Corrosive glue in 80's gear?

Discussion in 'Exclusively Sansui' started by Robisme, Nov 10, 2017.

  1. Robisme

    Robisme Sansui Enthusiast Subscriber

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    Yup.

    I have this Z-5000X here that had developed a low hum. A while back I ordered some caps, diodes and resistors to try and repair this thing. There is a lot of corrosion due to glue. As I was replacing the parts affected by the glue, I found this. The glue ate right through the lead.

    upload_2017-11-10_15-39-13.png

    Any way, after replacing the parts and cleaning the glue, the hum is gone.

    Rob
     
  2. KingBubba

    KingBubba "Too Much Stuff" Subscriber

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    My Sansui 9900zdb has the glue for sure. It may be the non corrosive version because the receiver is still in action and I do not see any local damage around the caps.
     
  3. pete_mac

    pete_mac Super Member

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    My AU-X701 had the dreaded glue corrosion.
     
  4. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    And also my AU-X701, and AU-D11 II, B-2102 and C-2102.
     
  5. LBPete

    LBPete Rolling Along Subscriber

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    Sansui seems to have used different glue formulas at different times during production. The glue used later in the 1970s seems to be more prone to corrosion than the glue used in the early 1970s. My only encounter with true glue corrosion was in a G-22000. All of the models mention above were built after the G22. I've seen many, many board from models built in the early - mid 1970s slathered with glue but no actual corrosion. There must be an environmental element too or the lead corrosion issue would be more wide spread.

    I also think there were variations to batches of glue used. I've seen big G receivers with two driver boards, the glue turned black on one board and didn't on the other. That kind of rules out an environmental cause to the discoloration.

    - Pete
     
    bolero likes this.
  6. JOMARK911

    JOMARK911 Super Member

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    2,504
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    Athens Greece
    I have some units my self. Never faced the problem of glue, from the eight to G22000 G33000 BA5K BA3K BA2K CA3K ,to the latest B2301 C2301 AU-X 911DG, B2302 and some others .
    Not even once and i think i should have faced the problem at least with 2301's . There must be an explanation why some units are afected and others are not.
    Have recaped almost all of em except the eight , and 2301's partially , never ever saw any coroded leg of a electrolytic or a diode or whatever. Except if i'm very lucky.
     
  7. Robisme

    Robisme Sansui Enthusiast Subscriber

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    That's interesting. I find the glue has gone corrosive is most units I work on. I have an AU-717 that is about the worst I have seen. From the driver boards to the power supply.

    Rob
     
  8. tom3

    tom3 Super Member

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    I would maybe suspect moisture with cigarette smoke might cause a reaction with the glue? Sure seems to mess up electronic equipment after many years of exposure. And a lot of the older gear was in homes without AC, as was my original setup, and I smoked back then too.
     
  9. Robisme

    Robisme Sansui Enthusiast Subscriber

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    I thought maybe heat. In some of the gear I have worked on, I noticed that the glue was darker near hot points in the unit.

    Rob
     
  10. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    I always thought it was humidity, requiring the gear to be 'off' for long enough between periods of use for the glue to suck up the moisture. But maybe it's just a combination of all the things suggested. :idea:
     
  11. kevzep

    kevzep Its all about the Music Subscriber

    That's what I have noticed too, seems to be almost always around regulated supplies...
     
  12. ConradH

    ConradH AK Subscriber Subscriber

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    Roughly, very roughly, most chemical reactions speed up by about double for every 10 degrees temperature rise. If things are perfectly dry, not much is going to happen at all. So, some combination of humidity and temperature is probably at play. I've seen glue have no effect at all, and I've seen it eat the legs right off components. Since the equipment in question is usually Japanese, I've always wondered if the stuff is some variation on fish glue that's more flexible than what's used for woodworking and for various arts.
     
  13. pustelniakr

    pustelniakr Silver Miner at Large Super Mod Subscriber

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    Appears to be as formulation related to contact cement, likely because it was fast. We used a special hot glue for out production. Worked better, and was safer.

    Enjoy,
    Rich P
     

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