA992FBU
    AWH-059: Q4: 2SA726: 512-KSA992FBU

    EQ Amp:

    AWF-011: Q1: 2SA725: 512-KSA992FBU
    AWF-011: Q2: 2SA725: 512-KSA992FBU

    Flat Amp:

    AWG-038: Q5: 2SA725: 512-KSA992FBU
    AWG-038: Q6: 2SA725: 512-KSA992FBU
     
    slimecity likes this.
  4. markthefixer

    markthefixer On Hiatus, dealing with Dad's estate full time Subscriber

    Messages:
    21,124
    Location:
    Bensenville,Illinois
    I'm just going to pop in here,

    First, good analysis Matt

    Second, we need to be sure it is BOTH channels popping (at the same time?).

    The reason is that the power amps on this one run on + and - 51.5v but also on +35v to the input (differential) section.

    If the 35v regulator has become noisy prior to failing (failing would drop out the protection relay) it would be injecting noise all over the system.

    So, the safest thing to do is to also replace
    AWR-101 Q7 2sc1318 512-KSC2690AYS to-126 ecb 120/a160 1.2a 20w 155mhz 35-320hfe $0.40

    It IS a larger cased device, which will run MUCH cooler than the original design (this position is notorious for heat failures), but you may need to enlarge the holes in the pcb slightly.


    as an added complication, with some of the 725/726's failing they will put their shot noise back onto the +35v power supply line where it will come out ** everywhere **. Thus.. do them all...
     
  5. mattsd

    mattsd AK Subscriber Subscriber

    Messages:
    1,647
    Location:
    Cincinnati, Ohio
    Good catch there, Mark, I had forgotten about the regulator (which is pretty bad, considering I just did that upgrade along with a recap to a SX-950 with the same problem).
     
    Last edited: Jul 6, 2011
  6. joe4fun

    joe4fun Stereophilus Maximus

    Messages:
    48
    Location:
    Bay Area, California
    Mark and Matt: The noises were definitely from the left channel. These things can be frustrating. Today, I turned it on and it played. But frankly, I don't trust the unit now after hearing tha noise the other day. I don't really think I flipped any switches to make it play properly. This unit plays in my workshop with no AC and it was 100 degrees give or take this weekend. I believe there is a problem, but now its going to be one of the intermittent variety. Any further ideas? I am going to look online for a local shop. If I were lucky enough to find one, I could have it cleaned and gone through, and have all those transistors replaced as per the comments- You guys are very good, and its very appreciated.

    joe
     

     

    Please register to disable this ad.

  7. mattsd

    mattsd AK Subscriber Subscriber

    Messages:
    1,647
    Location:
    Cincinnati, Ohio
    We will go farther if replacing the transistors and cleaning the controls doesn't fix the problem, but I would be willing to bet those two things will fix it. Since the problem is in the left channel only, it is probably the 2sa725's and 726's that are the problem, but the regulator should be replaced as well for preventative maintenance.

    Post where are you, there are a lot of people on here that could make a recommendation for tech based on where you are.
     
    Last edited: Jul 6, 2011
  8. joe4fun

    joe4fun Stereophilus Maximus

    Messages:
    48
    Location:
    Bay Area, California
    Matt:
    I am in the San Francisco Bay Area. Is that a Sansui G-9000 I see there in your signature line? I have been looking, but a lot of places are either already out of business or no longer do repairs on vintage equipment...

    joe4fun
     
  9. Uncle Bambi

    Uncle Bambi Funky Tut

    Messages:
    1,920
    Location:
    San Ramon, CA
    If you're anywhere close to Dublin, I HIGHLY recommend The Stereo Doctor in Dublin, CA. Steve is the owner and primary tech, and he will take care of you. He was a Pioneer certified repair center during the Silver Series era, and knows them inside and out.

    Of course - if you'd rather not spend money on it, I've always wanted an 850.......... :D
     
    Last edited: Jul 12, 2011
  10. joe4fun

    joe4fun Stereophilus Maximus

    Messages:
    48
    Location:
    Bay Area, California
    Uncle Bambi,
    I am in Oakley, which is on the Sacramento delta near Walnut Creek.
    Dublin is easily reachable, and I really appreciate the tip on the Stereo Doctor. I will have to look them up on the web- If they sell anything, its always cool to look around as well.

    I have thought about taking my units in for service, but up to now have not seen anyone reputable.

    Much appreciated.:thmbsp:

    joe4fun
     
  11. Uncle Bambi

    Uncle Bambi Funky Tut

    Messages:
    1,920
    Location:
    San Ramon, CA
    No problem at all. I've had good success fixing some Pioneer receivers, and when I've got myself in a jam Steve has been free with advice and very helpful in fixing my screw-ups when needed. He knows his trade.

