Home › Forums › Help/Technical Questions › Small Clone passing signal but not ‘chorusing’!

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  • September 11, 2010 at 8:21 am #80719
    wsal
    Member

    Hi all,
    I have a Small Clone pedal – not sure how old, it was bought second hand, and all of a sudden it’s not working properly. It still allows sound through both switched on and bypassed, but it’s not providing the proer chorus sound anymore. It does however, sound different when switched on – I think it sounds like the basis of the chorus effect is there but not modulating at all – just ‘stationary’. Also, when flicking the Depth switch and holding a note, there’s a definite change of sound. If anyone can advise how to attach an mp3, or is willing to provide their email address, I can send a short clip demonstrating the above.
    Can anyone help out?
    Thanks in advance
    Will

    September 11, 2010 at 12:10 pm #111344
    The EH Man
    Moderator

    You might try adjusting the trimpot. There’s only one but be sure to mark it’s original position with a marker before turning it.

    September 11, 2010 at 12:28 pm #111343
    empty
    Member

    i have a similar issue with my small stone – passing signal, but not phasing.
    would the same advice apply to my problem, the eh man?
    thanks.

    September 11, 2010 at 12:52 pm #111342
    The EH Man
    Moderator
    Quote:
    i have a similar issue with my small stone – passing signal, but not phasing.
    would the same advice apply to my problem, the eh man?
    thanks.

    No. There are no trimpots in the Small Stone. Yours likely has a dead op-amp in the LFO circuit.

    September 11, 2010 at 1:02 pm #111349
    wsal
    Member

    Hey EH Man, thanks for the reply
    I adjusted the trim pot in both directions and while it certain points at both extremes, the effect seemed to cut out entirely, nothing got the modulation going again…
    Cheers
    Will

    September 11, 2010 at 1:12 pm #111350
    The EH Man
    Moderator
    Quote:
    Hey EH Man, thanks for the reply
    I adjusted the trim pot in both directions and while it certain points at both extremes, the effect seemed to cut out entirely, nothing got the modulation going again…
    Cheers
    Will

    Sounds like the delay IC is working OK. Could be the 4047, which produces the clock signals for the MN3007 or the 4558 that drives the 4047.

    September 11, 2010 at 1:19 pm #111351
    wsal
    Member

    Ah okay. So how would I go about testing if that is the case, and if one of those components is to blame, are they easily replaced?
    Thanks again!
    Will

    September 11, 2010 at 1:26 pm #111352
    The EH Man
    Moderator
    Quote:
    Ah okay. So how would I go about testing if that is the case, and if one of those components is to blame, are they easily replaced?
    Thanks again!
    Will

    You need to check the LM358 (not 4558, sorry) for pulse on the output (pin 7). If it’s there, I’d replace the 4047. If it’s not, replace the LM358. You’ll probably need to rebias afterward.

    September 11, 2010 at 2:53 pm #111353
    wsal
    Member

    Hmmm, I’m starting to feel a little like this is outta my league, but I’m keen to give it a shot. In more basic terms, how do I check the pulse? It it just a matter of putting a multimeter across 2 terminals?
    Thanks for all the help so far!

    September 11, 2010 at 2:58 pm #111355
    wsal
    Member

    Additionally, I just checked the above IC number/codes on ebay, and they’re both very cheap. Is this a component that you can get away with buying cheap, or are there better “music grade” specialty ones available?

    September 11, 2010 at 6:47 pm #111356
    The EH Man
    Moderator
    Quote:
    Additionally, I just checked the above IC number/codes on ebay, and they’re both very cheap. Is this a component that you can get away with buying cheap, or are there better “music grade” specialty ones available?

    It’s not going to make a difference since no audio passes through them.

    Ground your multimeter black lead and put the red one on pin 7of the LM358. See if there’s a changing voltage level there w/ the Rate set about 1/2 way.

    September 14, 2010 at 7:52 am #111393
    wsal
    Member

    Alright, I checked the above, and there’s no moving voltage on the LM358, so it looks like that needs replacing?
    So, there’s a heap of them on ebay, yet some of them have extra letters added onto the name: LM358N, LM358DT, LM358DR – is there a particular type that I should look for/avoid?
    Cheers
    Will

    September 14, 2010 at 9:55 am #111395
    The EH Man
    Moderator
    Quote:
    Alright, I checked the above, and there’s no moving voltage on the LM358, so it looks like that needs replacing?
    So, there’s a heap of them on ebay, yet some of them have extra letters added onto the name: LM358N, LM358DT, LM358DR – is there a particular type that I should look for/avoid?
    Cheers
    Will

    LM358N is the one to get.

    September 20, 2010 at 6:12 am #111529
    wsal
    Member

    I replaced the LM358, and nothing has changed. I’m not sure I was checking correctly with the multimeter though – I put the black lead on the pedal case, and the red on the output pin – is this correct? If so, I was getting a reading of around 1.36v and it moves back and forth from there to 1.37v, but I wasn’t convinced that this was the ‘pulse’ you were talking about because it wasn’t moving at a particularly steady speed, and changing the rate knob made no difference to the speed…
    Anyway, with that in mind, do you have any more suggestions on what to check next?
    Cheers
    Will

    September 20, 2010 at 9:44 am #111533
    The EH Man
    Moderator

    Replace the 4047

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