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Sansui AU-X11 crowd sourced service manual.

Discussion in 'Exclusively Sansui' started by Ronito6, Oct 18, 2017.

  1. Ronito6

    Ronito6 Super Member

    Procedures and other data - start
    Procedures and other data - end

    The service manual (SM) for the Sansui AU-X11 has eluded my and everyone's (even boffins here in Japan) best efforts to locate.So I think that it is past time that an information collection point be created to accumulate any and all information about the model.

    I will be adding to this crowd sourced point of reference as I report voltage measurements on the X11 that I have that is properly functioning.And I will report on any information I find as I claw my way through Japanese AU-X11 restoration blogs. I will eke out as many new bits of information that is confirm-able in either pictures or second party testing.

    Standard disclaimer:
    All information in this thread is for reporting purposes only and is certainly not an official Sansui statement.

    Valid and test-able corrections welcome

    10/22/2017 Addendum
    I will put all voltage adjustment procedures, and other information like that, here in the first entry of this thread. That way anyone needing that information will know exactly where to find it.

    Who wants to waste time digging through an entire thread for a test point voltage after all.

    ENTRY 1
    Today's new tidbit comes from a Japanese restorer / blogger who calls himself Zyuou2015, and who's X11 restoration can be seen at
    https://blogs.yahoo.co.jp/zyuou2015/14843640.html .

    Among the very well photographed rundown of his X11 restoration we see this...

    ...the X11's Regulated Power Supply Circuit Board voltage measured at TP3 and TP4 are adjusted to 47.5V
    This is the same voltage for the same points as on the AU-X1.


    Let us not forget Nicowico's amazing report on Oct 25, 2015 that AU-X11 equalizer boards
    ( 2 of the 4 boards on the X11 phono motherboard) will also function as EQ boards in an AU-X1.

    Here is the X11 F-3452 EQ board . One of a pair.

    Here is the supplemental service bulletin which lays out the voltage adjustment procedure if you install the pair in an X1.

    Attached Files:

    Last edited: Nov 5, 2017
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  2. Hyperion

    Hyperion Roobarb & Custard Subscriber

    Hertfordshire, UK
    An excellent idea Ron, in one hit this post has expanded the AK knowledge of that model considerably. :thumbsup:
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  3. Ronito6

    Ronito6 Super Member


    More to come. Once I drag both of my X11s out of my storage closet, I will be doing voltage measurements of various points.

    And for best fun...I will take the MM/MC and Equalizer boards out of the dead X11 and install them in my X1.

    What will happen?? I suspect good things.
    Last edited: Oct 18, 2017
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  4. Overundr1

    Overundr1 AK Subscriber Subscriber

    Both of them? Lol, great thread.
  5. smurfer77

    smurfer77 AK Subscriber Subscriber

    San Francisco
    Ronito, great idea and I (i'm sure, we) really appreciate your info in the various AU-X1/X11 threads. I hope to be able to contribute to your thread as I get stuck into my AU-X11s eventually - it's embarrassing, the parts have been sitting there since January. I think all i will add for now is that the parts on on the driver boards, some FET info, and diode info are available in my thread. I will continue the projects shortly, hopefully, and provide more details as I go along.

    Cheers and thanks!
  6. Ronito6

    Ronito6 Super Member

    Your welcome!

    I will, with proper attribution with links, add any data you discover to this thread. As a matter of fact, I will check your thread out this weekend for some tidbits.

    At any rate it's a team effort here . Please add data as you see fit one and all.

    It has just blown me away that even on Japanese restoration blogs and web sites no one has a service manual for the X11.
    I have been looking for years and all I ever see on those sites is either requests for the service manual, or mentions that one does not exist.

    So...that's why this.


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  7. Ronito6

    Ronito6 Super Member

    Side point 1.

    A common X11 fault point on driver board 3460.

    As you can see in this pic from Amp8's site there is a point in the center of the driver board that tends to burn out.
    Pic 1 from http://amp8.com/sansui/x-xx/x11/jpeg/x11-4-4.jpg

    This following pic is from another a Japanese restorer and blogger NicoGuitar http://hoshiinonet.com

    Here is a poor resolution of another burned board from http://www.geocities.jp/tsoka/AU-X11-2.htm

    And last, and most impressively, my 3460 board from my most recent X11 purchase.