    And yes - he does have some reconditioned gear for sale in is small store front. I picked up a very nice pair of Advent 3002's from him just recently.

    The web site isn't much, but it'll get you in contact:
    http://www.stereodoctor.com/
     

     

    Please register to disable this ad.

  12. joe4fun

    joe4fun Stereophilus Maximus

    Messages:
    48
    Location:
    Bay Area, California
    Uncle Bambi
    I had a brief email conversation with Steve and explained the problem, he also brought up aligning the tuner which goes with his service of going through the unit and testing, replacing what is not up to specs. The price is a tad steep at 200 plus, so I may have to wait a little.

    I looked at his site, which is mostly good to get the phone, address and read his "story". I will be dropping in there eventually.

    Thanks again.

    joe4fun
     
  13. mattsd

    mattsd AK Subscriber Subscriber

    Messages:
    1,647
    Location:
    Cincinnati, Ohio
    I'm glad you found a good tech, let us know how the repair goes when you get there.

    No, it's is the smaller brother to it, the G-8000, it was my best score and find to date. The faceplate was as brown as the wood case when I got it, but as you can see, it cleaned up very nicely. I have a blog with more detailed photos if you would like to see it better.
     
  14. Juicer

    Juicer New Member

    Messages:
    18
    Hello ALL!! First let me say " THANK YOU " to all that made comments and gave advise - this is a wonderful site. I know this is an old posting but I wanted to add my comments as my recently EXELLENT CONDITION LISTED auction site purchased SX-850 was expericening the same issues as mentioned - FROM DAY ONE - crackling - popping - low level noise with the volume turned all the way down on all functions. Occuring quite often every time I turned it on. Figured I give a recap a try so I ordered all the parts from Mouser - they should be here in a couple days I would think. To get a jump start I disassembled the receiver removing the flat amp and tone amp boards and cleaned / lubed all the pots and switches. I also spotted some solder joints on both boards that looked questionable so I resoldered them as well. I also cleaned and lubed the power switch, as it seemed cushiony and not snappy like the other switches. After cleaning it I stood it on its side and connected speakers, and an antenna and powered it on to assure everything was still functioning. I left it on and let it play on a pai of Radio Shack Opimus Minis while I did some other things - listening for issues - NOT one pop - NO crackling - NO hum - NO noise - put it all back together and took it back upstairs. Hooked up the Technics SL 1700 and played the entire Eagles " The Long Run " ablum cranking it up on the JBL L100s & Bose 301s ( Bose haters refrain) - not one issue at all - and what an awesome sounding receiver. I will now file the parts and do the recap when I start to have issues, but for now I am going to enjoy my new purchase. So, my fix was cleaning the pots and switches and ??? maybe the solder joints ??? Hopefully this post does not JINX me - LOL again, thanks to everyone who took time to post their thoughts.
     
  15. Juicer

    Juicer New Member

    Messages:
    18
    Well spoke too soon ... popping and cracking is back :(
     
  16. Bob

    Bob AK Subscriber Subscriber

    Messages:
    2,386
    Location:
    West coast
    its 40 YO - needs a recap and follow the advice of the AK giants (above), don't cheap out,
    $200 is cheap and if that's all that it takes then it's $5/ year for the next 40.

    keep these out of the landfills, city dumps, and the flippers.
     

     

    Please register to disable this ad.

  17. EastPoint

    EastPoint Factory Code No. 4200 Subscriber

    Messages:
    4,669
    Location:
    Milwaukee, WI
    It’s probably an amp board transistor. Shotgun that board and go from there. If you want to figure out which one it is, just use freeze spray to pin down the bad one.
     
    slimecity likes this.
  18. slimecity

    slimecity Super Member

    Messages:
    3,079
    Location:
    New Zealand
    While i agree this is most likely a small transistor going in the flat amp - you want to narrow this issue down by isolating the respective stages in the amp (pre & power).

    So - remove the jumpers at the RCAs at the back (pre out / power or main in) - run a set of RCA leads out from the pre out RCA jacks into any input on another amplifier - running a music signal into the Pioneer - is the issue still there?

    Then, run an ipod/iphone (set with the volume SET TO ZERO for starters) directly into the main in RCA jacks - this runs straight in to your poweramp - the volume control on the pioneer will not work if you do this - very carefully turn the volume up on your music source. is the issue still there?
     
  19. pjf610

    pjf610 Active Member

    Messages:
    207
    Hi all, In reading thread #4 you can change out a semi (TO-92 to a TO-126?? package)
     
  20. QSilver

    QSilver Super Member

    Messages:
    1,201
    Of course you can :thumbsup:
     

Share This Page