Sudden phantom voltage swings

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  • #49337
    Profile photo of ddff_lvddff_lv
    Participant

    Hi,

    I’ve been reported about really strange glitch with my iDR32. It was working outdoors event and one of multicores in which some channels had phantom power enabled got rain. After this some of channels with condenser mics connected started to change gain from no signal to full blast. Engineer also noticed that the LED on the BSS AR-133 DI-box is off and turns on along with this gain swing. So he assumed and I tend to agree the gain change might come along to voltage change of phantom power. Tricky part is – the behaviour was not happening only on the inputs that had the water filled multicore connected before, but also on the different channels, even in different inputs rows. So here’s some questions – does the iDR have one central phantom supply or there are step-up converters on each I/O PCB or even for each input socket?
    How some shorted (if they were shorted after all) inputs would affect whole supply if there are current limiting resistors for each input?

    I will try to recreate this situation in shop by setting a long recording of signal generator through active DI and analysing the waveform after.

    ddff

    #49643
    Profile photo of ddff_lvddff_lv
    Participant

    OK, now the phantom is gone. Had a quick look at the PSU and got a question- what is the advantage using DC/DC convertor from 24V instead of having one secondary winding, a diode and capacitor?

    I guess, I’ll order new PSU board and try to fix the old one for backup.

    ddff

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