Sansui XR-Q7 issues

Discussion in 'Exclusively Sansui' started by Ryan_1993, Jan 10, 2019.

  1. Ryan_1993

    Ryan_1993 New Member

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    Hi all,

    I got a Sansui XR-Q7 from a friend of a friend a couple of days ago, he got given it from a family friend, but didn't want it. It had a weird male kettle lead plug on it so he didn't test it, so I've wired it up with a normal UK 3 pin plug.

    It powers on, but it doesn't seem to operate at all. When you press start/stop nothing happens, other than the motor for the tonearm starts spinning, the belt on this looks okay. The tone arm doesn't lift or anything either. If you manually place the tone arm on the platter and press start stop all it wants to do is return to the resting point no platter spin.

    I've looked a bit online, but with it being quite a rare model its hard to find details. A few on a few Sansui audio groups have said it almost certainly sounds like bad caps, a sensor out of whack or a PSU issue or a combination of all three. Definitely seems like an electronic issue to be honest to me.

    I’m taking it to a repair tech over the weekend. I think my biggest concern is if its an issue with one of the turntables main intergrated circuits. Which I doubt then could ever be fixed?

    Here is a video


    It does look a fantastic TT though and will be a welcome upgrade from my Pioneer PL-12D

    [​IMG]

    [​IMG]
     
    Last edited: Jan 10, 2019

     

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  2. Ryan_1993

    Ryan_1993 New Member

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    Does anyone have any thoughts or similar issues with their Sanusi TT's?
     
  3. Balifly

    Balifly Listening Subscriber

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    How did you check the belt condition ? :idea:

    How long is the belt you are referring to? :idea:
     
  4. Ryan_1993

    Ryan_1993 New Member

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    The belt drives the tone arm mechanism. I just checked it was nice and tight and still gripped properly. I held the main white Nylon drive cog and noticed that the belt still had enough grip in it to stop the motor spinning as well, so I don’t think the belt is slipping. if this were the case you’d expect the motor to still be running past a loose belt.
     
  5. Sansuiman

    Sansuiman Well-Known Member

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    560
    Location:
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    The XR-Q7 shares much of the design of the automatic tone arm mechanism with the XR-Q9 and XR-Q11 models. I own a few of the latter two - not the Q7 - and they all exhibit this same problem you are describing. I've never yet nailed down exactly what is wrong, though there is a mechanically complex system in play underneath the tone arm (inside the plinth) to cue and rotate the tone arm via a clutch unit and solenoid all of which is under microprocessor control.

    The MCU is a Sansui custom chip by NEC (uPD series chip with embedded program ROM) and I have been leaning towards suspecting it may be at fault since the mechanism relies on several time-critical signals at various I/O ports that have to occur in exact sequence to control the solenoid and small DC motor that drives the clutch via a small belt.

    On the mechanical side, the clutch is comprised of plastic (appear to be nylon or some such) friction plates with a sqaure cut rubber tire sandwiched in between. The solenoid is employed to close the gap between the friction plates thereby causing the tire to grab the inner surface of the fixed friction plate and rotate the tone arm.

    Part of this assembly also incorporates a cam. At a certain point in the rotation, said cam raises and lowers the tone arm rest so that the arm is elevated when traveling from the resting position to the lead in of the record, then gently falls back into play position. The cue button is supposed to manually trigger the lifting and lowering of the tone arm via the same mechanism.

    So far, despite much tinkering, I've not gotten one out of 6 (4 of the Q9 and 2 Q11) such units I have here working. I have other working turntables, so it hasn't been a big priority since day to day responsibilities interfere with committing the time needed to really troubleshoot it in detail. I would, of course, like to get them working. They are very nice looking units and by all accounts sound very good. Certainly an advanced design, and the specs - and list priice - bear out that much effort went towards making them high end units, insofar as Sansui made high end tables.

    I'll be interested to hear what your tech determines, if anything. Please do post here if he finds a solution, as I and a few others have kicked these around trying to get them working for years now. So far, a solution has been elusive.
     
  6. Ryan_1993

    Ryan_1993 New Member

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    This has me slightly concerned now. I assume there would be no way to bybass the MCU and just make it operate as a manual Turntable instead and bypass the tonearm mechanism completely too? I would be happy with that as a last resort if it couldn’t be fixed properly.

    What was the list price of the Q7 BTW. I can’t find much information online
     
    Last edited: Jan 10, 2019

     

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  7. Sansuiman

    Sansuiman Well-Known Member

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    On the Q9 and Q11, there is a harness that can be unplugged from the one circuit board that effectively disables the automatic "computer" functions, and renders it a manually operable unit. Been quite a while since I messed with one now, so will need to dig one out of storage and check to see which connector was the one to pull. Of course, I don't know if the Q7 follows the same exact design intenrally as the upper two models, but suspect they are largely similar in layout and internal components.

    The Q11 added an optical sensor on the hesdshell that could "read" the gaps between tracks on an LP and one could program (ala a CD player) the tracks to be played, skipping any others automatically. On the order of the old BSR accutrac units, but in a much better table.

