AU-999 Restoration & Modification

Discussion in 'Exclusively Sansui' started by leray1, Jan 12, 2019.

  1. leray1

    leray1 AK Subscriber Subscriber

    Messages:
    460
    Location:
    Houma, LA
    This is my first undertaking of this magnitude, but after reading all the threads and claims of how easy it can be done, I decided to do it. Stereofun has been a big help so far, but he's probably tired of all my PMs:biggrin:

    I ordered all the parts based on stereofun's list and started working on it today.

    So far I have the subsonic filters removed. Before moving on, I need help.

    Is there an order that all of this should be done to make it easier?

    I'm gonna start with the main filter capacitors. How do you get them out of the clamps? Should I remove the driver boards and heatsinks, first? Do the driver boards just plug into the blue strip?

    I'm starting to get that "I'm in over my head feeling" in my gut. Can you ease my worries?
     
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  2. leray1

    leray1 AK Subscriber Subscriber

    Messages:
    460
    Location:
    Houma, LA
    I removed the driver boards and heatsinks that are around the filter caps to be able to get to the cinch screws.
     

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  3. kevzep

    kevzep Its all about the Music Subscriber

    Just undo the whole bracket from the chassis and pull the cap out with the bracket on it, then remove the bracket, take note of the polarity when you cut the wires off.
     
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  4. leray1

    leray1 AK Subscriber Subscriber

    Messages:
    460
    Location:
    Houma, LA
    Yeh, I was having trouble loosening the bracket mounting screws... felt like I was going to strip the heads, but I got them. The new caps are in place.

    I replaced the caps on the driver boards and then called it a day. It's slow going for this newbie, but it's going.
     
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  5. kevzep

    kevzep Its all about the Music Subscriber

    You need those JIS screwdrivers when working on the Japanese equipment..
     
  6. AnalogueBen

    AnalogueBen Active Member

    Messages:
    102
    Location:
    Gold Coast, Australia
    Take a few pics of every section that you work on.. this becomes invaluable when you may find a straywire or a component that you needed to desolder and cant remember where it came from.
    Download the service manual..check the caps polarity ON the board first,, sometimes the printing on the board/service manual is wrong so I always check this first and take notes of any errors.
    Definitely build yourself a dim bulb tester!
    We'll be here to guide so try not to make rushed mistakes (hey it happens).. but most of all have fun ;)
     
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  7. leray1

    leray1 AK Subscriber Subscriber

    Messages:
    460
    Location:
    Houma, LA
    Finished the filter caps today but this will be on hold until I get the rest of my parts. Should be tomorrow
     

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  8. leray1

    leray1 AK Subscriber Subscriber

    Messages:
    460
    Location:
    Houma, LA
    Should I use new insulators for the outputs? transistor insulators.jpg
     
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  9. slimecity

    slimecity Super Member

    Messages:
    3,242
    Location:
    New Zealand
    Practice will differ from person to person but......

    I would carefully examine the existing mica washers for any creases or parts broken off. If they appear OK, you can re-use them. Also ensure that you place a couple of dabs of new non-conductive silicone grease under the outputs when reinstating them.
     
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  10. leray1

    leray1 AK Subscriber Subscriber

    Messages:
    460
    Location:
    Houma, LA
    What you see on the heat sink is all there is. It's not mica but looks like clear film or tape.
     
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  11. Hipocrates

    Hipocrates Anti-Muppet Subscriber

    Messages:
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    I think is a good practice, clean it, new mica and thermal paste.
     
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  12. slimecity

    slimecity Super Member

    Messages:
    3,242
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    It should be mica.

    It wont cost much at all to use new ones.
     
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  13. stereofun

    stereofun Super Member

    Messages:
    1,295
    Location:
    Tucson, AZ
    Just do the check we talked about - where you set your meter to continuity check - then probe outputs metal casing vs heat sink - no beep should be heard. Its such a fast insurance policy to make sure the Mica is doing its job
     
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  14. markkb

    markkb Active Member

    Messages:
    216
    Location:
    Mountain View, CA
    Thanks for starting the thread, I'm going to do my 999 someday. I like the idea of powering up on a dim bulb tester after completing a section, so if a mistake is made it can be isolated to just the work completed. Have fun.
     
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  15. kevzep

    kevzep Its all about the Music Subscriber

    Not necessarily, that insulator looks fine, its not broken, it just has that awful grease they used to use back in those days.

    Looks exactly like a Mica Insulator to me, that is what they look like.
     
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  16. leray1

    leray1 AK Subscriber Subscriber

    Messages:
    460
    Location:
    Houma, LA
    This project was on hold for over a week due to another project. A good one though, I put a new floor in my music room. But I'm back at it and I finished the two driver boards after work today.

    It went well. I did lift and break half a pad for the same transistor on both boards. The way they bent the leads all the way to the board makes desoldering difficult.

    I used isopropanol to clean up excess flux but it kind of dulled the surface of the board. Is this normal?

    My next step is to change the rectifier. The replacement (see pic) is different. Do any of you have a pic of how you installed yours?
     

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  17. AnalogueBen

    AnalogueBen Active Member

    Messages:
    102
    Location:
    Gold Coast, Australia
    Coming along nicely now, cant say I've seen the isoprop do that before tho.

    I like to triple check that I've put the correct transistor in its location and got the leading correct too. Yours looks tidy, and yeah, sometimes desoldering is really frustrating.

    I'd upgrade your trimpots too, sooner the better. I used Bourns multi turn 3296P, the P is important as it suits this vertical board.

    2019-01-24 12.52.50.png
     
  18. leray1

    leray1 AK Subscriber Subscriber

    Messages:
    460
    Location:
    Houma, LA
    Yeh, there is corrosion on the pots. I was planning on trying to dial them in first but will probably just change them.

    The isoppropanol is 100%, lab grade. Maybe that's why?
     
  19. AnalogueBen

    AnalogueBen Active Member

    Messages:
    102
    Location:
    Gold Coast, Australia
    Yeah probably why. Ive got 98% I think but I use sparingly. now I only bother to clean around where I've worked using a q tip, think the flux is what gives our gear the vintage aroma when everything is warmed up haha
     
  20. leray1

    leray1 AK Subscriber Subscriber

    Messages:
    460
    Location:
    Houma, LA
    I replaced the outputs and the rectifier tonight. It went well but I should have put the filter caps in after replacing the outputs and reinstalling the heatsinks. The caps got in the way and made installing the outputs more difficult than it should have been.

    I drilled a hole in the chassis to mount the new rectifier with a nut and bolt. Looks nice and tidy (thanks stereofun).

    I will reinstall the driver boards and build a DBT tomorrow to check my work thus far.
     

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