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Sansui G-22000 Restoration/Upgrade Thread

Discussion in 'Exclusively Sansui' started by mattsd, Oct 28, 2018.

  1. mattsd

    mattsd AK Subscriber Subscriber

    Messages:
    1,632
    Location:
    Cincinnati, Ohio
    At last, I can finally get this started. The AU-919 is basically done, just waiting for some extra potentiometers to come in. Some overall pics and one board for now, I will be starting with the tuner/preamp section.

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    TONE AMP BOARD and TONE CONTROL BOARD (F-2890 and F-2889)

    Before

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    C01 and 03 along with C02 and C04 form a 5uF "bi-polar cap" and is bypassed with a .047uF mylar film cap (C05 and C06). These were replaced with a single 4.7uF Panasonic ECW polypropylene with a jumper placed to allow for maximum lead spacing to accommodate the big poly cap. C05 and C06 were removed.

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    C13 and C14 are 47uF 25v bi-polar caps and were replaced with 47uF 35v ES bi-polar caps. C15 and C16 are 22uF 25v bi-polar and were replaced with 22uF 35v ES bi-polar caps. The 0.1uF bypass caps for C13 and C14 (C09 and C10) were replaced with a 0.1uF Wima MKP10. The 2SA872 input pairs (TR01-04) were replaced with matched KSA992. The small mylar films for the tone EQ were all replaced with Wima MKP and FKP.

    [​IMG]
     

     

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  2. kevzep

    kevzep Its all about the Music Subscriber

    Excellent Matt, this is exactly what I was going to do!! As soon as I get some time, I will be putting my 22000 on the bench for a bit of love and some upgrades, and this was the first thing on the list.
    I think the flat amp and the phono pre has the same set up with the coupling caps.
     
  3. mattsd

    mattsd AK Subscriber Subscriber

    Messages:
    1,632
    Location:
    Cincinnati, Ohio
    Left and Right Flat Amp Boards (F-2899)

    Note: I marked the boards L and R for easier identification.

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    The flat amp boards on this unit are very simple to redo, just a few caps and a potentiometer to replace. The output high-pass filter consists of two 100uF 35v caps back-to-back (C10 and C11), forming a 50uF "bi-polar" cap. I replaced it with a single 47uF Nichicon ES and jumpered the empty position. It is bypassed by C09, a .22uF mylar. Interestingly, the bypass cap position offers the option for three different lead spacings, 15, 25 and 30mm. I used a .22uF Wima MKP10 with 15mm lead spacing. I may experiment with larger bypass values later, as these boards are extremely easy to get to and work on. C901 is a 1uF 50v mounted on the back of the board and is bypassed by C06, a .047uF mylar. I replaced it with a 1uF Wima MKS4, removing C06 and putting the Wima there. The pot was replaced by a Bourns 25 turn.

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    After:

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    Next post will have the EQ amp boards!
     
    Hyperion likes this.
  4. The Fuxtor

    The Fuxtor AK Subscriber Subscriber

    Messages:
    2,756
    Location:
    Calgary, Alberta
    how nice to have all the boards modular! Nice work too!
     
  5. kevzep

    kevzep Its all about the Music Subscriber

    Yeah the G22000 is a nice unit to work on, plenty of room and modular by design.
     
  6. mattsd

    mattsd AK Subscriber Subscriber

    Messages:
    1,632
    Location:
    Cincinnati, Ohio
    Left and Right EQ Amp Boards (F-2880)

    Up now are the EQ amp boards. The separate boards for the left and right channels is amazing to see and shows Sansui really went all out on this receiver, even the bypass cap for the high pass filter is a polycarbonate, very expensive for the time.

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    The high pass filter caps are mounted somewhat awkwardly on this board. Note I had already removed the 1uF cap and moved the jumper aside for the second board.

