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Access to SX-3900 Pots and Switches to deoxit

Discussion in 'Pioneer Audio' started by lastvr, Jul 14, 2013.

  1. lastvr

    lastvr New Member

    Messages:
    3
    :scratch2: Should I unscrew the black sub-plate under the faceplate in a SX-3900 where the pots and most of the switches are attached to access them and deoxit them?

    Will I be able to separate this black sub-plate enough from the main unit to do the work with all those switches, pots and wires that are attached to it without endangering the unit?

    Should I disconnect anything before separating the sub-plate a little from the main unit so nothing gets damaged/broken?

    I had never opened a receiver in my life, was good with basic car mechanics back in the day but never delved into electronics apart from installing a CD Receiver in a car by myself and soldering a few wires in the process.

    Thanks for any help in advance, you guys have a great forum going on here!
     
  2. markthefixer

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

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    Location:
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    oh, man... this is not an easy answer and then the display board and power supply and the push button rods (find straws to help locate them for reassembly) make things even worse.

    there are a LOT of motion transfer cables that move the switches elsewhere too (the blue ribbons).

    Start looking around for sx-3900 threads in here, for dis-assembly pictures that I can help explain - trying to (get me to) do it flat footed (i.e. no pictures or room to open one up) is just asking for disaster.
     
  3. lastvr

    lastvr New Member

    Messages:
    3
    I had found restoration pictures in this forum shared by Brent W. in 2008:

    http://share.shutterfly.com/share/r...ex=16&sid=0QbtG7lw1csXsQ&fid=08db185f6b2bef66

    I noticed after I posted the question that the pots and many of the switches that are screwed to the sub-plate are attached to electronic boards (pics 15 and 16). So it figures I will have to take the pots hexagonal nuts off, and unscrew the switches that are screwed to the black sub-plate off.

    Is that so, or could I leave some of the switches (i.e.: the ones with transfer cables) that are not attached to electronic boards screwed on to the sub-plate in order to separate it a little bit from the main unit and deoxit?

    From what I see, unscrewing everything from the sub-plate will perhaps mean that I won't have a way of putting it all back together again unless all the front of the unit is disassembled and assembled again.

    With the sub-plate in place and without unscrewing anything, I have enough access to deoxit the balance pot and the adaptor switch (the worst two), plus the tape duplicate and tape monitor switches.
     
  4. SolutionRoom

    SolutionRoom ...***...

    Messages:
    661
    Location:
    Orange County, CA
    There are a lot of parts attached to other parts when removing the faceplate and inner (black) plate. But if you are meticulous and keep your screws and such separated well and use a digital camera to take photos as you go, you should have no problem. The manual "might" help you with the exploded views too, IF you get in a pinch. It's not that complex really. Just a lot to do and will take some time. The Mechanical part of this receiver isn't too tough... it's when you get into the weeds on the electronics that it gets deep. You ARE in good hands here though, with MTF.

    One "trick" to use might be to lay out all your parts where they came off of to the side on a nice clean surface. That way you can just see where they came off of when re-assembling it. Just do a THOROUGH deoxiting when it's apart, so you need not repeat the process.
     
  5. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

    Messages:
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    Location:
    Glen Burnie Md.
    Take 2 straws from DeOxit/Faderlube or whatever that is the same size. Heatshrink them together. Then take a piece of wire that is smaller than the inside of the straw and insert it about 1-1/2". Hook the end of the wire so it doesn't fall inside.

    BEND THE STRAW to just past 90* (the end with the wire in it) and warm it up with a hair dryer so it will set in this position (about 1/4" to 3/8"). Let it cool down in this position. The wire prevents kinking of the inside of the straw. Remove the piece of wire.

    Now you have a long enough straw that will shoot DeOxit straight INTO the slot/hole of the pot/switch pretty much anywhere on the unit WITHOUT disassembly.

    Thanks to MARKTHEFIXER for the original idea.

    Larry
     
  6. markthefixer

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

    Messages:
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    Location:
    Bensenville,Illinois
    your main non- rotational control static problems will be found in the motion transferred switches UNDER the mezzanine switching board. Follow the blue cables - and sorry, it's a pita to get to...

    do you use the tape monitor loops?
     
