Sansui AU-217 Restoration

Discussion in 'Exclusively Sansui' started by dedero, Feb 6, 2017.

  1. Soundphile

    Soundphile Active Member

    Messages:
    211
    Location:
    Kuala Lumpur, Malaysia
    I have an AU 217 too. Three years ago, I replaced all the Caps with Nichicon, Panasonic and WIMA (for caps upto 10uF). The fusing resistors & trimpots were also replaced. Bias reset. The amplifier sounded much better after this.
    Two years ago, I replaced ALL the resistors with 1% metal film resistors. The sound quality improved signifcantly again. AM very happy with the amplifier. It plays a few hours every day and dosen't miss a beat.
    You won't regret restoring this little workhorse of an amp.
    Have fun.
     
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  2. Soundphile

    Soundphile Active Member

    Messages:
    211
    Location:
    Kuala Lumpur, Malaysia
    Surprisingly, the differential input pair 2SA798 held up very well. Only recently has the DC offset started to flucuate.
    I've already received Fairchild KSA992 tranistors to replace the 2SA798s.
    After this, hopefully, the amp will continue to deliver many years of excellent service.
     
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  3. dedero

    dedero New Member

    Messages:
    16
    Location:
    Bavaria - Germany
    Very good hint, thanks a lot!! I just ordered 2 x Bourns 3296Y 500ohm in stock in Mouser, I will let you know after I install them and tune the DC offset

    Thanks for the info!, I will test everything again after changing the trimpots and re-adjust the DC offset again, actually I was re-testing again without any input and the strange thing is, when the amplifier is off for quite long (condensors empty) there is no pop noise during the turn on but when aI turn it off and turn on back again the loud pop comes up and it happens only during the turn on, no loud pop during turn off

    Thank you all for sharing your expriences!!
     
  4. dedero

    dedero New Member

    Messages:
    16
    Location:
    Bavaria - Germany
    Wow! ALL resistors?!, that sounds like a challenge, so as per your experience, the resistors can also wear with time alonside with condensors (without of course the chemical part)
    EDIT: Actually I didn't regreat at all with the restoration! on the contrary, I'm extremely happy with such refurb!
     
  5. pete_mac

    pete_mac Super Member

    Messages:
    2,853
    Location:
    Sydney, Australia
    It's not so much a matter of 'wear', but the different sonic characteristics of metal film resistors vs carbon film resistors.
     
  6. Soundphile

    Soundphile Active Member

    Messages:
    211
    Location:
    Kuala Lumpur, Malaysia
    Thanks for your comments dedero and pete-mac. I am still on a learning curve. There are many interesting comments and write-ups on the benefits of metal film resistors. Since the 217 has a rather simple architecture, it was not too difficult or time consuming to replace the resistors. So I gave it a go and WOW ... the improvement in audio quality surprised me. I now use the 217 to also drive the main front Left & Right channels of my Blu Ray player.
    Please allow me to share an experience when listening to the "Overtime" Blu Ray by Lee Ritenour. There is a track "Mizrab"and a few others which has a bass solo and for the first time, I could actually clearly hear all the different bass notes. Whereas in the past (prior to metal film), the bass notes were not clearly differentiated. In addition, Diana Krall, Julie London, Norah Jones, Cassendra Wilson, Ray Charles, Miles Davis, Dave Brubeck, Bill Evans all came alive with a new vigour.
    pete-mac may well be right that it may be due to different sonic characteristics. However, I could not help but notice much greater detail, clarity, soundstage and transparency. From what I've read, here in AK and other sites, cc resistors tend to less tight loose tolerances (up to 20%?) as well as vary in their resistence and the audio frequency bandwith as the resistor temp changes. I can only imagine the sum total of signal & detail loss as the audio travels though all such (aging) cc resistors in the signal path.
    The "experiment" with 1% metal film in the AU 217 was indeed rewarding and satisfying. Finally, I do wonder how the higher end Sansuis would sound if totally fitted with 1% metal films.
     
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  7. dedero

    dedero New Member

    Messages:
    16
    Location:
    Bavaria - Germany
    That's awesome!, thanks for sharing your experience, I will really consider doing something like that then!

    I'll keep you posted with details

    Cheers,
    Bruno.
     
  8. dedero

    dedero New Member

    Messages:
    16
    Location:
    Bavaria - Germany
    Hi All,

    Okey then, after quite a "while" I officially finished this restoration, I received the 500ohm Bourns 3296Y-1-501LF multi turn (specifically this model fits perfect with the pins layout), thank you guys for the confirmation as 500ohm replacement instead of the factory 470ohm one!

    DC Bias adjustment manual instructions:

    DC Adjustment at 7mv as specified (with the new trimpots in the background):

    I'm not really sure whether this trimpot replacement was the solution for the loud pop but I cannot hear it anymore... @Leestereo I was taking a look in google and different forums and I couldn't find the expected values for DC offset at the speaker terminals, in case you have some information, please let me know!

    Thank you all for your help and awesome support! :rockon:

    PS: I bought an AU-317 last week and needs some love as well, AU-317 restoration coming in a near future!

