M320 Buss C Problem

Discussion in 'TASCAM Analog Forum' started by Sav2319, Apr 26, 2021.

  1. Sav2319

    Sav2319 New Member

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    Hi everyone, I'm new to the forum and Tascam equipment. Well, I guess I'm new to the world of electronics in general... but I'm having an issue with my M320 console where every track in buss C (tracks 1-8) does not get sent to the stereo buss. They can be sent to a subgroup and then I will get audio but sending those tracks directly to the L/R Buss will not work. Direct outs also work on every channel. Any ideas as to what the culprit may be?

    Thank you in advance,
    Vince
  2. SkywaveTDR

    SkywaveTDR Well-Known Member

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    Sounds like a buss bar PCB might have broken solder joints. This many failures from so many channels would be a part this is common with them off. a Scope and tracing a 1KHz signal would tell you more. With a mixer as complicated as this you can not guess you need to go in and probe around and find where a signal stops. Guessing will take you years.
  3. Sav2319

    Sav2319 New Member

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    Thank you for your response! I was thinking it had something to do with the buss bar but like you said I'm only guessing. My plan is to take out each strip for cleaning as well while I have it open and I can't figure out the best way to do so. Should I separate the buss bar PCB first or remove all 8 while still connected? I would then be looking to resolder the joints on the Buss Bar
  4. SkywaveTDR

    SkywaveTDR Well-Known Member

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    Not having a M320 manual in front of me the buss bars would come out as you see fit. If you recapped the whole mixer then all this should have been apart already. Resoldering the correct way with Kester 44 is the way I do these restorations. The M2524 I had here required some ground wires to be unsoldered to take the buss out as the mixer was worked on in the living room as it would not fit on my bench. I took them down to the bench and then resoldered them well. The power supply ground on this unit as I took that out and found out why problems were there. After resoldering there were no more problems. I have started to get rid of Marcon can when I see the larger ones as they are showing to be problems.
  5. Sav2319

    Sav2319 New Member

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    So I took a multimeter to the board and the circuit breaks on the last jump of the board on 11 and 12 which are stereo right and left. I'm going to attempt to resolder the joints and if that doesn't solve the issue could it be the PCB itself?
  6. SkywaveTDR

    SkywaveTDR Well-Known Member

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    To be honest. none of these wave soldering joints would pass aerospace soldering requirements which also means for use on commercial airlines- I used to work at Hughes. I resolder all joints on a part until they look shiny like they are suppose to and there is the right amount of lead on them not just a minimal amount. You will give the piece a much longer life if doing this. The most likely spot that failures happen is at connector headers or plugs as when they are plugged and unplugged this develops mechanical stress that the low grade soldering does not handle and the joints break. That is why when amateurs go into a X2000R and roughly handle all the cables like bulls in a china shop then they have many more problems when they get done putting a belt in. That is because they have broken a lot of joints and do not even know this. They really do not belong in such complicated machines anyway.