AU-X11 reconditioning

Discussion in 'Exclusively Sansui' started by Hyperion, Mar 16, 2018.

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  1. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    I have a JDM AU-X11 on the bench from another AK member for reconditioning. I have just about managed to correct the mistakes of the (Japanese) complete and utter numpty who worked on it before, it now works as intended. So the rest should be plain sailing, given that there is NO schematic and NO service manual to be found anywhere.

    I have already had some excellent support from AK member @SanthoshA with information to assist me in correcting the mistakes, thank you Santhosh. ;)

    I really like the improvements on the internal construction as compared to the AU-X1.

    I'll post here if I find anything of note.
     
    Last edited: Mar 16, 2018

     

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  2. Overundr1

    Overundr1 AK Subscriber Subscriber

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    Oh come onnnnn, post everything noteful or not, been a slow week in photo's and the AU-X11 is one unit most of us will never get our hands on. :)
    -Lee
     
    Last edited: Mar 16, 2018
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  3. kevzep

    kevzep Its all about the Music Subscriber

    Yep, pics or it didn't happen....:biggrin:
     
  4. Hipocrates

    Hipocrates Anti-Muppet Subscriber

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  5. BLAH BLAH

    BLAH BLAH AK Subscriber Subscriber

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  6. Overundr1

    Overundr1 AK Subscriber Subscriber

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    For extra credit please include the action shot of this for those of us with devious mindsets lol ------

    "complete and utter numpty"

    for some reason it reminds me of that old nursery rhyme :)

    -Lee
     

     

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  7. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    Unfortunately time has passed and I am unable to show you all how it was originally, thankfully however I have been able to erase almost all traces of the deeds of the 'numpty'. :)

    But I could explain what I think he(she?) did, and my guesses as to 'why'. ;)
     
    Last edited: Mar 17, 2018
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  8. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    The story starts with the X11's original owner (in Japan) listening to some music, there is a 'pop' and it loses a channel. Sounds pretty serious, but it does still power-on and looks and seems normal apart from the missing channel. Somehow it gets sold on Rinkya, and the new owner is a UK based AK member, who passes it directly to me for attention.

    I'm going to guess here that either the (Japanese) owner, or possibly some numpty from a (Japanese) repair shop tried to fix the fault. When I inspect the inside of the amplifier I can see one new capacitor on the Power/Protection board, a UB152 bridge rectifier squashed right down onto the board with all the leads bunched up together. And almost all of the screened leads going to the upper group of rear panel RCA connectors (MM/MC, Tuner, AUX) have been untidily de-soldered.

    Some of the rear panel RCA connectors on the X1/X11 are special 'shorting connectors' to stop extraneous input noise entering the amplifier - so only when they have a cable plugged in are they non-shorting. Just a guess, but I think this is what confused the numpty, I am guessing that as he found he had shorts across the input connectors, he assumed that they must be wired incorrectly :no: - or something? - anyway he removed most of the connections and started putting them back with the screen and inner transposed.:yikes: but stopped after he had done 2 - and must have decided the amplifier was too broken?

    The squashed bridge rectifier had small explosion marks on at least two of the leads, (DC side shorted), tested and found it was 'open'. In trying to understand the above, initially I misidentified the bridge rectifier as being for the +/- 11V supply to one the MC Head Amps, possibly explaining the disconnected RCA sockets? :dunno: anyway I have now realised that it was for one of the +/- 47V low current supplies for one of the Power Amps. So I begin to tidy up the solder on the RCA connector PCB and find that the connector board has been snapped in half ! - whoever worked on it before can't have realised that you need to remove 4 screws (not 2) to release the RCA connector board containing 2 separate groups of RCA connectors. I noticed he thoughtfully :rolleyes: filed the snapped edges of the PCB, which means there is now a gap between the 2 pieces of board when mounted - making it much more difficult to repair. :( thankfully there are no disconnected/damaged tracks). I'll be leaving it like that, as the 2 groups of connectors still have 2 securing screws each which I think is good enough.

    So I ask AK member SanthoshA for a picture of his RCA connector wiring which he kindly and quickly provided. I remount the now '2' RCA boards, and re-wire the connections. I replace the bridge rectifier, and I note that the soldering on the single replaced capacitor I mentioned was neatly done. The usual round of short circuit checks (all OP transistors are OK, drivers look fine too), and I am ready to power up for the first time via DBT and step down transformer.

    It powers on fine, DC offset is fine, Bias current adjusts and although 'drifty' is predictable and as I would expect. After checking the bias and leaving it on for about ½ hour I can see no problems. I powered it up on full mains, all rails present and correct, a reset of bias and DC offset checks OK. Subsequent listening checks reveal that the amplifier is OK (both channels!) - it sounds tired, not nearly as nice as my AU-X1 - but there is a touch of class shining through nevertheless.

    So, now I am now going to restore this beauty.

