Original Website © Amplabs 2009 This new site created April 2018

Quad 303 services (further details)


Before   fault   rectification   and   refurbishment:   right   channel defunct,   crackling   on   left   channel,   two   main   smoothing capacitors   leaking   and   there   are   numerous   faulty   &   out   of tolerance components. Rs, Cs, and semiconductors.
New    Nichicon    100V    105 oC smoothing    and    output capacitors   are   fitted   in   place   of   the   old   style   bracket mounting types.
On   older   303s   with   the   crude   diode   bias   arrangement we    can    fit    a    tiny    BIAS    modification    board.    This provides    a    more    precise    adjustment    of    the    output transistor   bias.      Incidentally   on   all   Quad   303   repairs we    carefully    set    the    bias    to    the    sweet    spot    for minimum    harmonic    distortion.    Too    much    and    THD      increases, to little, ditto.
We   mount   the   Nichicon   capacitors   using   our   specially designed    capacitor    PCB.    This    correctly    mounts    the modern   capacitors   in   place.   It   also   conveniently   allows the   inclusion   of   L   &   R   +rail   fuses.   In   the   event   of   a   blown output   device,   etc.,   a   fuse   blows   rather   than   a   vaporised PCB   track.   In   this   example   we   replaced   a   failing   bridge rectifier.  
Some   3O3s   we   receive   for   service   are   in   a   very   poor   state.   e.g.,   rusty   case,   bottom   plate   and   front   panel.   We   can   restore   the overall   look,   for   an   additional   cost,   by   stripping   and   re-spraying   these   parts   with   primer   and   top   coat.   The   re-sprayed   sections (cover and bottom panel) will be in two tone colours similar to the original but not perfectly colour matched.
For   ure listening pleasure