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Zoom 9030 zero output fault

Discussion in 'Troubleshooting and Repair' started by coolin, Nov 4, 2016.

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  1. coolin


    Nov 2, 2013
    Hello all,

    I recently acquired a Zoom 9030 early-90s FX rack. The seller was offering it as "lights up, unable to test".
    When it arrived in the post, it came with a Creative Labs PSU - connecting it with this for a moment powered the unit up but with blocks across the LED display.
    Attaching an appropriate PSU, it does now come on properly and patches can be changed on the front panel; however, there is no instrument signal in the output. All I can hear is the whooshing of the phaser, or the fizzing hi-gain of the overdrive for example.

    Before I open this up - what should I be looking for? I can recognise and replace a bad capacitor, but I get the feeling the A/D converter might be fried. Should I be looking for an IC to replace?

    I've been after one of these for some years and they rarely come along, so happy to spend some money on parts & labour.

  2. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
    All kinds of defects can lead to this behaviour. You'll have to open the unit and follow the signal from the input all along it's way to the output. Once the signal vanishes between two points, the defect is in the circuit in between these point.
    It surely helps to have a schematic diagram of the unit's circuit and a signal tarcer like e.g. this one.

    First thing to do is an optical inspection. Sometimes the defect is as simple as a loose connector or a broken wire/trace on a PCB. You may also find components that look damaged, but not every component that doesn't look brand new (unlikely given the age of the rack) is defect. This has to be decided ona case to case basis. Show us good photos of the suspect parts (PCB, components) to help us identify possible issues.

    Good luck for restoring the rack!
  3. coolin


    Nov 2, 2013
    Thank you Harald - that's a most heartening start, I shall have a look over this weekend.

    Johnny Coolin
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