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NJD Spectre theatre stage light, 2003 date

Discussion in 'Electronic Repair' started by N Cook, Mar 28, 2007.

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  1. N Cook

    N Cook Guest

    Gives fully variable total spectrum floodlight output under remote control.
    Or it would but nothing now. Full of dust and fluff in the control area and
    a long term heat damaged , so presumably dramatically raised ohmage
    resistor.
    The bands are not discoloured , I think, reading 100 ohm , 5 percent and 1W
    size. Currently reading 47K, but scraping back the end thirds of the metal
    oxide spirals , the outer section thirds to each end are about 500 ohm each.

    This resistor connects mains live to in-series opto-coupler, then small 3W
    mains transformer primary (supplying just a 7805 for the microcontroller)
    then neutral.
    The opto is 4 pin P620 , presumably Toshiba TLP620 , current going through
    back to back LED of 50mA rating with transistor receiver.

    For the UK a 3W transformer would take about 12mA so 1.2V dropped across 100
    ohm, does that seem about right ? presumably uprating to 2Watt, 100R. The
    LED side of the opto seems ok at 1V diode drop either way.
     
  2. N Cook

    N Cook Guest

    According to www.njd.co.uk the schematic was available via email request.
    Nothing received so far though, so I will suck it and see.
     
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