    Here is a fixed one from http://minatokobo.exblog.jp/24285599/. Happy endings are the rule.
  8. Ronito6

    Ronito6 Super Member

    An announcement of a small change in how the solid data will be accessed in this X11 effort.

    I will put all voltage adjustment procedures, and other information like that, in the first entry of this thread. That way anyone needing that information will know exactly where to find it.

    Who wants to waste time digging through an entire thread for a test point voltage after all.
    Last edited: Oct 22, 2017
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  9. smurfer77

    smurfer77 AK Subscriber Subscriber

    San Francisco
    yeah I think that is a good idea. I did that for another thread of mine on a different model; in that case I was summarizing all of the difference between service manual and my amp, but does seem convenient to have it all in the first post summarized. Good idea!
  10. Ronito6

    Ronito6 Super Member

    I will update this weekend.

    I will add some notes on all possible test point voltage measurements from my good X11 and note the process of taking those measurements.

    I will also present a rewritten version of the service addendum pictured in the first entry of this thread.
    It will be a more legible and instructive copy of that document.

    More soon.
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  11. Ronito6

    Ronito6 Super Member

    I've checked nearly all voltages and I can confirm that many of the voltages and adjustment procedures for the X11 are the same as in the X1.

    Setting the voltages of the driver cards was tricky.

    A relay was slow to connect so the voltage measured near 0 at the card's voltage test point. I waited patiently and slowly turned the volume knobs up until I heard a relay click in.
    I then turned the volume back to minimum and the voltages on the driver cards were nearer to normal. Low but adjustable. 16.5 mv right driver and 13.6 left.

    Since an official voltage number for the driver boards still eludes me I set both cards to 20mv.
    The X1 driver cards use 25mv so I thought 20 was a safe choice for my X11.

    The only mystery is dialing in the F-3451 and F-3452 EQ cards.
    The instruction for the procedure is, "...connect the negative probe to ground, then connect the positive probe to test point 1 (TP-1)..."

    I am not certain if that ground is chassis ground, or a ground point directly on the card being measured and adjusted.

    So until I can get some advice, the following will be just for fun. Until I am 100% certain please consider the following "INSTRUCTIONS" an early draft.
    (The illustration is certainly 100% OK so I will add it the my first posting too. Once again, that first posting is where I will put all 100% good information)

    More tomorrow as it is rather late here now.



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  12. SanthoshA

    SanthoshA Active Member

    First of all thanks for putting up this thread, it is very useful for me and the rest who owns an AU-X11.

    I think if we can trace the ground pin behind the speaker terminals and see where it goes we will know if it makes a difference between using the chassis ground and the ground pin in the rear.
    In case they are all wired to the same location, grounded to the chassis then we would not have to bother about it . I will also see if i can do it when i have some free some time and will update back.

    I had this same question when i went through the AU-X1's service manual.
    And how do we actual derive the bias voltage required for the transistors idle state.

    I have seen in a thread the voltage's were calculated with reference to current drawn by the X1, and we used the same current draw to arrive at 11mv bias for the AU-X11.
    Is it possible to measure this using an oscilloscope to check whether the 11mv keeps the transistors in the active region or we need a higher bias voltage.
    I was thinking if some one has good measurement equipment we do a run with say, 0mv bias and slowly increase it and check if there's a wave form change, and then probably decide the right bias voltage required.
    The wave form will not be perfect if the transistors are not in their perfect idle state right ?
    I also noted that the bias voltage stays in the set value across test points, say when i increase the preamp volume by minimal amounts, till then the bias voltage remains at the fixed value.
    Can this be possible at-least, i am not sure but just have this thought pondering over my mind.
    In case my assumption is wrong please correct me.

    This is just a thought process and i am not a good techie or a service engineer as the rest of you guys. I am basically one of the X-11 owners, hoping to keep it in good shape and extract its full potential, with some insight in electronics, and of course this amplifier is complicated.

    Any small bits and pieces of information shared of the X11 is of great value to me.
    Thanks again @Ronito6
    Last edited: Nov 6, 2017
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  13. smurfer77

    smurfer77 AK Subscriber Subscriber

    San Francisco
    A ground point on the card/pcb, rear ground connector, or any other ground on the amp such as at the ground terminal of the power supply caps, should be the same voltage. if not, you have a problem.
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  14. Ronito6

    Ronito6 Super Member

    This is a great way forward you've suggested here. Sadly beyond my humble abilities at the moment, but likely an issue that will be tackled by a super-tech here sometime in the next 12 months.

