Small job on AU999, BIG job on AU-X1

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

  1. Hipocrates

    Hipocrates Anti-Muppet Subscriber

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    Very nice! :rockon:
     
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  2. kevzep

    kevzep Its all about the Music Subscriber

    Oh I forgot to mention, the MM and MC boards, I had to unplug those and then remove the gold plated molex connector sockets and tighten them all up, they were all in varying degrees, not making very good contact, I was getting some random earthing and DC pops through the phono inputs....After I tightened and remounted them, all is well....

    Thanks for the kind words John, much appreciated....

    Yes into the world of tuners, I have two to do immediately when I get the full complement of gear, I'll do the G7700 and my JVC5446 as well, just to get my eye in....I also have a friends Sansui TU5900 and his Akai AA920 also, so I'll have plenty of practice....
     
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  3. ghazzer

    ghazzer Sansui addict Subscriber

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    I suspect that it feels good to have the X1 percolating, AND you lab all organized! I hope they both last.

    I also hope that you will be able to describe the mystic of tuner alignment as well as you have done with your receiver repairs. I think that Arkay mentioned an FM station that he likes in HK - I'd really be impressed if you could pull that one in with your G-7700 - - -
     
  4. kevzep

    kevzep Its all about the Music Subscriber

    Thanks Steve, I will share the Tuner stuff here once I find my stride with it, I am pretty confident its something I have a feel for, just waiting for the last few bits of test gear to turn up...

    DAMN!! So I have had the X1 running at low to moderate listening levels all day, must have been running for 10hrs or more, then "CLICK", into protection, not sure what has caused this, the amplifier is actually still functioning, no DC on the output.....So, seems like there may be a gremlin in the protect circuit, this is going to be tricky to track down.....
    All good though, like a challenge!!

    All this while I am diving head first into my G7700......thought I'd do a quick re-cap....Hahahaha, I'll start another thread on that soon...
     
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  5. ManyMoonsAudio

    ManyMoonsAudio AKA paul79 Sponsor Subscriber

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    Likely a flaked out transistor that didn't like new life :) Nice work though. You tackled a monster there. I have worked on a couple of them and they are really fantastic sounding amps.

    Ever heard the BA-F1 and the CA-F1? These have a very similar sonic signature. I actually prefer this set over the X1 for musicality. They really got these right.
     
  6. kevzep

    kevzep Its all about the Music Subscriber

    Yeah that's what I'm thinking, some dirty old leaky transistor.....I'll dive into it once I get my G7700 running....I don't think it will take long, luck last words!!
     
  7. kevzep

    kevzep Its all about the Music Subscriber

    Well, I have gone through this extensively in the last few hours monitoring voltages etc, I have had to take a bit of a guess as to what it might be because of course, when I fired it up, it came out of protection.
    I had a couple of SCR's left over from another job, so I have replaced that, I remember the one in my G22000 went flaky......So I have had it running for a while now and its all good, I will run it on Thurs and Fri all day again as I have a big project on so I can monitor it all day while I work.
    When I turned it on just now, it came out of protection a lot quicker than it has been doing so hopefully its all good now....
    Can't be much else.....
    There it is, upside down on the bench again!!
    IMG_4764.JPG
     
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  8. ghazzer

    ghazzer Sansui addict Subscriber

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    Interesting. The only protection circuit I have analyzed is the HA12002 in the G-5700,6700&7700. I'll D'L the schematic and try to comprehend what you are doing. That will be delayed at least a week until I get back from Nashville.

    It would be interesting to see how Sansui's approach to protection circuits evolved over the years.
     
  9. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    Kev, what did you use as the replacement for the 2SF656? - same device or a substitute?
     
  10. kevzep

    kevzep Its all about the Music Subscriber

    I used a 2N5064, its a 200V device, the original is 100V, I put them in my G9000 and G22000.

    I actually suspect the originals ran close to the margin and could be damaged by the amp having a decent DC spike though the output.
    Now, this happened to this X1 when I first ran a turntable though the MM input, we had intermittent issues with the gold plated molex sockets, I had quite a bad hum through the MM input, so barely touched the MM card and "BANG", put the amp straight into protect. I thought I had fixed the issue, and tried it again, this time without the speakers on!! Same thing, so I suspect the already fragile and aging SCR was damaged...
    At least that's my theory.....
     
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  11. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    Thanks Kev. :thumbsup:
     
  12. cnolanh

    cnolanh Ad astra Subscriber

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    While I've never listened to an AU-X1 amp, for several years I did have a TU-X1 and I can report that its outrageous build and component quality produced the most beautiful, least noisy, most sensitive FM reception that I've ever experienced. I had no idea that AM could sound that good, either. Thirty-nine pounds of Sansui radio = bliss. Maybe you'll find one of those next? :music:
     
  13. Willy6

    Willy6 AK Subscriber Subscriber

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    Dumb question from a noobie..What exactly is an SCR ?
     
  14. AUD101

    AUD101 Parsley The Lion!

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  15. AUD101

    AUD101 Parsley The Lion!

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    A pin for pin replacement that I have used for the 2SF656 (although overkill) is the X0402MF - note it is a TO202-3 package which is a little bulky (compared to the 2SF656's TO92 package) so will need to confirm space availability etc
     
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  16. Willy6

    Willy6 AK Subscriber Subscriber

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    So are those SCRs normally located in the protection circuit like it is on the X-1?
     
  17. kevzep

    kevzep Its all about the Music Subscriber

    Yes they are, correct...

    TO202 would easily fit into the space the X1 has, plenty of room.
     
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  18. kevzep

    kevzep Its all about the Music Subscriber

    Well, very good things happened today.
    I have been running the X1 with the new SCR for two days now, its nearly been on for 10hrs today and its not missed a beat, I'm very pleased with that.

    Next after three days of serious trouble shooting and measuring, and measuring, staring at schematics and service manuals for this Marconi 2018 RF generator, I finally found the issue with that.
    What a horrifically complicated beast!! Boards and more boards I think there are 12 different circuit board in it, and lots of sensitive components. At least I fully understand how it works now, I quite enjoy working up the RF range, although even my 300mhz Tek scope was struggling at times!!
    It turned out to be a small TO50 package 5ghz transistor at the front end of the frequency divider, I was quite pleased it wasn't the RF amplifier which I thought it might be. However the replacement is a very small surface mount SOT23 device, was interesting dealing wit that I can tell you!!
    So, relieved to get the Marconi back to operational and very pleased the X1 is behaving, although I did leave the lid off it today, and you know I kind of like the look of it without the lid on, its very presentable like that and perhaps Sansui intended for it to be like that as an option? Little bit like McIntosh with their exposed transformers and heatsinks...
    Few pics, including the Marconi I was working on today...the scope is showing 90mhz, right up in the FM band!!

    IMG_4765.JPG IMG_4768.JPG IMG_4769.JPG IMG_4770.JPG
     
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  19. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    Well done Kev, that can't have been easy to find. :thumbsup:
     
  20. kevzep

    kevzep Its all about the Music Subscriber

    You're not wrong, the RF gen is so complicated, so I was trying to learn how it worked at the same time as fault finding, it was last night as more if it was soaking in to my brain that I decided where the fault must be....
    Was a bit of a giggle when I was sitting there looking at this SOT23 transistor on the bench here and wondering how on earth I was going to deal with it, can only be 3mm at the biggest.....

    Very relieved now though, and the X1 was just singing all day....excellent....:music:
     
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