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Dunlop rotovibe stops working suddenly

Discussion in 'The Effect effect' started by fenderjack, Aug 15, 2019.

  1. fenderjack

    fenderjack Strat-Talk Member

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    any idea what could happen? I jsut saw it minutes ago, the leds are not working anymore and so the effect is dead.....i did nothing to it, no physical damage....juse suddenly it dropped dead.....i have several effects on at home and this never happened before to any effect I have.....what to do
     
  2. Stratoskater

    Stratoskater Most Honored Senior Member

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    Change the battery or check the power supply?
     
  3. fenderjack

    fenderjack Strat-Talk Member

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    i tried battery and i use power charger for all my effects so nothing changed...something else is wrong.....i hear the click in speaker when i switch on the pedal...so it must get signal throgh....also if I do not power it up, the signal does nto go through
     
  4. JB74

    JB74 Senior Stratmaster

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    if you use a wallwart, is it the correct voltage and polarity?

    Take the bottom cover off and look at the transistor and electrolytic cap right beside the power input jack.
    dsc00015.jpg

    likely fried.

    dsc00010.jpg

    replace.

    dsc00014.jpg


    good to go.
     
    Last edited: Aug 15, 2019
  5. fenderjack

    fenderjack Strat-Talk Member

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    it worked fine for like 2 month since I got it...
    can you be more specific what to check? And how to see if it is fried? I have multimeter though
     
  6. JB74

    JB74 Senior Stratmaster

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    @fenderjack see pics above and 2 schematic below (one is pdf)
    Q7 is an MPSA18 BJT (NPN)
    Rotovibe-Dunlop-Rotovibe.gif
    change out the electrolytic as well if it's nasty.
     

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    Last edited: Aug 15, 2019
  7. fenderjack

    fenderjack Strat-Talk Member

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    thank you so much for being so kind......i tried to mess with my multimeter to see if something is broken....even the input power jack did not give any voltage reading....maybe i id not do it right....how much would this cost? You think it fried cause of power surge? I have many effects and all are ok, only this one is broken.....
     
  8. JB74

    JB74 Senior Stratmaster

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    Surge most likely, and not all circuits are created equal. it will help if you take some sharp close-up pics of your board, start looking for scorch marks or solder joints that are a crystalline-silver as opposed to shiny. It could be at the point where simply bad solder joint has prevented it from operating, but this is also usually a precursor to a component failing. Thermal cycling or overvoltage is the most common issue on these. That BJT is a common component that fails due to overvoltage in these units. the caps could be leaking- although not really likely unless it's an old pedal. It is always better to replace on proximity if there is obvious component damage such as the magic smoke released from an mpsa18...
    It's not possible to make a definitive diagnosis on ze intervebz. However you can help us to help you find the issue.

    check the obvious things... is there signal in, is there power in, where does it stop, go back one component test etc etc. obviously easier with a scope, but a DMM will get you there on a voltage measurement.
     
    Electgumbo likes this.
  9. fenderjack

    fenderjack Strat-Talk Member

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    I wonder how bad is this effect made together....I used 1spot pro power charger...the best there is....and also belkin surge protector.....
    is it possible it is the switch button fault....that when you press pedal down it does not engage 100 %...I hear the click but maybe that is the fault...i checked for any burn marks near power plug on effect, nothing visible......i will do some shots today with macro lense....
     
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