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ALL PAN POTS STOPPED WORKING!!! WTF!!!

Discussion in 'Recording' started by lightandmind, Apr 8, 2007.

  1. lightandmind

    lightandmind Guest

    :eek: Every channel on my Tascam 388 is now like it's stuck in Mono. The ability to pan went out while powering up, (Mono button is rarely used and not stuck- not the problem). All pots refuse to pan anything. Only the overall volume is slightly decreased when L/R, (strongest in the middle). I know this is an easy fix, just need to know what/where. Can't even remember the last time I used touched the Mono button, plus- when I now press-it, it still makes that small click and seems to activate, (even though it sounds pretty much the same), so I know thats no the prob. I know the problem is internal because the meter is only registering in mono as well. I've been doing a lot of work on it lately, even had a bulb in the meter go out on me in the same week!, (funny how they look like a missing tooth). Nothing out of the ordinary. Shortly before that, I powered up my power-conditioner, not realizing the mixer power-switch was already turned on (so it immediately lit up, not THAT big of a deal I would think,,,). And that's all I can think of. Never any problems ever and I just flipped her upside-down and cracked her open (she likes it rough sometimes), and cannot see anything out of the ordinary. I'm stumpted. If anyone know what to check and where, PLEASE leave some info, I'm begging you. I can replace caps, resistors, PCB boards etc, just need to know where to start looking. Thanks a bunch guys!

    P.S. JUST finished Tracking a clients project that still needs mixing!!! Pleeeeease help!
     
  2. RemyRAD

    RemyRAD Well-Known Member

    Your descriptions really doesn't make any sense. If you start with a single input module and assign that to the left/right mixing bus, if you're left/right output meters do not reflect any change from the pan pot, it might be some kind of left/right insert problem? If you have inserted a device on the left/right mixing bus insert, you might be losing your stereo there? It sounds as though you have mono summed the left/right mixing bus somewhere,with some kind of wiring error? It's not a digital console and so there is no software to glitch. Its operator error.

    Abracadabra!
    Ms. Remy Ann David
     
  3. guitarbill

    guitarbill Guest

    Yo, Remy's right about checking your inserts ect. You need to rule out op error. Does every channel have the same symptom?
    Since you say you've been working on your 388, I'm going out on a limb here thinking that something degraded upon disassembly and suggest you look for a connector missing a crucial ground (on your mix bus perhaps) or perhaps something shorted where no short should be. Let your meter and schematic be your friend here and you will find it sooner or later.

    good luck
    gb
     
  4. lightandmind

    lightandmind Guest

    every channel is the same thing. I have NO inserts or sends hooked up, only monitors, but like I said, the problem is internal because even the main VU reads constant mono. Thanks for your help!
     
  5. RemyRAD

    RemyRAD Well-Known Member

    You have lost ground reference on the pan pots, in the mixer section. Somehow, a ground wire that may actually be extended from the circuit board to be screwed somewhere on to the enclosure may be providing a ground reference. Pan pots can typically be made in 1 of 2 different ways. They can be something as simple as a single 10,000 ohm potentiometer where signal is injected into the wiper and is fed out of either end, to the numeral to track mixing bus.

    Whereas it can also be a dual ganged potentiometer where depending upon its positional rotation is turning up one of the potentiometers while turning down the other potentiometers and if the ground reference should be interrupted or less than ground potential, you would have this problem. The question now is, what has happened internally to the mixer? Hasn't recently been opened for service or inspection?

    I think we're getting closer?
    Ms. Remy Ann David
     
  6. lightandmind

    lightandmind Guest

    Nothing out of the ordinary. A bad ground is the best suggestion I've heard yet- thanks. Moving the pot back & forth does not interfere w/the other channels, if that helps. I've just been doing a bit more work on it lately. She's been great up until this point. Whatever it is, it's affecting the pan-output on each individual channel, individually. There's nothing I can do to make the Main L/R VU meter to read anything but Mono. Thanks again for your help!
     
  7. lightandmind

    lightandmind Guest

    Anyone? I guess it's off to the repair man! : )
     

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