    Although 20mv is working for my drivers I will crank my driver cards back to 11mv as the measurements of 16.5 mv right driver and 13.6 left rather suggest that you and Smurfer77 are closer to the truth.

    In Smurfer77's posting (entry 17, in his thread http://audiokarma.org/forums/index.php?threads/sansui-au-x11-repair-and-restoration.734874/ ):
    "...but the AU-XII has 0.22 Ohm emitter resistors on the power transistors so one would more likely want to use ~11 mV (assuming ~50mA idle is the target, or maybe 16 mV or so if you shoot for 75 mA.)"

    But he adds in an edit to the same posting in the same thread:
    "EDIT: note that output bias current I mention in this post is 2x too large, because I didn't realize at this time that the AU-X1/AU-XII bias test points are over two emitter resistors, instead of one. So what I said about taking care setting bias voltage according to AU-XI manual because of AU-XII emitter resistor values being different stands. The target voltage I mentioned stands. But the resultant current would be more like 25mA, or so instead of 50mA mentioned in post below."

    So 11mv it is...for me.

    SanthoshA, I forgot if your X11 was working well enough to do a voltage measurement of the drivers? If so what were your results?

    EDIT: Never mind. I went to your (SanthoshA's) X11 thread and found that you also have come to the conclusion that 11mv is likely the safe voltage for the drivers.

    Until a test as you suggested is done to prove the extrapolation, 11mv will be the target for voltage for the drivers. I will add it to the information in the first entry with an asterisk to denote a final testing or outside confirmation is pending.
    Last edited: Nov 6, 2017
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  15. SanthoshA

    SanthoshA Active Member

    I would also like to add on to this topic regarding couple of other points as well.
    Bias Adjustments: They fluctuate based on temperate changes and also based on your power supply voltage the voltage from the mains, in India where i am based out of there is a huge fluctuation in voltage, in my mains, and each day the measurement i make changes slightly or so. I have a stabilizer but it is not servo based. I feel temperature in which bias is adjusted makes a big difference too, say if i have my fan on the bias voltage when set at 11mv, it starts dropping to 8mv, and then when i turn it off it rises to 11mv. Just an observation though, i felt the temperate plays a vital role.

    When i first measured bias in the X11, the right board would keep increasing above 30mv, and then a relay or a clicking sound occurs and the bias drops to 25mv.
    The left side board when i measured was at 25mv idle and constant, another key point in this topic is the outputs used for the X1, i believe they are the Sanken Output's and there are 6 of them at each side driver boards. In our case with the X11, they are based on the Sansui NMA/NMC outputs.
    Right now we are arriving at the bias voltage based on the current drawn, by the X1, but then what if the change in outputs to Sansui NMA/NMC in the X11, will make a change or will it consider a different current draw, which could/may be different from the X1. Is there a calculation used to derive the bias voltage based on emitter resistors alone, or can the current drawn be calculated from the specs of the transistors. The other easy way to justify this will be to perform the oscilloscope check for wave form changes based on bias voltages set, but i don't have the equipment or neither the technical expertise to check this out.

    When i went though your post, i noted that one side of your driver board was at 25mv same as my left side driver board which was constant at 25mv, assuming my right side driver board, is defective some where, i would say we both had a evenly matched value of 25mv atleast in one of our boards. And as i have also mentioned in my post, the right side speaker section, has a 0.5v drop in the voltage at speaker terminals with a sine applied, some times the differences are even 1volt. The left though seems steady and perfect.
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  16. SanthoshA

    SanthoshA Active Member

    Ok, here are couple of other findings for bias voltage determination.
    When i checked the AU-X1 service manual again, i see the below resistors are indeed in a parallel connection, and the voltage 20mv is determined across these 4 resistors alone.
    R714 and R716,R718 and R720.
    X1 Parallel Resistance.jpg

    RNet1 = Resistance sum of R714 and R716 adds upto 0.66 ohms.
    RNet2 = Resistance sum of R718 and R720 adds upto 0.66 ohms.

    There two values are in parallel to the bias test point , so effective net resistance value adds up to the following.
    1/Rnet1 + 1/Rnet2 = 1/TotalR

    Arriving at a total resistance value of 0.33 ohms across bias point for the AU-X1.
    Net Current = 60.6ma with 20mv voltage ( as per schematics )
    Net Current = 75.75ma with 25mv voltage ( as per adjustment procedure )

    X11 Voltage:
    Voltage(considering X1 schematics) = 13.3mv
    Voltage(considering X1 adj.proc) = 16.6mv

    If they are indeed wired in parallel, the above values will be correct.

