Help...MA5100 not playing left channel?

Discussion in 'McIntosh Audio' started by joekapahulu, Jan 18, 2019.

  1. joekapahulu

    joekapahulu Active Member

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    Location:
    Honolulu, HI
    Ok, put my MA5100 I in queue for 1st in 3 years and the left channel is not playing in stereo. Works in mono, and when I use reverse stereo on switc as well as when I send right channel signal to both sides. Does not work when I send left channel to both sides. So, I am thinking this is a preamp issue not something in the power amp section? Unit was fine 3+ years ago after Terry DeWick upgraded it.At that point I had noise coming out of that channel. Any things to try before I have to decide on how/If to get fixed?
     

     

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  2. nj pheonix

    nj pheonix AK Subscriber Subscriber

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    My first thought is a dirty control or switch.
    Then a loose connection .
    Does that have separate connected switch, pre out, line in jacks with jumpers?
    Tape mon switch, mute switch.
    I'd check, clean those first.

    Often times it's something silly (obvious)
    We've all done it one time or another
     
  3. nj pheonix

    nj pheonix AK Subscriber Subscriber

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  4. joekapahulu

    joekapahulu Active Member

    Messages:
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    Location:
    Honolulu, HI
    I have done the deoxit thing on this amp before. The volume and speaker switches can get noisy. Can't hurt to try it although it seems odd that the stereo channel is the only one affected, ie both sides play on mono. That would seem to suggest the problem is electrical vs mechanical. But crazier things have happened. Will have to give it a shot this week.
     
  5. nj pheonix

    nj pheonix AK Subscriber Subscriber

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    The signals are very low voltage .
    Any point of non contact will stop signal in its tracks.
    I sounds like issue is in preamp section, which narrows it a bit.
    If you can't solve by contact cleaning you likely need a tech.
    A can of contact cleaner and a few minutes (An hour?) Of your time is cheap and easy.
    Also you said Terry D had it and he does excellent work so I'm thinking it's nothing serious .
    No guarantees mind you but I'm betting you fix it.
     
  6. JayPare

    JayPare AK Subscriber Subscriber

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    Montreal, Qc, Canada

     

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  7. joekapahulu

    joekapahulu Active Member

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    267
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    OK, looking to do this so thanks for the reminder on how. However, one minor issue. I have 2 cans of Radio Shack Deoxit knockoffs because thats all I could find out here in HI when I was looking 4 years ago...and I couldnt get it shipped to me from an online source due to the "threat of explosion"...same issue has hit me for a number of other things like Wood Cleaner, ECCO shoe cleaner...but I digress. Anyway, the RS Products I have are labelled as Electronics Cleaner and Electronics Cleaner and Lubricant....does anyone know which might be which as clones of the DeOxit items? the last time I used them I simply sprayed the parts then left the gear open to the summer air for about 2 weeks on the dining room table figuring that would dry them out. That nearly caused a divorce so its not likely I can do it the same way this time...plus since its not summer and has been raining cats and dogs, eating outside on the lanai is not in the cards.
     
  8. IvoCRO

    IvoCRO Active Member

    Messages:
    105
    Location:
    Zagreb, Croatia
    If this is the one you are talking about, then I would first use cleaner. Spray it on switch or potentiometer, work few times, like push switch several times or rotate pot back and forth and after that spray just a bit of cleaner and lubricant, and work few times again. After that you don't have to leave it dry on air for weeks or days at all, unless instructions on spray says different, but I doubt that drying time should be more than few minutes.
     
    Last edited: Feb 14, 2019 at 5:52 AM
  9. joekapahulu

    joekapahulu Active Member

    Messages:
    267
    Location:
    Honolulu, HI

    Thanks for the response. Looks like it might be the same thing....similarly named, though looks different packaging. In any case, I am going to try the approach you recommend. In thinking about it,it sounds logical based on the quoted capabilities on the side of the can. I will probably let it dry a couple of days...no rush and I do have a phobia of fire/reaction to electricity. Probably due to lack of ANY training on this stuff. Kind of like my interest in tube amps....love the sound but a little phobic over what it takes to maintain them.....thanks again. Aloha.
     

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