SX-9000 My next project

Discussion in 'Pioneer Audio' started by patra710, Nov 10, 2017.

  1. patra710

    patra710 Active Member

    Messages:
    188
    Location:
    Beecher, IL
    I pick this up at an auction the other day for $35. The front was in good but the wood cast was rough.
    pioneer sx9000-2 006.JPG
    I took the cover off and there was 47 years of dust in it. I blew out the dust and clean the pots. I check the DC offset at the speakers outputs and had about 700mV. A bit high but I hook up some junk speakers and it did play. I was a little lost at first till I seen that there was two volume controls, one was a master volume and the other a source volume. First time I seen that. And I got no FM stereo light but I found help on this in the forum here.
    pioneer sx9000-2 009.JPG
    I like the tone color control it has, it did make a little different but I expect more after a recap. The reverb didn't seem to do anything. the output transistors, one channel has the stock 2SD218 in it, the other channel has SK9237 in it. I took some Windex, an acid brush and a shop vac and got the boards on the top side clean.
    pioneer sx9000-2 010.JPG
    There is around 20 2SC458 transistors in this stereo that I am planning to replace with KSC1845FTA. I am also thinking about changing out the output transistors with MJ21194G. I don't like the idea of two different brands of output transistors. And I have to pull them out to anyway put fresh grease on them. I can't see the main amp board and I am wondering why someone replace those transistors.
    I am starting to put together a parts list for this stereo. Does anyone knows of any other known problems with this stereo?
    Thanks
     
  2. blhagstrom

    blhagstrom Mad Scientist, fixer. Subscriber

    Messages:
    12,420
    Location:
    Duvall, Washington
    The reason you see high DC on the speaker terminals is because that is a cap coupled amp.

    That makes it sound different.

    TOTL cap coupled Pioneer receiver. The best.

    There are other problem transistors in there. 2SC1813? I forget. Bunch of them in the reverb board and I think the preamp or head amp board. Change those too.

    There are a billion e-caps.

    Once updated it’s going to floor you how good it sounds.
     
  3. patra710

    patra710 Active Member

    Messages:
    188
    Location:
    Beecher, IL
    Thanks, I have done other Pioneers and I was happy with the results. I put together a list of the transistors from the service manual but still need to compare them with what is really in it. Not all of the caps match the service manual, mostly just a higher voltage. I counted 15 boards in this Pioneer so I got my work ahead of me.
    When I got this Pioneer at the auction, there was a silver face Sony that was missing knobs and was only rated at 15 WPC. But someone paid more for it and pass by this Pioneer.
     
  4. blhagstrom

    blhagstrom Mad Scientist, fixer. Subscriber

    Messages:
    12,420
    Location:
    Duvall, Washington
    The SX-9000 is a sleeper but those damn transistors get noisy.
    Every one I've had or seen was noisy.
    I've had 2-3, worked on 1-2. Still have a couple more.

    The transistors in the reverb can cause noise even when you have the audio off to the reverb.

    Restoring those is just as much changing the small transistors as it is changing the e-caps.
    If fact, fixing the noise is changing the transistors and there is no reason to not change e-caps while fixing except the owner is cheap.

    Oh, fixing the function lamps is a joy too.
    They used lamp cartridge type housings.
    Since the cartridge is obsolete, you need to carefully take the cartridge out
    , then open it and then put a new leaded lamp in, then put it all back together. About an hour time each!

    Owning a great SX-9000 is either a very expensive labor cost or a true gift from a friend who will restore it cheap.

    Since so few properly restored ones exist, they probably never will get the value they deserve.
     
  5. patra710

    patra710 Active Member

    Messages:
    188
    Location:
    Beecher, IL
    Thanks again. I did some basic test, I put a square wave in and scope it at the pre-out. The square wave was not to square and the right channel was much stronger then the left channel. Putting a sine wave in and measuring at the pre-outs I got 371 mV AC and 491 mV AC where I expected 500 mV. There are still some switches that I couldn't clean until I take the front off but I don't expect much of a different. I check the output of the main amp with 8 ohm dummy loads and measure 22 V, about 55 watts on the right channel and 16.7 V, about 35 watts on the left channel. I did expect the left to be weaker because of the weaker signal from the pre-amp.
    As far as the value goes, I just enjoy working on these things. I am retired and it fills my time. I will sell it in the end and I will make some money on it but no where near what I should. But then I will find another and start all over again.
     
  6. blhagstrom

    blhagstrom Mad Scientist, fixer. Subscriber

    Messages:
    12,420
    Location:
    Duvall, Washington
    They are a labor of love.
    TOTL can be a challenge to work on with all the extra features.
     
  7. cwh

    cwh AK Subscriber Subscriber

    Messages:
    371
    Location:
    Oakland, Ca.
    Cool project. I look forward to seeing more pics of the restoration.
     
  8. patra710

    patra710 Active Member

    Messages:
    188
    Location:
    Beecher, IL
    I got my parts in, so I am hoping to start this project this weekend. Here is a picture showing the size difference of the 1970 caps and new caps. The big one is 100V 2200uF, the tall skinny on is 35V 2200 uF and the two coupling caps are 50V 2200 uF. Now how am I going to make this look good?
    sx9000-1 001.JPG
     
  9. Oldsansui441

    Oldsansui441 AK Subscriber Subscriber

    Messages:
    1,200
    Location:
    Victoria, Australia
    This will be a very interesting build, thanks for the photos. I thought they would have had more filter capacitance for 50wpc.

    All the best with it :thumbsup:.
     
  10. patra710

    patra710 Active Member

    Messages:
    188
    Location:
    Beecher, IL
    Cap coupled outputs, the first one that I have done. I don't quite understand just how they work. My first power output test I got 22 V AC rms across my dummy loads, about 60 watts.
     

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