Small job on AU999, BIG job on AU-X1

Discussion in 'Exclusively Sansui' started by kevzep, Jul 29, 2016.

  1. kevzep

    kevzep Its all about the Music Subscriber

    Thought I'd get back to this thread, I have been sidetracked from this X1 project, work, and other things have come into play which has had this on hiatus for nearly a year....
    I did a job on a QRX8001, and major rebuild on a Pioneer SX1980, and no it seems like the right time to get this AU-X1 going. The owner doesn't want to sink too much into it, but I am sure we'll be able to get it going and running okay....
    Here's the thread on the Pioneer if anyone's interested...http://audiokarma.org/forums/index.php?threads/sx1980-power-supply-board-oh-noooooooo.770852/

    So this is where we're at, making lists of caps including all "black Flags"..... Its a JDM (Japanese domestic model) so 100V, I have a large access to quite a few 230V>110V transformers so I'm going to go through them and find one as close to 100V as possible, there will be one there somewhere...
    It looks like this at the moment...
    IMG_4654.JPG IMG_4655.JPG IMG_4656.JPG
     
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  2. Overundr1

    Overundr1 AK Subscriber Subscriber

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    Ewwwww :(
    What a nightmare to work on, that switch board looks like it was thought out by a committee of folks that were not on the same page compared to typical Sansui design.
     
    Last edited: Jun 20, 2017
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  3. smurfer77

    smurfer77 AK Subscriber Subscriber

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    kev, looking forward to your posts on the X1. I have a couple of X11 sitting around waiting to be repaired. What needs repairing on your X1? Or it's a runner that you are future proofing?
     
  4. kevzep

    kevzep Its all about the Music Subscriber

    The owner is not sure, he bought it out of Japan, it was supposed to be running, but I have already found some fusible resistors on the driver boards that have gone hi.....so it can't have been running...
    But we are jut going to go through and do some preventative maintenance and get her running...hopefully.

    Oh totally, its a complete turd of a thing to work on, not easily serviceable....so I had better get it right otherwise its going to get boring pulling those driver boards in and out!!
     
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  5. ghamilton

    ghamilton Super Member

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  6. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    You may have already found them Kev, but there are a couple of 390ohm resistors on each driver board, (R36 & R37) that get completely shagged (that's 'falling apart shagged' :)) - resulting in no bias. ;)

    If yours seem OK I'd recommend changing them anyway.
     
    Last edited: Jun 19, 2017
  7. kevzep

    kevzep Its all about the Music Subscriber

    Yeah I totally found those, they were very high, reading up in the MΩ range so swapped those out, they were bad on both drivers boards....

    I also saw that ground mod with the star arrangement of those caps.....

    We'll see what the owner wants to do, I priced up the parts yesterday, minimum to get this beast running, and it was actually very expensive....
    I emailed him yesterday so I'll see what he says....He might even be watching this thread......:yikes:
     
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  8. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    If he is watching, the AU-X1 is very special - it isn't just another Sansui amplifier, it is a statement piece, and sounds like it too. :music:
     
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  9. kevzep

    kevzep Its all about the Music Subscriber

    Yeah I am pretty keen to hear it to be honest....
     
  10. kevzep

    kevzep Its all about the Music Subscriber

    Mouser order in, I hope I haven't forgotten anything, might be able to get started on this in the weekend!!
     
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  11. smurfer77

    smurfer77 AK Subscriber Subscriber

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    Kev, how are the output transistors? planning on any mods to main amp board for stability? (was there some service bulletin? I don't remember. I do think the shunt cap at input side of FETs on main amp board could be changed in value to bandwidth, but this might be going against the philosophy of the design).
     
  12. kevzep

    kevzep Its all about the Music Subscriber

    Outputs are good, this is a late model X1 as far as I can determine, it has the updated grounding scheme, as I get further into it I'll know more.
    I saw a ground mod on the pre-amp board in one of the threads here and I will be doing that one.
    I'd have to have a look at those shunt caps and figure out whats going on there.....
    Should be an interesting journey working on this....
     
  13. smurfer77

    smurfer77 AK Subscriber Subscriber

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    Cool, you are lucky with the outputs! Looking forward to the rest of the story. The cap I'm looking at increasing is the 100pF at C01 on the driver board F-2775. (well I don't have the AU-X1, I have two AU-X11).
     
  14. kevzep

    kevzep Its all about the Music Subscriber

    Copy that!! I'll look into this!!
     
  15. kevzep

    kevzep Its all about the Music Subscriber

    So the order turned up today, so I was able to make start. Unfortunately, I screwed the order up a bit, I missed a few of the mica caps.
    No problem, they are already on their way overnight from Australia.
    I'm out on a show tomorrow so I wont get back to this until Wednesday....

    So I started, did one driver board as much as I could, just waiting on one cap value to arrive to complete that, replaced all electro and Sliver Mica caps (except C03). Replaced R36 and R37 with 390Ω Metal film. So I left the other one until I have everything

    Got both MC Head amp boards done, then the Flat amp boards, these too have a couple of mica caps I am waiting on as well.

    There are a LOT of caps in this amplifier, unbelievable in fact!! This job is going to take quite some time I am thinking...So I just started and made a bit of headway today. LOTS of plastic bags full of electro caps on the bench to sort out.....

    I'll clean switches and what not as I go, its pretty clean this amp, low miles, one careful lady owner....
    Couple of pictures showing how we are progressing, it really just seems like I am relocating this thing on the bench all the time and not getting anywhere with it, and then there's those Crown Macrotechs I have to do as well...
    One thing I noticed, there was a cap on the driver board that was never soldered, factory error, had simply never made contact with the solder pad....I tried to catch a picture of it, y9u can sort of see it.
    IMG_4668.JPG IMG_4669.JPG IMG_4670.JPG IMG_4672.JPG IMG_4673.JPG IMG_4674.JPG IMG_4675.JPG IMG_4677.JPG IMG_4678.JPG
     
  16. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    Brings back memories. :)
     
  17. smurfer77

    smurfer77 AK Subscriber Subscriber

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    Thanks for the pics Kev. Yeah, when I ordered parts for my AU-X11 I got a shock when I saw the price... it was more than I spend on most full recaps, and this is only the driver boards! To be fair my drivers boards were in bad shape and are getting a full restuffing almost.
     
  18. kevzep

    kevzep Its all about the Music Subscriber

    Yes correct!! It's an expensive parts order!! Those Mica caps are not cheap....

    Hopefully I don't unearth a horror show when its time to fire it up and have to do another order....
     
  19. Overundr1

    Overundr1 AK Subscriber Subscriber

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    Bench edge multi angle vise envy over here, dangnabbit another goodie to add as that looks more sturdy than the large helping hands stand I use now. Also, I recently switched lighting over my own bench and the rest of the shop to led 4' lighting fixtures, far better than florescent tubes, seems to be less shadowing of the work area. Might also add grumble grumble about folks that repair loose knobs on expensive components by using epoxy to attach them to the shaft geez :(
    Looks like the total parts count for the restoration will rival some of the big quad receivers.
     
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  20. ghazzer

    ghazzer Sansui addict Subscriber

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    I admire your stamina for being able to work on this for hours at a time, until you get it done. I am too easily distracted, and too easily frustrated when things don't always work out as planned.

    Never the less, successfully rescuing one of these beauties is quite rewarding no matter how long it takes. Thanks for the pics and your narrative.

    Enjoy - - -
     

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