    Can some please help me verify the findings?
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  17. smurfer77

    smurfer77 AK Subscriber Subscriber

    San Francisco
    R714/R716 are not in parallel to R718/720. Yes, they are joined in the middle, but the other ends go to different places; to calculate the current through R714 and R716 you need only be concerned with the resistance and voltages of those two resistors.
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  18. SanthoshA

    SanthoshA Active Member

    Yes you are correct , I somehow missed it.
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  19. Ronito6

    Ronito6 Super Member

    The next step for me is to once again try the EQ card voltage adjustment procedure laid out in the instructions copied from Nicowico's supplement.

    My first try did not seem to work properly. I grounded TP-2 to measure and adjust voltages at TP-1.
    I used chassis ground. I think I missed something as the measurements were too wild.

    My chassis ground point did turn out to be a bit loose, but it worked OK for the other measurements.

    I will give it another whirl soon.

    Relays and the condition of controls play a bigger role in the X11 than the X1. The relays must engage to make the test point measurable.

    The weak condition of either my small signal relays, or volume controls, result in my needing to turn up the volume controls a little bit until I hear relays engage. Turning down the controls to 0 / minimum after that, the relays remain on.

    Now a report about the X11's voltage values that I could measure, how I did it, and the results.

    Basically the X11 uses the same procedures and test points for the X1. (Except for the EQ boards.)

    The F-3463 board is divided into 4 areas, and it sends power to the 4 cards that populate the phono motherboard. Areas 1 and 2 send power to the head amp boards F-3449 and F-3450. And areas 3 and 4 send power to the F-3451 and F-3452 EQ boards

    Voltages on areas 1 and 2 surprised me. The initial check found areas that those areas were measuring only 9.10v and could not be dialed beyond 10.20v. I adjusted them to 9.25v. The SM for the X1 says that those equivalent areas should be 10.5v, but is it the same for the X11? I suspect it should be.
    (iVR-1 measured between chassis ground and TP-1. iVR-2 measured between chassis ground and TP-2.)

    But voltages on areas 3 and 4 of the F-3463 were nearly exactly 47.5v on initial check and were easily dialed to 47.5v.
    The X1 requires the same voltage in those same areas.
    (iVR-3 measured between chassis ground and TP-3. iVR-4 measured between chassis ground and TP-4.)

    DC offset for the F-3460 driver boards is ok and can be set to zero.
    (Respectively, F-3460 voltage is adjusted using iVR-1 and is measured at speaker terminals)

    Bias for the F-3460 driver boards can be measured at the topside test point.
    Although I initially adjusted voltage to 20mv, it will soon be changed to 11mv.
    (Respectively, F-3460 voltage is adjusted using iVR-2 and is measured at the topside test point. I assume it is intended to be indicated as TP-1 in the non-existent X11 SM, but I found no markings on the PCB upon removing that header to see if it was so marked.)

    HEAD AMP BOARDS F-3449 and F-3450
    No problems. Initial measurements saw both boards under 2mv out of spec. Dialed to 0mv.
    (Respectively, F-3449 and F-3450 voltage is adjusted using iVR-1 and measured between chassis ground and TP-1)

    EQ BOARDS F-3451 and F-3452

    This board is divided into two sections, left channel and right channel.
    No problems. Initial measurements saw both boards around 6mv out of spec. Dialed to 0mv.
    (F-3455 voltage is adjusted using each channel's iVR-1 and measured between chassis ground and each channel'sTP-1)

    That is it for now.

    Seems to me that, to no surprise, the X1 service manual is a pretty good guide for voltage adjustments.
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  20. Ronito6

    Ronito6 Super Member

    Well, a quick addition.

    I decided to ask the guys at Aqua Audio Lab up near Tokyo if a service manual for the AU-X11 ever existed.

    (ICYDK: Aqua Audio Lab is an audio electronics repair shop that specializes in servicing Sansui's.

    It took 48 hours for them to reply, but they replied.
    And they said:
    Servos (Service) manual AU-X11 existed. I do not have.

    So the good news is...
    there was a service manual created for the X11.

    The bad news is...
    not even one of the leading Sansui maintenance shops still around has one.

    Well, this effort continues. More soon.
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