Tubeworks Real Tube 12ax7a design analysis

Here is a design analysis I did for a client. It is a guitar effects unit, a so-called "stomp box".
        QUALITY- FAIR
                   -Flux left on circuit card.
                   -Unsoldered pads on circuit board.
                   -Transformer retained by pop rivets.
                   -Solder wicked into multi-strand wires.
                   -LEDs unsupported.
                   -"Fixes" soldered to back of board.

        REPAIRABILITY/MANUFACTURABILITY- POOR
                   -No silkscreen or component designators.
                   -Hardwired components captivate board to
                    enclosure.
                   -Components underneath tube socket.
                   -Close tolerances to enclosure may cause
                    shorts.

         DESIGN- FUNCTIONAL BUT EXPENSIVE
                   -Two op amps used as flip-flop to toggle
                    effects.
                   -Eight large electrolytic capacitors.
                   -Metal shaft potentiometers.
                   -Three different potentiometer values used.
                   -No surface mounted components utilized.
                   -No high frequency rolloff -- will damage
                    tweeters.

         LEGAL- NON-COMPLIANT
                   -High voltage in unit without earth ground or
                    double insulation.
                   -No U.L. Listing.
                   -High and low voltages in close proximity.

         RECOMMENDATION:
                   -Report non-compliance to FTC and Underwriters
                    Laboratories so this product will be recalled
                    from the market.
                   -Design alternative product which eliminates
                    ground loops in a safe manner and achieves
                    cost reductions by good design and
                    manufacturing practices.

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This page contains a single entry by Paul Rako published on July 2, 2011 9:52 AM.

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