    Looks like list price for the Q7 was $499, Q11 (both per the Orion audio blue book) was $680. Once I dig one out and take a look, I'll post the connector to pull for manual operation.
     
  8. Balifly

    Balifly Listening Subscriber

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    Tried several belts until I was able to find one with the correct tension and lifted the tone arm of my turn table.

    The old grease did not seem to be much of a hindrance, put I have it cleaned and relub with new lubricant during the process.

    So my efforts to rehab the turn table may have had many contributing factors, don't know which was the most crucial.

    Incidentally, Sansui parts had the clutch mechanism for sale about two years ago and I bought only two for my XR-9 at the time.

    I still have the spare in the basement, if I can locate it I will try to take some close up picture of the pieces for "the record". :idea:
     
  9. Ryan_1993

    Ryan_1993 New Member

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    I've been looking at my service manual, do we know what the "uPD series chip with embedded program ROM" is called in regards to its specific part number? I've had a quick look on my board and I don't see anything NEC Branded on mine. I have Toshiba chips and a couple of small unbranded ones and having searching several part numbers from the service manual they actually seem to be widely available online.

    Fingers crossed even if it is an IC issue then it looks like it might be fixable.
     
  10. Sansuiman

    Sansuiman Well-Known Member

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    The chip in question, if I recall correctly, is a 40 pin DIP, marked with the Sansui logo, and an NEC part number - uPD something - will look when I get one out. I know the Q9 and Q11 each used a different variant, due to added functions implemented on the Q11.

    No idea if the same type of MCU was used I the Q7, though given its functional similarity to the Q9, I'd have expected it to.

    Balifly, do 8ninfer correctly from your post that you got one working correctly again? It reads that way to me.
     
  11. Balifly

    Balifly Listening Subscriber

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    Yes, that is correct.

    XR-9 is working, only need the belt re-installed. :)
     

     

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  12. Qsiris

    Qsiris Active Member

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    My Q7 developed similar erratic behavior 2 years ago. After some troubleshooting I came to conclusion that
    problem is mechanical-electrical. Logic IC doesnt get correct sequence of signal inputs and reacts in a nonsensical way.
    It would be a great fix to just unplug a connector and force manual mode. I would definitely take my Q7 out of a closet. :)

    On a side note I love your Akai RtR . What model is it ?
     
  13. stopkidding

    stopkidding AK Subscriber Subscriber

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    If the motor starts spinning and then the tonearm goes nowhere and dies, then it may the automatic mechanism. I have a XR-Q5 and had the same issues. So I just ripped out the entire automatic tonearm mechanism. Now it plays beautifully as a full manual. It totally reliable this way.
     
  14. stopkidding

    stopkidding AK Subscriber Subscriber

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    Here are some pictures
     

    Attached Files:

  15. Ryan_1993

    Ryan_1993 New Member

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    My platter doesn’t even spin up and can’t get it to. I don’t think the motor is bad though from reading it seems that if the motor-board control isn’t getting the right voltage either through bad caps or out of whack sensor or whatever, that it won’t be triggered to start up apparently.

    All it does when powered on is the tomnearm wants to return to the rest position and nothing more.
     
  16. Ryan_1993

    Ryan_1993 New Member

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    Thanks Its an Akai GX-4000D
     

     

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  17. Ryan_1993

    Ryan_1993 New Member

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    Had another look the only “UP” thing I can see in the service guide under IC’s is something called a upC78M05H which turns out to just be an NEC voltage regulator and equivalents are available online.
     
  18. Sansuiman

    Sansuiman Well-Known Member

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    Just realized - I hadn't watched the video in the OP earlier - that the tone arm is moving back to home position. So, it's doing more than the Q9 and Q11's I have here. The 9 and 11 have a green LED marked "computer" which is supposed to illuminate when the MCU is carrying out some operation. Under the failure these units have, the computer LED blinks at attempted startup (while failing to cue and move the tone arm into position) for some period of time, then the unit becomes non-responsive unless powered off and back on again. The platter will spin at the selected speed for a bit, but then will stop when the computer times-out.

    So, the failure of the Q7 under discussion is a bit different than that I've run across on the 9 and 11 models. I also note the 7 does not have the computer indicator on the control panel. Perhaps there is greater design difference between the models than I had presumed. Moreover, the internal pictures of the Q5 posted upthread reveal it is quite a bit different in overall design than the 9 or 11.

    I'll try to get one of my 9's out tomorrow after work and provide some additional details. However, if the 7 is much different inside, then what I find may not be all that helpful. More to come.
     
  19. Ryan_1993

    Ryan_1993 New Member

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    Thanks yeah the two lights it has are quartz locked and syncro locked. Neither of these light up, which isn’t unexpected since the motor doesn’t turn. No computer light or anything on this model.

    Thanks
     
  20. Ryan_1993

    Ryan_1993 New Member

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    So I dropped off the turntable to my repair tech yesterday. He’s going to look at it over the coming week.

    My Fingers are crossed that it isn’t any kind of unfixable IC issue lol.
     
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