  7. lastvr

    lastvr New Member

    Messages:
    3
    Thanks for your responses. I'm waiting for a deoxit kit I ordered by mail to be delivered and I'll take it from there, deoxit what I can and test and deoxit some more, etc. I set up a large table in the basement padded with scrap rug panels just for that. I'll do it in my spare time methodically and slowly, with no time limits, a little bit at a time in order to avoid disaster (I've never done anything like this).

    I don't use the tape monitor loops. My main use for now would be the auxiliary input in order to stream music from the internet with a laptop. In the future I would like to get a fine turntable and use it with an old LP Records collection I have in storage. I have a Pioneer SX-737 and a Sherwood S-7225 bought for little money in Tag Sales. They work fine except for the AM radio on the Sherwood which is completely silent (insignificant).

    If I get a hold of disassembly pictures I will post the link or the pictures. I am taking pictures myself and might be posting some in the future after I learn how to post them.
     
  8. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

    Messages:
    19,334
    Location:
    Glen Burnie Md.
    Service Manual with some dissassembly drawings HERE.
     
  9. markthefixer

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

    Messages:
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    Location:
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    posting pictures:

    hit Go Advanced

    at the bottom hit Manage Attachments

    notice the table near the bottom, the .jpg file should be
    less than 244.1 KB with a sixe smaller than 900 x 900

    hit Browse, first one in list

    will allow you to browse through your computer for the file.

    when you find it, hit Open

    the box will have the file name(s)

    hit Upload, after it's uploaded, then hit Close This Window

    Then hit Submit Reply after you are done typing.

    a thumbnail will now show at the bottom of the post, clicking on the thumbnail will give a larger version.

    lesson two, after you have attached thumbnails, will be on how to get thumbnails, and photo's from hosting sites, onto the post in large size.

    compared to wht you want to do on a 3900, this is easy.

    as far as the 3900, take copious notes, make drawings, take pictures, use small bags or containers to keep various groups of screws together. practice putting back together what you just took apart, before going deeper. it REALLY is different to the brain to reassemble, it has to do with learning rather than "thinking" about it. This applies to wreck scuba diving, cave scuba diving, walking through the woods (BTDT, found out the hard way the first time), you name it...
     
    Last edited: Jul 20, 2013
  10. mquinn25

    mquinn25 New Member

    Messages:
    12
    The SX-3900 is really a stinker to take apart. I have been putting this off for years now, but I just purchased an Onkyo TX 7000 as a temporary replacement for the Pioneer so I can take my time. (I actually like the Onkyo a lot!). My reason for disassembly is to inspect, clean, clean pots and switches and replace lamps. That black mounting plate behind the faceplate is problematic to say the least. I have been turning the unit side to side, front to back to see what the best solution will be. I inadvertently laid the chassis on a lamp base, crushing it of course, so now I need to find a suitable replacement for that.... o_O ... always something. Right now I have separated the Flouroscan/Dial section from the chassis, but it is still to difficult to work in there. I am going to have to mess with the tuner cord, it makes me really nervous, though.
     

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  11. markthefixer

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

    Messages:
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    Location:
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    re - Lamp base crushed: is this what fits into the acrylic light "diffuser" or "light pipe" holding the lamp?

    There is a silicon "rubber" lamp socket from Mouser. We have parts numbers and pictures in a thread that I cannot currently find.
     
  12. mquinn25

    mquinn25 New Member

    Messages:
    12

    Yes mark...exactly...it's the little wedge lamp socket that fits into the light diffuser bar (which is safely stored off of the work table). :) Thanks for this...I will look for it. I want to replace all three because they at EXTREMELY brittle after all these years.
     
  13. markthefixer

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

    Messages:
    20,537
    Location:
    Bensenville,Illinois
  14. mquinn25

    mquinn25 New Member

    Messages:
    12
    Mark....I can't think you enough for this. I just ordered (6) as I wanted a set for a future project. I know I want more Pioneer equipment. Not only do they sound great and look great, but I have a serious emotional attachment to them. I just need to get into those pots and switches and get this sucker back up and running. It looks really great inside, so I am not going to recap it or anything...just clean clean clean and replace the lamps...I'll post some pics once I get into it a bit more.

    Mike
     

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