The AU-X1 is, like, so hot right now.

Discussion in 'Exclusively Sansui' started by slimecity, Sep 24, 2017.

  1. slimecity

    slimecity Super Member

    Messages:
    1,732
    Location:
    New Zealand
    Cheers Hyperion - that helps a lot.

    Any advice on whether these are referred to in the SM as PC or MC? My understanding is that the blag flags may be polystyrene, is that the case?
     
  2. kevzep

    kevzep Its all about the Music Subscriber

    There is no short cut for this amp, you only get one chance, you will need to dismantle the amp, remove the front, get all those Black Silver Mica capacitors out of that amp. Whilst your in there you might as well just recap it all...
    Make a list and go for it, as tempting as it is to fire it up, I wouldn't. I would get your parts ordered and go through it in one go.....
    They aren't the easiest of things to pull apart so you only want to be doing it once.

    I used Silver Mica caps in place of the black flags, 300-500V range, not the cheapest either, you'll spend about $250NZ on parts, there are a lot of caps in that amp...

    Look at whats in the amp, forget the schematic, I never even used it to be honest....

    @Ronito6 they use those fusible resistors in that part of the circuit as current protection for the bias circuit. I think perhaps they should have used something a little more heavy duty there, but hard to know how far to let the current run away in the bias circuit before the resistors need to open up.....go too high and you might be in trouble, not enough and the resistors burn up......I suspect they went on the cautious side given the instability of this amp in the early days....but who knows....
     
    Hyperion and slimecity like this.
  3. Hyperion

    Hyperion Roobarb & Custard Subscriber

    Messages:
    39,475
    Location:
    Hertfordshire, UK
    I used ½ watt metal film replacements for those resistors but put them up off the board on ceramic beads, they have been fine - no signs of trouble.

    And agree wholeheartedly your comments regarding SM & Schematic indications of parts - just visually audit your own amp is best. ;)

    Silver Mica is a perfectly good choice for replacing the Black Flags which are Polystyrene (according to AK member ConradH's research). However, I used Ceramic C0G/NPO MLCC types with good results. There have been some discussions about the relative merits of either choice, all I can say is that either works well, but 'Ceramic C0G/NPO' is much cheaper. I also like the fact that the ceramics are really tiny, when you are dealing with capacitance as low as 3pf the physical size of the Black Flag (or its replacement) could give rise to 'strays' or unwanted 'pickup' - just my personal view on that last point.
     
    Last edited: Sep 26, 2017
    Ronito6 and slimecity like this.
  4. Hyperion

    Hyperion Roobarb & Custard Subscriber

    Messages:
    39,475
    Location:
    Hertfordshire, UK
    The Black Flags are usually referred to as 'PC' = Polystyrene Capacitor in the SM, but Note well that not all Polystyrenes in the amp are Black Flags.
     
    Ronito6 likes this.
  5. Overundr1

    Overundr1 AK Subscriber Subscriber

    Messages:
    2,278
    Location:
    Mississippi
    Never been in the X1 however (pinging John) are there any of those annoying green chicklet low value bi-polar caps that give us headaches in the lower x1x series?
    -Lee
     
    Hyperion likes this.
  6. Hyperion

    Hyperion Roobarb & Custard Subscriber

    Messages:
    39,475
    Location:
    Hertfordshire, UK
    I don't remember seeing any, capacitors of those values will either be Polystyrene, Polypropylene or Polyester, the last 2 likely being of the red or orange 'chicklet' variety. :)
     
  7. slimecity

    slimecity Super Member

    Messages:
    1,732
    Location:
    New Zealand
    Yes, noted - I see the traditional polystyrene types in there too.

    Thanks for the help peeps.

    I think Kevzep is right, I need to don scuba gear this weekend and dive into this bastard to do a black flag full stocktake - yikes......
     
  8. Ronito6

    Ronito6 Well-Known Member

    Messages:
    937
    The black flags are in the signal path. You will find them on the cards that populate the 2772 phono motherboard,the the 2775 driver boards, and the flat amp board.

    Working on the X1 is a massive task. But why climb mountains...eh?

    Thinking about it now, we look forward to basically :
    • a replacement of possibly iffy diodes like the VD1212s or MV03s
    • a replacement of all electrolyics
    • a finding and replacing noisy or just tired transistors
    • a replacing of all relays
    • a cleaning or reconditioning of switches and volume pots
    • RCA jack cleaning or replacement
    • new speaker posts(?)
    • lights replacement
    • and my most hated of all because the solution literally really, really, stinks and is messy ...glue elimination.
    Worth it!
     
