Tascam porta 07 hum /static noise issue

Discussion in 'TASCAM DIY Repairs and Mods' started by johan englund, Feb 4, 2018.

  1. johan englund

    johan englund New Member

    Joined:
    Feb 2018
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    Gear:
    porta, mixer
    Hi

    I did a search in the forum but I didn't find anything that matches this problem. I've got the original PS-02 psu and the machine powers on normally, there's also no issue with the tape transport. I've not been able to test the capacitors but overall the insides look clean and there's no sign of leakage anywhere.

    Here's a video of the issue:

    Any advise is much appreciated! Many Thanks

    Johan
  2. SkywaveTDR

    SkywaveTDR Well-Known Member

    Joined:
    Feb 2014
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    From:
    Chicago area
    Gear:
    Teac, Tascam, Sony
    If it is on all tracks I would suspect that the internal regulators are oscillating. I would put a scope on the output of the regulator to see what is coming out. There should be clean DC but there are those that fail in ways that they add noise to the DC going out due to current overload or that they are just defective. We at Teac normally replaced LM78M12 with the full power LM7812 so that the current demand did not cause further problems.
    The power supply may deliver a DC voltage to the unit but then there are regulators inside to get that stable such as plus and minus 12Vdc. Each unit is different.