    Cheers!,
    Bruno.
     
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  9. Leestereo

    Leestereo Super Member

    Messages:
    2,154
    Location:
    Ottawa, ON
    Ideally for a direct coupled amplifier, the DC offset should be 0mV; however in the real world, <50mV is still acceptable.
     
  10. cavemanRTR

    cavemanRTR New Member

    Messages:
    9
    Location:
    NW Ohio
    Kind of new here, I just recapped my Sansui AU-217 and it was my first attempt. I bought all new ELNA SimicII for all of the polarized caps and Nichicon MUSE bipolar for the non-polarized ones. The power supply caps I replaced with 2-pin Mundorf M-LYTIC AG+ 10,000uf 63 volt caps. I made 3D printed adapters to mount the Mundorfs with supplied mounting discs and 14 gage silver wire to get the board's hole spacing to the AG+'s 10mm pins. I adjusted the DC off sets, cleaned the switches and the "pots" volume, bass, treble, and balance. I have also replace the spring speaker terminals with 5-binding posts, I had a machinist friend make a plate that fit the case. How does one post pictures? I could show everyone. These terminals were rewired with 14 gage silver Teflon wire from the headphone jack board then back to the main board. As soon as I get the 200 break-in hours on the AG+ caps I'm going to connect it to my Merlin TSM-MMM's for a serious listen. Currently the overall sound is very pleasing, bass notes are clean and powerful, mid-range is sweet, treble is clear.
     
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  11. dedero

    dedero New Member

    Messages:
    16
    Location:
    Bavaria - Germany
    Hi!, great details and work! would be great to see how it looks, you can upload pictures pressing the "upload a file" button next to "post reply" for further details you can read this post: http://audiokarma.org/forums/index.php?threads/posting-pictures.733929/
    Cheers!
    Bruno.
     

     

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  12. AUD101

    AUD101 Parsley The Lion!

    Messages:
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    Location:
    "The Big Smoke" - UK
    cavemanRTR - +1 - would like to see pic's of your AU-217 Restoration...especially the mounting adapters/discs/wiring for the 2-pin Mundorf M-LYTIC AG+ 10,000uf 63 volt caps
     
  13. cavemanRTR

    cavemanRTR New Member

    Messages:
    9
    Location:
    NW Ohio
    Here is the machined part:
    Boards with new SilmicII's
     

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  14. cavemanRTR

    cavemanRTR New Member

    Messages:
    9
    Location:
    NW Ohio
    New binding posts
     

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  15. cavemanRTR

    cavemanRTR New Member

    Messages:
    9
    Location:
    NW Ohio
    dedero thanks it works! Learned something new today!
    Here is the Mundorf cap on to of the OEM. The OEM's have blank pins to help hold it it place. On the Mundorf's I got extra double stick rings and used them top and bottom of the 3d printed spacers. (thought about using screws through the (2) empty pin holes to mount the spacer) Spacer to board, cap to spacer. The spacer are just high enough to keep the pins from touching the board, I wire wrapped around the pin and routed them outwards so they would fit into the board. the 14 Gage wire I had was made from 28 strands of some other size wire to make it 14 gage then with Teflon coating. I used naked wire as the 14 Gage wouldn't fit though the board, I think I removed 6 or 8 strands before it would fit through the PC board.
     

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  16. cavemanRTR

    cavemanRTR New Member

    Messages:
    9
    Location:
    NW Ohio
    It plays great on the 2nd system in the bedroom, but when I moved it to the other room with the TSM's the left channel wouldn't work. I put is back in the 2nd system and with works again so I must have a cold solder joint somewhere. I just set it on a cardboard box to hook to the TSM's. My current project is a Sony TA-F60 recap (paid $25 with all packing material and all manuals and working), so when this is done. I can get the Sansui back to check over. At some point I have a TU-317 to redo for a matched set.
     

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  17. cavemanRTR

    cavemanRTR New Member

    Messages:
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    Location:
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    dedero,
    Sorry I did take pictures of the rewire, but the mounting disc tape things I got from Parts Coniexon when I bought the caps, there a option to buy them separately . Since I have never did anything like electronic repair before I was willing to try them, I think those tape rings saved me butt. My first component system was a Sansui 350 receiver, RIP, since then Sansui was the AU/TU-7500 which was taken and this AU-217/TU-317 system. Current main system is the Emotiva, but after recapping the Sansui, I think I prefer the Sansui's 'new" sound: the general definition, low level details, dynamics, punch. Not bad for a 30 watt integrated amp. There is something to be stated of the Sansui House Sound, they had something figured out.
     
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  18. mcgjohn

    mcgjohn Active Member

    Messages:
    133
    Location:
    Chicago area


    SHould not be too bad a project. I have rebuilt 3 217s. They are nice amps. The main thing you want to do as you remove the older caps, is gently work that glue off the pcb. It takes some time, but I found normal IPA will soften it so you can work it loose with a wooden stick. Don't use a screw driver blade since that will scratch the pcb.

    tons of options on caps from Mouser or digikey. On the last 217 I rebuilt, one of the leads on a main filter cap was completely gone, yet the amp still was able to function....
     

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