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Pioneer SX 880 Balance and bass/treble inconsistent vol

Discussion in 'Pioneer Audio' started by sdineen, Nov 24, 2018.

  1. sdineen

    sdineen New Member

    Messages:
    6
    Ugh. I have an old Pioneer SX 880 that is sick and
    • The speaker channels are out of sync volume wise and balance must be constantly adjusted in parallel.
    • The Left channel has WAY more bass the the right. Probably too a fault although the right can use a little more, sounds very dry. Actually with headphones only, more like all the mid went to the Left, and right is just heavier with bass??
    • VOL/Balance issue occurs whether speakers are in A or B
    • On headphones, I am currently having difficulty trying to determine if one channel is lower volume/balance (thanks 200+ rock concerts :-/) BUT definitely still hear the toneality issue when swinging to full right or left.
    • Assume preamp?
    What have I done so far?
    • Deoxit to the 9th degree.
    • Resoldered joints that seemed a little iffy.
    • confirmed all wired connections and caps/resistors by eye at least.

    Any help would be supper appreciated......
     

     

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  2. markthefixer

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

    Messages:
    21,110
    Location:
    Bensenville,Illinois
    Please expand upon the "deoxit to the 9th degree" - please name the deoxit points done.

    I have had people say things like that, and troubleshot it to an undeoxited set of contacts.
    If it goes in n out, up n down or roundy round - it needs deoxiting and lubing/protecting.

    Bad (drying out) caps can cause tonality issues. depends upon the circuits if it's a loss or a boost.
     
    sdineen likes this.
  3. rcs16

    rcs16 Super Member

    Messages:
    4,057
    Location:
    Baldwin, Ontario, Canada
    It is really hard to figure out channel level balance issues without accurate test equipment.
    You basically need to inject a signal into the L/R inputs and trace/measure the signals as they go thru switches, pot etc to figure out what is the culprit.
    You can also measure switch contact resistances with the unit powered off, using your ohmmeter, following the signal flow in the schematics.
    I know I am not much help to solving your issue but as Mark adds their could be any number of possible suspect parts.
     
    sdineen likes this.
  4. sdineen

    sdineen New Member

    Messages:
    6
    Thanks for the Reply! I can show pictures or post a video, but what I meant to convey is that I tried to deoxit first with CRC brand electrical contact cleaner, then with Deoxit 5, a few times in hopes this would be an easier fix. I sprayed in every switch in pot, every crevice or hole, and worked them feverishly. Even the power switch because... why not. On the caps, I did find a listing of some else's recapping work here http://www.audiokarma.org/forums/in...-need-some-advice.370783/page-4#post-5909763> so assume focus on Main board or anything in particular low hanging?
     
  5. sdineen

    sdineen New Member

    Messages:
    6
    Got it, and appreciate you telling it like it is so to speak. I may have to lean on an electrical engineer pal of mine for a little further guidance, but think if there is any low hanging CAP replacement guidance (low hanging for the right channels flat tone) I would appreciate it. The left is still a little too boomy/bassy in my opinion but I'll take that over the "AM car radio tonality" I'm getting off the right. :)
     
  6. rcs16

    rcs16 Super Member

    Messages:
    4,057
    Location:
    Baldwin, Ontario, Canada
    For a shot gun approach, seek sky blue coloured Sanyo ecaps and replace ASAP :)
    Won't help if it is a switch issue, take my advise and measure the switch contacts resistances, that way you know for sure if the switches are op properly.
    If you plan on fixing these units, you need to learn how to follow a schematic and locate the parts on the circuit boards, trace wire connections.
    You would be surprised what that DMM can do for you.
     
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  7. sdineen

    sdineen New Member

    Messages:
    6
    Sky blue....so they look like these, rcs16? (see at least one other real quick by eye on the tuner)
    [​IMG]
     
  8. EastPoint

    EastPoint Factory Code No. 4200 Subscriber

    Messages:
    4,662
    Location:
    Milwaukee, WI
    No, those are tantalum caps. Also a good idea to replace them.
     
  9. rcs16

    rcs16 Super Member

    Messages:
    4,057
    Location:
    Baldwin, Ontario, Canada
    Close :) but not those ones, I am not 100% sure if the Sanyo's are used in your unit
    Use Nichicon UKL series ecaps as a tantalum replacement since they have the lowest leakage current, comparable to tantalum
     
  10. EastPoint

    EastPoint Factory Code No. 4200 Subscriber

    Messages:
    4,662
    Location:
    Milwaukee, WI
    I don’t think the 880 has sky-blue caps but it should have some orange ones that are the same and go bad too.
     
  11. markthefixer

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

    Messages:
    21,110
    Location:
    Bensenville,Illinois
    No cssa sky blue sanyo's in the sx-880, but there's a BUNCH of itty bitty 1 to 10 uf can caps that can dry out (loose capacitance and then usually bass)
    - and the itty bitty ones dry out first.

    While the tone controls are passive, the IC's (q3,q4) preamp circuit might have a 'lytic in the feedback that then makes too much gain. or not enough gain...

    TRY THE STEREO / MONO mode switch in MONO and test how it affects each channel's sound.

    note: the volume and balance controls are AFTER the stereo/mono summing switch (it performs a L+R function ) so problems with the 0.22uf / 2.2 uf S6 low filter could be manifesting.
     

     

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  12. sdineen

    sdineen New Member

    Messages:
    6
    Thanks everyone for the input! Just to confirm, selecting MONO has no impact to either the sound level, or the tonality. One channel still lacking power and proper tone, regardless. Will look at replacing the 0.22uf / 2.2 uf S6 low filter.
     

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