McIntosh MC-2300 / C32 question

Discussion in 'McIntosh Audio' started by Slewfoot, Feb 11, 2019.

  1. Slewfoot

    Slewfoot New Member

    Messages:
    49
    Hi Guys,

    Hope all is well. Looks like I'm having a bit of an issue with regards to my system. As of now the right channel is not really working. The volume is incredibly faint, probably 5% of what it should be. You can hear the slightest bit of music when you put the balance all the way to the right. When I put the gain up on the MC-2300 amp the volume does increase so things are connected.

    I guess my questions are the following:

    - any troubleshooting I can do? I did the usual of make sure things are properly connected and that no buttons were pressed accidentally.

    - based on all this, do we think the issue is with the C32 preamp or the MC-2300 power amp? I do have a C34v as a backup and I can connect that to see, but the way things are setup it's a big pain to do so.

    Any insights are appreciated. Thank you, all!
     

     

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  2. 62caddy

    62caddy Trust but verify Subscriber

    Messages:
    9,951
    Location:
    NEPA
    Start by setting the MODE control to REVERSE. If no change, then reverse the L & R connections between the preamplifier & amplifier.
     
    CruzBay and stereocuuple like this.
  3. Slewfoot

    Slewfoot New Member

    Messages:
    49
    Thanks and the Reverse mode did not do anything, but when I switched the L & R RCA connections the right speakers then worked while the left ones did not.
     
  4. c_dk

    c_dk Addicted Member

    Messages:
    6,508
    Location:
    West Michigan
    So it would seem both amp channels are working.

    Rapidly rotate the variable loudness and balance controls to see if the dead channel crackles and tries to come in. These controls have a history of getting oxidized and affecting the output.

    When a unit comes in for testing those two controls are the first priority for proper cleaning, then if still a issue is present deeper analysis can be done.
     
    CruzBay likes this.
  5. Slewfoot

    Slewfoot New Member

    Messages:
    49
    Thanks! Tried that and didn't really crackle or anything. It just stayed the same where it plays a tiny bit of music at incredibly low volume.

    So it sounds like the problem is the C32 pre-amp instead of the MC-2300? That's good news as better to be that!

    Any other suggestions or should I try and replace it with the C34v and get the C32 inspected?
     
  6. c_dk

    c_dk Addicted Member

    Messages:
    6,508
    Location:
    West Michigan
    Yes time to swap in a different preamp to confirm the C32 needs service. The next level of testing involved cracking the case and probing for the place the signal stops.

    The first C32s came out almost 40 years ago so even the newest ones are 20 years past the expected service life of some of it's parts.
     

     

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  7. Slewfoot

    Slewfoot New Member

    Messages:
    49
    Thanks and will do! Much appreciated.
     
  8. damacman

    damacman Blown and Injected Subscriber

    Messages:
    9,137
    Location:
    Gilbert, AZ
    Exercise (aggressively) all switches, pushbuttons, and knobs on the C32 - including those on the top panel. I typically do this with the system ON and the volume at a low setting so that I can hear if I’ve identified the culprit. Of course, you can always switch the amp OFF if that scares you and listen with a pair of headphones plugged into the C32.

    I’ve seen many cases with Mc preamps where the Tape Monitor switches were the culprit of such a symptom.
     
    cjmustang69 and Bill Ferris like this.
  9. Slewfoot

    Slewfoot New Member

    Messages:
    49
    Thanks and I tried messing with all of those things before and still niente.

    I put in the C34v and all seems to be working well at the moment. The sound is a bit harsher than the C32, but it also hasn't been used in 3 years. Breaking it in now so imagine it will improve over the next day or two. Thanks to all for the input!!!
     
  10. c_dk

    c_dk Addicted Member

    Messages:
    6,508
    Location:
    West Michigan
    C32 uses relays to switch so the exercise is usually futile....

    Cold solder joints, especially certain Molex pin connectors in the audio path, failed ROE caps all can be suspect. Thorough pro switch cleaning always comes first, then the search begins.
     
    Bill Ferris likes this.
  11. Slewfoot

    Slewfoot New Member

    Messages:
    49
    Got it and thanks! I spoke to Mike at Hudson Valley Hi-Fi near me and he seemed to know his stuff about this unit. I'll probably drop it off to him in the upcoming weeks. Appreciate the insights!
     
    CohibaJoe likes this.

     

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