Sansui AU-G99X, a little help needed.

Discussion in 'Exclusively Sansui' started by bharry, Jan 8, 2019.

  1. bharry

    bharry AK Subscriber Subscriber

    Messages:
    58
    Just traded for a Sansui AU-G99X this past weekend and I am impressed. I hooked it up to my Ohm Walsh 3XO and it is like I am listening to them for the first time, they are finally getting the power that they need.

    My issue is that when I hooked it up everything worked fine for a day but when I was listening to an album the next day the left channel went quiet. The issue is only with the phono input, all the other inputs work fine. I switched out the turntable and got the same results with the other table. Toggeling between MM & MC doesn't make a difference. It was on MC (Denon DL-110) when the problem occurred. I'm not sure where to start. I'm not a complete newbie, I fixed up a AU-555a by replacing all the UFO transistors and got it working again, but I'm still a bit lost..

    Luckily I've got an external phono preamp to use for now but I'd prefer to use the built in one because it sounded so good.

    I downloaded the serivce manual but it hasn't been much of a help yet.

    Thanks in advance for any help!

    [​IMG]
     

     

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  2. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    Location:
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    It might be dirty contacts on the Phono input selector switch 'S2' (MM/MC) - and/or the Input selector switch S4 (push buttons) as the Phono signal is routed via this switch group before passing onward to the rest of the amplifier. A squirt of DeOxit on the contacts and a bit of exercising of the respective switch should bring it back if this is the case.

    NB: I am assuming that the amplifier plays ok on all other inputs...

    Take a look at the schematic - where the signal path is clearly indicated, check things along this path to find the issue.
     
  3. stopkidding

    stopkidding Well-Known Member

    Messages:
    537
    I used to have the same problem with my G99X in the past. A nice whack on the right side of the Amplifier would temporarily fix it. It was due to cold solder joints. Wouldn't hurt to reflow the joints on the phono board if deoxit doesn't fix it.
     
  4. bharry

    bharry AK Subscriber Subscriber

    Messages:
    58
    I tried the quick and easy Deoxit option but it didn't work. I'm going to have to take a look at the phono board next but I have to admit I'm a little intimidated, it is tight in there.
     
  5. delboyko

    delboyko New Member

    Messages:
    31
    Location:
    Croatia
    Yup, you'll have to unscrew the right side plate, unplug some of the cables going into PCBs mounted on the right (a bunch of them so take pictures and mark them) and then you can pull the right side from the frame. Consider your self lucky cause It's the easiest side panel to pull from this amp. :)

    Try wiggling the input cable from the back. It might be cold solder on the input board as well.

    The phono board is mounted with a few plastic pins to the side, and 2 screws on the front plate(got to remove the faceplate (easy)), and also a few screws holding input board to the back. After this you're ready to go. Resolder everything and reassemble.
    Here's a pic just to get the feel.

    [​IMG]
     
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  6. bharry

    bharry AK Subscriber Subscriber

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    Anything look bad on this board?
    [​IMG]
     

     

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  7. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    Looks ok to me, the picture is beautiful quality for seeing soldering defects.:thumbsup:
     
  8. bharry

    bharry AK Subscriber Subscriber

    Messages:
    58
    I very carefully hit everything with the soldering iron to reflow everything. I was very careful to not overdue it. Hooked it all back up and I'm still only getting sound out of one channel on phono.

    Anything else I can try?
     
  9. delboyko

    delboyko New Member

    Messages:
    31
    Location:
    Croatia
    Did you try input selector board?
     
  10. bharry

    bharry AK Subscriber Subscriber

    Messages:
    58
    Not yet, I have to figure out how to access it first. I'm hoping the front face falls forward like the side did.
     
  11. delboyko

    delboyko New Member

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    Location:
    Croatia
    I meant input terminal board, sorry for misleading you. It's on the same side plate as phono board.
     

     

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  12. bharry

    bharry AK Subscriber Subscriber

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    No problem. I did try that last night but just specifically the phono section, nothing else on the board.
     
  13. delboyko

    delboyko New Member

    Messages:
    31
    Location:
    Croatia
    Well, then the problem might be harder to find than assumed. I'm starting to think the problem isn't in cold solder. It might be an open cap on phono board after all.

    You could try wiggling the cables a bit with phono input playing with the top lid opened, just be careful of course. :)
     
  14. bharry

    bharry AK Subscriber Subscriber

    Messages:
    58
    I think I'm going to put it all back together and bring it to a local tech here in Rhode Island. Turnaround is usually a week or two and the prices are reasonable. It's getting to be a little more complicated than I can handle at this point and this amp is too nice for me to screw it up.

    Thanks for the help everyone!
     
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  15. bharry

    bharry AK Subscriber Subscriber

    Messages:
    58
    Just dropped it off at Stereo Discount Center in East Providence, RI.

    I already miss it. I'll update the thread with what the problem was when I get it back.
     

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