    Last edited: Sep 26, 2017
    Hyperion and slimecity like this.
  9. slimecity

    slimecity Super Member

    Messages:
    1,732
    Location:
    New Zealand
    Thanks Ronito. This helps a lot.

    I know it sounds like a lot of work, but I think I will do things in 2 passes here - the first pass, replace all black flags & VD1212's & MV03's, and fuse resistors. Then test the amp. Then upgrade the caps.

    How will I know if the small relays are giving me trouble? I have seen posts where people have replaced these.
     
  10. Ronito6

    Ronito6 Well-Known Member

    Messages:
    937
    You will hear a low tone / hum suddenly while playing a record. But if you tap or gently press one of the small signal relays with a chopstick or a long trimmer pot adjustment tool, the hum will stop temporarily.

    That is how I sussed out the issue. The direct method.
     
    Hyperion and slimecity like this.
  11. kevzep

    kevzep Its all about the Music Subscriber

    One or the other channel may randomly drop out......I am going to have to do the relays in the X1 I did, they have started to play up...
     
    Hyperion, slimecity and Ronito6 like this.
  12. Ronito6

    Ronito6 Well-Known Member

    Messages:
    937
    I forgot about that symptom.

    Yes. Random drop outs too.
     
  13. moefuzz

    moefuzz Active Member

    Messages:
    340
    Location:
    Peeyong Bangyou
    [​IMG]




    Silver encased For Extremely fast transistor?
    ??

    ?


    .
     
  14. slimecity

    slimecity Super Member

    Messages:
    1,732
    Location:
    New Zealand
    OK - progress report -

    I have gone thru and replaced most of the black flags with ceramics and silver micas - I got whatever was in stock for the values I needed.

    I have paused at replacing fuse resistors on the F2778 Regulated power supply board. Note that R's 09-12 are stated as being 1/4W 330ohm fusibles in the SM. I checked them all - they seem to be 560ohm, and dont appear to be the usual colour for being fusibles...... Note also that other places where fusibles are meant to be are just wire links (R's 21, 22 & 61, 62).

    I'm wondering if these R's 9-12 are even fusibles - the ones I pulled all have the values they are marked at. Should I reinstate these in the PCB or replace with new 1/2watt metal oxide 560ohm 1/2 watt types?

    thanks!

    IMG_1534.jpg
     
    Last edited: Oct 7, 2017
  15. Hyperion

    Hyperion Roobarb & Custard Subscriber

    Messages:
    39,475
    Location:
    Hertfordshire, UK
    They don't look like fusibles to me - but now you have them out - you may just as well fit new if you have them on hand. ;)
     
    slimecity likes this.
  16. slimecity

    slimecity Super Member

    Messages:
    1,732
    Location:
    New Zealand
    Yep, cool - it will be easier at least doing that, than trying to stuff those stubby leads back into the holes.

    So thats interesting, if these arent fusibles, that means of the 8 fusibles that the SM says are in the regulated board, there are actually none. In my board anyway. I certainly cant see any other resistors that look like fusibles in that board.
     
  17. Hyperion

    Hyperion Roobarb & Custard Subscriber

    Messages:
    39,475
    Location:
    Hertfordshire, UK
    I didn't see any on that board, I did change a few resistors due to 'glue damage' but as far as I can recall, apart from a couple of value changes (described in my thread) to allow correct setting of the PSU voltages that was all I did resistor-wise on the PSU. ;)
     
    Last edited: Oct 8, 2017
    slimecity likes this.
  18. slimecity

    slimecity Super Member

    Messages:
    1,732
    Location:
    New Zealand
    OK - I'm done with checking for fusibles - replacing the two on the poweramp module boards, replacing all MV12 and VD1212's with 2 x 1N4148, every single bastard black flag has been pulled and replaced with silver mica or the ceramics Hyperion recommended.

    The amp is now back together, apart from extracting the poweramp modules - its actually pretty straightforward pulling this amp apart.....

    Re: safe powering up - will a 100W bulb in the DBT work OK? I ask as I had a Pioneer M22 and I suspect that the inrush current circuit in that amp prevented the amp from ever coming out of protection (ie: it needed more current to do so).

    This X1 also has an inrush current circuit. Would a 100 or 150W bulb be enough to ensure that (if all is well), the amp will come out protection?

    What did others use when testing this amp?
     
    Hyperion likes this.
  19. kevzep

    kevzep Its all about the Music Subscriber

    I powered up the X1 I did on a 120W bulb, it worked fine....
     
  20. slimecity

    slimecity Super Member

    Messages:
    1,732
    Location:
    New Zealand
    Thanks Kev. The big day is Wednesday evening.....
     

Share This Page