Mixer main and monitor out staticy and drops out

Discussion in 'Amp Tech Center' started by KCKC, Mar 30, 2020.

  1. KCKC

    KCKC Tele-Afflicted

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    Hey guys,

    Wasn't sure where to post this. Hope I'm in the right place...

    I've had my Alesis multimix 8 usb 2.0 FX (discontinued) for approx 7 years. It's been great until recently. Over the past few months mic channels 1 & 2 have become staticy and intermittent, 2 days ago the main and monitor outs and headphones have gone the same way.

    It can be staticy in a way that follows the beat of the music or pulse of the voice of an online guitar lesson.

    Sometimes if I turn it off, wait a bit and turn it back on it's fine for a while. Other times there's the static and other times it just drops out - no sound. But, during no sound if I crank the vol. it sounds super faint and far away.

    There have been occasions where it has been left on for extended periods of time (days :() and there are a number of mentions online about how hot the unit can get. I would imagine this is not good for it.

    Could my solution be as simple as canned air or contact cleaner? I went through the manual trouble shooting section to no avail. I checked cables, headphones and they are working properly. I still have to check my monitors (Yamaha powered 5"). I am pretty handy, have done some soldering work, but never on circuit boards.

    I can't imagine a firmware or driver update or delete/reinstall would solve this.

    I am a stingy swamp yankee, who hates to toss stuff that can be fixed. Any thoughts or suggestions would be great.

    Thanks,

    KC

    Clarification: I have the multimix 8 USB 2.0 FX - This allows for recording to 8 separate tracks at once and is discontinued. This is different from the currently available multimix 8 USB FX which only has output to a single stereo track not sure if this makes a difference in diagnostics.

    Manual:

    https://www.alesis.com/products/view/multimix-8-usb-2.0-fx

    REQUIREMENTS
    • MAC: OS X 10.4.1 to 10.11
    • PC: Windows 10 (32 or 64 bit), Windows 8 (32 or 64 bit), Windows 7 (32 or 64 bit), Vista (SP1; 32 or 64 bit), or XP (SP2)
    • Available USB 2.0 Port
    Schematic:

    https://www.manualslib.com/manual/3994/Alesis-Imultimix-8-Usb.html?page=31#manual
     
  2. wabashslim

    wabashslim Tele-Afflicted

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    Contact cleaner first but it sound like maybe you've got dying parts. Look over the solder, touch up anything spotty. If it's still acting up while you've got it open start tapping on parts with a wooden/plastic stick to see if something's touchy.

    Nothing lasts forever and it is an Alesis after all...
     
  3. Lowerleftcoast

    Lowerleftcoast Tele-Holic

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    Try the contact cleaner as mentioned above along with wabashslim's other advice. The mixer may have jacks that have switches on them. Those contacts need to be cleaned as well. Run paper or very fine sand paper (1000 grit or finer) thru the contacts to get the oxidation off. You do not want to sand thru the contact surface.

    It is old enough that the electrolytic capacitors can start failing. If the above does not cure the problem you could try changing the electrolytic capacitors.

    If it has smd topology it will be very difficult to fix due to the tiny parts.

    Good luck.
     
  4. KCKC

    KCKC Tele-Afflicted

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    Thanks Lower,

    Yeah, I have pretty chubby, sausagey fingers. Small parts would be a challenge. I'll try the contact cleaner and light abrasion!

    If it doesn't work... I'll take it from there!

    tx again guys!

    KC
     
  5. Lowerleftcoast

    Lowerleftcoast Tele-Holic

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    Chubby, sausagey fingers? You must play slide guit.:D
     
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  6. KCKC

    KCKC Tele-Afflicted

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    The four fat strings in the bottom end! :lol:
     
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  7. sjoko

    sjoko TDPRI Member

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    it's fixable ! ,...I use a tiny baby solder-iron and a magnifying glass with lighting to fix such equipment ,
    but .....here's an example for what it cost new at the moment :

    https://www.thomann.de/nl/alesis_multimix_8_usb_fx.htm?sid=5aec0f7622a127fd99b706d60947f1fe

    I can tell you , ( and I'm pretty sure ) that it's not a matter of defective components in that mixer.
    Nowadays the parts in such equipment will not be soldered in a solder bath during production , but in a special dedicated oven , due to the SMD components on the pcb's , which will generate unsufficiant heat to make decent solder joints for the bigger parts on that pcb.
    What will occure after several years , is that the bigger parts ( not active components ) , such as XLR and Jack inputs will come loose due to bad solder joints on account of a phenomenon , called "galvanic corrosion".
    It's possible to resolder these bad solder joints , but it's a little tricky to get that job well done , because the special SMD solder will not mix with conventional solder that easy.
     
    Last edited: Apr 1, 2020
  8. KCKC

    KCKC Tele-Afflicted

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    Sjoko, thanks for the reply! That's the link to the multimix 8. It's my understanding that you can have inputs on all 8 channels the the output is only one stereo/mono track. The multimix 8 usb 2.0 would allow for the assignment of output to 8 separate tracks. This was a great little unit for the price - around $250 if I recall.

    Either way I don't think that that would affect my issues.

    First I will try the contact cleaner and if that doesn't work I may remove the housing and see if I can locate any cold solder joints.

    I'm flying blind here!!

    KC
     
  9. The Ballzz

    The Ballzz Tele-Afflicted

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    @KCKC
    I'm betting the switches are dirty and/or oxidized. Befor contact cleaner, the next time a channel cuts out, try cycling each switch several times. Also understand that any contact cleaner should have lube in it.
    Just Sayin'
    Gene
     
    Last edited: Apr 1, 2020
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  10. sjoko

    sjoko TDPRI Member

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    Be careful with contact cleaner ,....and do NOT spray on the plastic axles of these potmeters . These type of potmeters can't be fixed with contact cleaner at all , because the housing is totally closed. If you should think ,..what the hell , ..I'll give it a try , then you will discover about a few days that the axles are stuck . ( no way you can turn them anymore :D )
     
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