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G9000DB Balance pot is seized?

Discussion in 'Exclusively Sansui' started by Zeke, Dec 7, 2018 at 1:40 PM.

  1. Zeke

    Zeke Demi-God of Brilliant BS!

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    Location:
    Lewiston, ID
    1. This is weird.
    2. I have no idea what happened?

    For years, my Audio Muting switch (occasionally engaged for low level listening) has caused an imbalance requiring a turn on the left/right adjustment to center. So, I've likely used this pot more than most. This morning, when brought back to center? It just FROZE. There's no discernible impact on sound -- thankfully it seized centered for normal play -- but this seems quite odd?

    I'm fighting the urge to really torque and "break it loose" but I'm reasonably certain that's a bad idea and I should just leave it alone?
     

     

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  2. Sansuiman

    Sansuiman Active Member

    Messages:
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    This pot has a detent (click) at dead center, and the portion of mechanism that creates the detent may be the issue. May also be one of the wipers internally broke loose and has jammed the travel, but I'd not think that would create much resistance against movement. Morever, if one of the wipers wasn't tracking correctly, you'd not have balanced audio right now.

    Whatever you do, don't force it, as that is virtually guaranteed to break it and cause the unit to be unusable barring replacement of the pot. I'm sure others will chime in here. It may be possible to disassemble this pot to do repairs but it isn't one I've personally been into yet.
     
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  3. kevzep

    kevzep Its all about the Music Subscriber

    They are just a cheap pot, one of the "why did they do that?" things about the G9000.
    You are going to have to remove it from the unit which will mean taking the faceplate off, once you are in this far then its pretty easy from there.
    You undo the nuts from the pots and remove the PCB assembly which the balance pot is soldered to. Then you can assess the situation from there.

    If you are having problems with the switches, you are going to have to remove them, dismantle and clean them, remove all the black tarnish which builds up over the years.
    Its not good enough these days with the age these units are to just squirt contact cleaner in them from the outside.
     
  4. Hipocrates

    Hipocrates Anti-Muppet Subscriber

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    Maybe something stock here

    CIMG0202.JPG

    And the wafer will look like this

    CIMG0208.JPG

    You will need to disassembly and clean them carefully.
     

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  5. Sansuiman

    Sansuiman Active Member

    Messages:
    387
    Location:
    St. Louis, Missouri
    ^ if I understand the OP correctly, it is the balance pot at issue. Assembly pictured above is a rotary switch typical of a source selector or Dolby mode selector as used in Dolby equipped models (e.g. 9090DB, G9000DB, QRX-9001 etc.).

    The pot will be a two gang semi-sealed unit if a typical Alps or Noble design, there is usually a small ball bearing or formed ridge of some type internally that rests in a "notch" at the detent point (center position) to provide the stop. Might get lucky and get it freed up with some deoxit and faderlube to follow up, but if something mechanical has broken or shifted internally, then disaasembly of the pot is probably the only option and then there is no guarantee it can be repaired, rather than replaced outright.

    I have repaired pots, as have others on here in threads I've read. It is very delicate work tearing down a multi-gang unit without damaging something and trashing the whole part. Reassembly can also be tricky due to the rearmost gang usually being held in place by the end of the aluminum shaft being mushroomed out as a retainer. Then a new method to hold the wafer and corresponding wiper mechanically in place is needed since the stamped end of the shaft had to be carefully removed to permit disassembly to begin with.

    Not knowing the skill and comfort level of the OP, this type of repair may not be practical as a DIY project.
     
  6. kevzep

    kevzep Its all about the Music Subscriber

    It is, but there is also an issue with the -20db Muting switch. Since the unit needs to be opened up, its a good time to do some much needed maintenance.

    I have been in side a G9000 very recently, and actually had to remove the balance pot to repair some broken traces on th circuit board, they are a cheap pot, nothing special at all.
    It might have an oxidised shaft which has bound up, or the ball bearing has caught up or whatever, but it needs to be removed to see what the issue is.

    I am sure the OP can assess if his/her skills are up to the task, its a free world and we are all here to help each other.
     

     

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  7. Hipocrates

    Hipocrates Anti-Muppet Subscriber

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    Oops my bad... I did not read well. Sorry
     
  8. Zeke

    Zeke Demi-God of Brilliant BS!

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    Sadly, while I know a bit about some things, electronic repair is not it.

    Living in Kansas City until three years ago, I'd always been fortunate to be near one of Audiokarma's most appreciated technical guru's who rebuilt this unit's power supply and went through all the switches 6-7 years back. Then, unfortunately, it sat in climate controlled storage for a few years as I rebooted my life. Daily use the past three years.

    Currently, the amp section is fabulous but the tuner receives intermittent stereo so I stream or use iTunes.

    I'm 5-6 hours from Seattle or Portland, you'd think we'd know someone from there on this site who could replace this pot and align a tuner? :)
     
  9. Hipocrates

    Hipocrates Anti-Muppet Subscriber

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    I don't know if is too far away, but QRXrestore is en eugene oregon and blhagstrom is in Duvall.
     
  10. Zeke

    Zeke Demi-God of Brilliant BS!

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    Seven hours and five hours, both near great breweries.

    NOT "too far away." :)
     
  11. Hipocrates

    Hipocrates Anti-Muppet Subscriber

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    Holly molly!!
     

     

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