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    These boards share several similarities to the flat amp boards, but they are different. C901 is again a 1uF 50v bypassed with C06, a .047uF cap sitting on top of the board. This was removed and a 1uF Wima film was put in place of it. The trim pot was replaced with a Bourns 25 turn. The mylar RIAA caps (C10 and C12) were replaced with same value Rifa PHE426 polypropylene caps. The output high pass filter is comprised of two 47uF 25v caps back-to-back (C902 and C903) to form a 23.5uF "bi-polar" cap and bypassed by a 4.7uF polycarbonate (C09). Note the lead holes for the bypass cap allow for 15, 25 and 30mm lead spacings like the flat amp boards. The 4.7uF was replaced by a Panasonic ECW polypropylene film and a single 22uF 35v Nichicon ES was put in place of the two 47uF caps. The ES cap was mounted by first bending the leads in a half circle approximately 15 mm wide, then I put one lead through the hole, soldered it and and clipped it off on the front of the board like so:

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    The process was repeated for the other lead, the end result comes out quite nicely and the cap fits perfectly into the empty space between the solder pads:

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    A little dab of glue to hold it in place along with dampening resonance and voila! We have completed boards!

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    Up in the next post, the two "motherboards" that hold the EQ and flat amp boards along with the power supply.
     
    Last edited: Nov 2, 2018

     

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  7. kevzep

    kevzep Its all about the Music Subscriber

    I like the thought thats going into this Matt, very nice.....
     
  8. LBPete

    LBPete Rolling Along Subscriber

    Messages:
    11,521
    Location:
    Long Beach, CA
    Very nice indeed!

    - Pete
     
  9. LPhillips

    LPhillips New Member

    Messages:
    36
    What a talent ! Those boards are a work of art.
     
  10. Robisme

    Robisme Sansui Enthusiast Subscriber

    Messages:
    11,732
    Location:
    Martinez California
    Looking great.

    Rob
     
  11. Overundr1

    Overundr1 AK Subscriber Subscriber

    Messages:
    2,515
    Location:
    Mississippi
    Those 2SK131 dual jfets are getting very hard to source these days. Might consider finding a couple to 'stash' away just in case. Also, any thought to replacing the smaller value green mylar caps, they are also starting to become problem children from time to time. Nice restoration sir.
    -Lee
     
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  12. kevzep

    kevzep Its all about the Music Subscriber

    Im starting to get rid of these whenever I am inside units now, I have had a few dodgy ones lately, the worst one was in my G9000. Base resistor bypass cap on one of the drivers, randomly the cap would short and then the bias at idle would jump from 15mV to 150mV....took me a good few attempts to find the issue.....
     
  13. LBPete

    LBPete Rolling Along Subscriber

    Messages:
    11,521
    Location:
    Long Beach, CA
    I had a shorted green mylar cap in a G-5500 recently. Drove me crazy for awhile. I've also had a shorted ceramic cap on a 9090DB driver board. It kept the output transistors turned on. Ah, the joys of vintage equipment.

    - Pete
     
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  14. kevzep

    kevzep Its all about the Music Subscriber

    We are going to start seeing more of this sort of thing, so thinking outside the box is becoming more necessary these days....
    More evidence that those green caps have to go!!
     
  15. Hipocrates

    Hipocrates Anti-Muppet Subscriber

    Messages:
    1,740
    Location:
    Costa Rica
    I've seen some like this
    CIMG0251.JPG
     
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  16. Oerets

    Oerets AK Subscriber Subscriber

    Messages:
    10,540
    Location:
    Derby City U.S.A.
    Looking good!
    Will have to make the trip up to give it a listen once it is completed.


    :thumbsup::thumbsup:
     

     

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  17. bktheking

    bktheking Gitter Done! Subscriber

    Messages:
    12,864
    Location:
    Ottawa Ontario
    Doing a 33000 myself right now, i feel your pain, these are filled with caps.
     
  18. kevzep

    kevzep Its all about the Music Subscriber

    Pain? I like working on these amps, I feel they are easy and quite serviceable.......
     
  19. bktheking

    bktheking Gitter Done! Subscriber

    Messages:
    12,864
    Location:
    Ottawa Ontario
    Just a lot of parts, i'm almost done the amp. I do agree from the serviceable standpoint, it's just a lot of components i find.
     
  20. kevzep

    kevzep Its all about the Music Subscriber

    Oh yeah for sure there is a lot to it. 7 relays for example!!
    I did mine when I got it nearly 8 years ago, but its time to go through it again and upgrade a few things, I have done some of it, just a few more things to do in the pre-amp section and to align the tuner, I am looking forward to that!!
     

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