AU-999 Mystery components and power switch quesions

Discussion in 'Exclusively Sansui' started by DCinDC, Mar 19, 2012.

  1. DCinDC

    DCinDC I'm here to fix it

    Messages:
    4,402
    Location:
    Northern VA
    I'm going thru a pair of AU-999 amplifiers, and I find that one of them has a few caps and resistors mounted on a tag board underneath. Pics are below. They are between the driver to66 sockets and the main filter caps in the pics.

    I've looked at other pics of 999s on the net and see that some other ones have these parts too. I can't find them on the schematics. Anyone know what they are for? They appear to be wired into the front tone and filter boards.

    I need a new microswitch for the power switch assy. Does anyone have a good part number? Also, there are other terminals on the wafer part of the power switch that look like they are going to the phono preamp board. Anyone know what these do and how they are wired?
     

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  2. skippy124

    skippy124 Super Member

    Messages:
    1,605
    Location:
    Sydney Australia
    Hi,

    The 999 I recently acquired has those "mystery components". If no one else posts up an explanation I'll have a look tonight and see if I can offer an explanation. I think mine is an early build (serial number has been damaged and is hard to read) and the circuit diagram may be for a later build version, or it could be vice versa.

    Likewise with the power switch, I have looked over the schematic and can't find S18(b) anywhere.

    Cheers

    John
     
  3. tobyj17

    tobyj17 Comfortably Numb

    Messages:
    2,445
    Location:
    Wisconsin's west coast
    Mine has them too. Can't tell you what they're for though. Maybe Kevzep has an answer..he knows these things pretty well.
     
  4. avionic

    avionic " Black Knights " Subscriber

    Messages:
    41,245
    Location:
    Fort Dodge, Iowa
    D001 Encapsulated bridged rectifier ---- 200v /4A ----- 5B2
    First bridged rectifier off of the power transformer..D001
    How could you miss it? LOL

    Just in case..
    http://www.mouser.com/ProductDetail...EpiMZZMuCl5o%2b/AuPoGFpF0jtIvA%2btueJHWbZEo8=

    Rectifying AC off the transformer to DC ..

    ----------------- Disreguard---------------------
     
    Last edited: Mar 20, 2012
  5. avionic

    avionic " Black Knights " Subscriber

    Messages:
    41,245
    Location:
    Fort Dodge, Iowa
    Could you provide a photo of said microswitch?
     
  6. skippy124

    skippy124 Super Member

    Messages:
    1,605
    Location:
    Sydney Australia
    Hi, I think the OP was describing in his words the "few caps and resistors mounted on a tag board underneath" as the mystery components - see the components circled in red in the pic below, and not the bridge rectifier circled in green..... that's how I read the post

    [​IMG]

    Cheers

    John
     

     

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  7. avionic

    avionic " Black Knights " Subscriber

    Messages:
    41,245
    Location:
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    Hey skippy
    S18a & b. is the power switches. Look for D601 and D602 just to the right of the F-1228 circuit schematic is where S18b is located ( it is connected to those two germanium diodes D601 and 602) in the schematic diagram.
     
    Last edited: Mar 20, 2012
  8. avionic

    avionic " Black Knights " Subscriber

    Messages:
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    Location:
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    Now that I actually read the inquisition.Yeah your right.Those may or may not be in the schematic. it will take a little circuit/component tracing to locate them in the schematic. They have shielded audio wire thats a clue.
     
    Last edited: Mar 20, 2012
  9. skippy124

    skippy124 Super Member

    Messages:
    1,605
    Location:
    Sydney Australia
    Yes, I think you are right and they aren't in the schematic. I think that these are early build units, and the available schematic is for a later build version.

    I might do some checking later tonight an see where they are connected.
     
  10. skippy124

    skippy124 Super Member

    Messages:
    1,605
    Location:
    Sydney Australia
    OK,

    I believe the mystery of the mystery components is solved. In the main schematic there is a block between the F1209 board and the amp driver board F1159 for each channel, and this is designated as the "Subsonic filter unit". Now have a look at the lower right hand side of the schematic..... the circuit of these filter units is shown, and this includes the pre-out/main in connections as well. The cap and resistor values and quantities line up with what is physically on the tag strips.

    Now just have to find that pesky S18b switch location.......

    Cheers

    John
     
    Last edited: Mar 20, 2012
  11. DCinDC

    DCinDC I'm here to fix it

    Messages:
    4,402
    Location:
    Northern VA
    Well! Now we're getting somewhere!

