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Dynacord VRS 23 BBD delay repair - no effect on one delay setting

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  • Dynacord VRS 23 BBD delay repair - no effect on one delay setting

    Hi everybody

    unfortunately my Dynacord VRS 23 delay has developed a problem

    The longest one of the four delay time settings doesn't produce effect sound anymore

    Other three shorter delay settings operate normally

    The reverb setting doesn't make any change so there's a problem with that too

    I have been trying to follow the signal path with a signal generator and oscilloscope in order to find where the signal gets interrupted, but the circuit is very complex for my abilities and i got completely lost

    The circuit design has some kind of symmetry. Two NE570 companders and 5x BBDs per side. I can see there is some difference in signals going through these two "channels" but i don't know how to interpret these. I also been trying to swap the ICs between the two sides but that didn't really make a difference

    I would really appreciate if a more expert eye could give a quick look at the schematic and make some suggestions on which points in the circuit need to be checked

    Here you can download the original service manual with schematics

    http://fa.utfs.org/diy/dynacord_vrs2...viceManual.pdf

    Thanks in advance

  • #2
    Originally posted by beatnik View Post
    Hi everybody

    unfortunately my Dynacord VRS 23 delay has developed a problem

    The longest one of the four delay time settings doesn't produce effect sound anymore

    Other three shorter delay settings operate normally

    The reverb setting doesn't make any change so there's a problem with that too

    I have been trying to follow the signal path with a signal generator and oscilloscope in order to find where the signal gets interrupted, but the circuit is very complex for my abilities and i got completely lost

    The circuit design has some kind of symmetry. Two NE570 companders and 5x BBDs per side. I can see there is some difference in signals going through these two "channels" but i don't know how to interpret these. I also been trying to swap the ICs between the two sides but that didn't really make a difference

    I would really appreciate if a more expert eye could give a quick look at the schematic and make some suggestions on which points in the circuit need to be checked

    Here you can download the original service manual with schematics

    http://fa.utfs.org/diy/dynacord_vrs2...viceManual.pdf

    Thanks in advance
    Hi, did you manage to find the problem? I have the same issue, and am completely stumped.

    Cheers,
    j,

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