    There is already an excellent live X11 reconditioning thread, so I won't bother to post mine here - maybe a few pictures at the end.
     
    Last edited: Apr 17, 2018
  9. Overundr1

    Overundr1 AK Subscriber Subscriber

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    Great read thank you. It will be interesting to hear your opinion about the AU-X11 vrs your AU-919 once you finish the rebuild and if it would unseat the 919 from king of the hill status.
    -Lee
     
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  10. Fredrik 1977

    Fredrik 1977 Super Member

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  11. Ronito6

    Ronito6 Super Member

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  12. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    The latest is that I have now completed the following:

    2 x MC Head Amps.
    2 x MM Head Amps.
    1 x Driver Board (almost) - completion of first one halted by back ordered parts shipping on 11 April according to Mouser.
    1 x Muting/PSU Board. (F-3454)
    1 x Phono Mother Board.
    1 x Main Regulated PSU - in progress now.

    There still seems to be a mountain of work to do, but thankfully the 'Sansui Glue' is only present in tiny amounts.

    To Do:-
    Flat Amp Board. (Control)
    PSU/Protector Board.
    1 x Driver Board and other one to completion.
    Interface Board. (+1 relay)
    Speaker Relays.
    Speaker Terminals.

    The signal relays nearly drove me nuts, this time I used insulated wire, so that means 8 wires & 16 joints per relay, and 9 relays - I have now done 8 of them. :)

    And the good news is - thanks to Ron (Ronito6) I now have a partial Service Manual - with a lot of work done by Ron to get it into usable condition, thank you so much Ron. ;)
     
    Last edited: Apr 17, 2018
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  13. Ronito6

    Ronito6 Super Member

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    I live to give. (And for Stan’s Doughnuts)

    What relays are you using?

    Also I am looking forward to your applying the voltage adjustment procedures I translated. I’m hoping you can confirm that my work is accurate.

    The document is still a work in progress until a real EE guy can confirm the validity of my writing.

    The X11 and the X1 are so close that the Japanese version of the X11’s voltage adjust procedure page uses literally the very same illustration which was used in the X1 service manual. The board illustration even retains the label F-2778, just as it was labeled in the X1’s SM. The X11 SM should have re-labeled the illustration “for F-3463”.

    The biggest difference I see between the X11 and the X1 is the incorporation of a counter signal circuitry. So the X11 has twice the trimmers on certain boards than the X1.
    (Both driver boards, both phono boards and both EQ boards to be exact.)

    Well...here’s hoping my translation proves correct.

    Finally, Santhosh helped A LOT in getting this voltage procedure translation started. He kind of put the fire under my ass to see it through. So credit to Santhosh. I seriously would not have started or finished the translation without his initial translation work. (He was rather motivated.) CREDIT TO SANTHOSH.

    Ron
     
    Last edited: Mar 28, 2018
  14. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    Last edited: Mar 29, 2018
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  15. AFK81

    AFK81 New Member

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    Good luck with the build.
    Any write up on the X11,is like watching an action movie.:rockon:
     
  16. Ronito6

    Ronito6 Super Member

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    [​IMG]
     
    Last edited: Mar 30, 2018
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  17. Overundr1

    Overundr1 AK Subscriber Subscriber

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    Snip ---
    'The signal relays nearly drove me nuts, this time I used insulated wire, so that means 8 wires & 16 joints per relay, and 9 relays - I have now done 8 of them. '

    My eyes would be toast after that many small connections, well done. Would rather fix pass throughs than wire that many relays :)
     
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  18. Overundr1

    Overundr1 AK Subscriber Subscriber

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    Goes without saying that you used only the finest decorator color choices for those wires :D
     
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  19. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    Well, red for the coil and black for the contacts, nothing too 'jarring' to the eyes. :)

    I measured the resistance of all the contacts on the old relays, and found one which was high resistance (~50Ω) which varied randomly if you tapped it. ;)
     
    Last edited: Mar 31, 2018
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  20. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    A couple of pictures for your viewing enjoyment :)

    Here is a picture of the rebuilt regulated PSU - note the use of 'short & fat' electrolytics where possible for best airflow around those heatsinks. 4 trimmers & 4 zener diodes replaced - (so I could raise them up on ceramic beads), all electrolytics replaced, all dual diodes replaced. Ceramic capacitors and all other semiconductors left alone, aside from all the heatsinks & power transistors being removed for cleaning and re-application of heatsink compound. The only Sansui glue present was a small blob against each one of the 4 foreground electrolytics on the right hand side of the view below.
    IMG_2335a.jpg

    And a picture from the other side - showing the where the dual power resistors (½W & 2W) have been replaced with single 3W power resistors (i.e. the 8 white things). I re-used the stock sleeving which was essential for the old ones due to the exposed two resistor 'middle joint', I thought it might be a good idea to protect any wiring in the area from the heat.
    IMG_2336b.jpg
     
    Last edited: Apr 11, 2018

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