    My schematic has stock number 9236480 in the lower right corner.

    Mine shows an F-1228-1 phono preamp, and no diodes D601 and D602, and as far as I can find, no S18b.

    My "A" block in the lower right only shows the pre/main switching, no passive components in that block at all. Looks like this will work without the pre/main jumpers, as the connections are made by the speaker switch. Interesting.

    I don't have a pic of the power micro switch because they are both missing. But I just remembered that I have several from a Panasonic tape deck that I disassembled. It's the classic flat black microswitch with the little white nylon nub that sticks out. This is actuated by a cam on the physical power switch lever. I thought someone might be able to just post a part number I could find, from their memory. I will post a pic of the microswitch from the parts deck today.

    I could've traced all this out, but some wiring has been cut and removed, that I need to restore. And I can't imagine what the second section of the power switch might be doing.

    Can someone point me to an online earlier version of the schematic?
     

     

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  12. skippy124

    skippy124 Super Member

    Messages:
    1,605
    Location:
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    I can't find the second section of the power switch wiring on the schematic I have S18 is shown as having an "a" (power) and "B (????) section.

    Here is the subsonic filter information



    [​IMG]



    [​IMG]


    If you want a copy of the schematic I have shoot me a PM with your email address.

    Cheers

    John
     
  13. DCinDC

    DCinDC I'm here to fix it

    Messages:
    4,402
    Location:
    Northern VA
    hunh! Well that clears that up!

    Sent you PM, thanks a lot!
     
  14. DCinDC

    DCinDC I'm here to fix it

    Messages:
    4,402
    Location:
    Northern VA
    Got your schematic. thanks so much!
    The S18b is right where Avionic said it would be. You guys must have the same scheamtic! It's just to the right of the phono preamp board near the two diodes.

    I pulled the microswitch I had out of my parts bin and it's not large enough to mount to the power switch lever plate. So I am still on the lookout for a suitable P/N for that...

    Thanks for everyone's help!
     
  15. DCinDC

    DCinDC I'm here to fix it

    Messages:
    4,402
    Location:
    Northern VA
    If anyone finds this topic thru a search, the explanation of the secondary (wafer) section of the power switch is that it grounds out the phono preamp output thru two 1N60 diodes at power down.

    It's not in my schematic of the later models. And the diodes are not in my later AU-999, but are in the earlier one.

    221100275 is my early one
    222110217 is my later one.

    The only difference between the early and late phono stages is an additional filter capacitor near R607/608. So I guess they just determined it wasn't needed.
     
  16. DCinDC

    DCinDC I'm here to fix it

    Messages:
    4,402
    Location:
    Northern VA
    sunova....

    I found a proper microswitch in my junk drawer! Thanks old Panasonic cassette tape deck!

    It mounts and functions perfectly!

    Here's pics. The part number is VV-5-1A442-D. It's an Omron.
     

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  17. kevzep

    kevzep Its all about the Music Subscriber

    Well Skippy beat me to it...........Nice work.....there is a few revisions of this amo and things can get a bit confusing....

    It seems on some AU999 that the C speaker position is the only one which disconnects the Pre and the Main, it has "separated" in brackets next to the C indication on the speaker output selector.......Mine is like that....
     
  18. DCinDC

    DCinDC I'm here to fix it

    Messages:
    4,402
    Location:
    Northern VA
    tnks Kev!

    Yeah I pulled the jumpers and it works fine. Interesting feature. I'm sure I can use it.

    Apparently I will never find another micro switch anywhere else... I looked for hours today. What luck finding one in a cassette deck of all places!

    Does anybody have any donor switches? I need a power, muting, and a balance check switch for my other AU-999 which will soon be Franken-Fied.
     
  19. avionic

    avionic " Black Knights " Subscriber

    Messages:
    41,245
    Location:
    Fort Dodge, Iowa
    http://www.mouser.com/ProductDetail...GAEpiMZZMumBvQ1hY/fBVZIZbOGG%2bCJdcjKuU6vaB4=
    Omrom still makes'm just have different part numbers now.
     
    Last edited: Mar 20, 2012
  20. avionic

    avionic " Black Knights " Subscriber

    Messages:
    41,245
    Location:
    Fort Dodge, Iowa
    I'm looking at the schematic . The diodes are not on the F-1228 they are off to the side of the diagram.A couple 1N60 diodes.The S-18b switch atually grounds out the cathodes of those two diodes.

    http://www.hifiengine.com/manuals/sansui/au-999.shtml
     
    Last edited: Mar 20, 2012

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