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Help - LDR/ORP-60

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  • Help - LDR/ORP-60

    I recently discovered a new problem with a Gulbransen Rialto K I rebuilt. From what I can gather one of the light dependent resistors may be failing. These are referred to as "ORP-60" on the schematics. I cannot locate this part anywhere - probably long out of production. Does anyone here know if these are still being made, or if not what the equivalent LDR (they now seem to be called "photoresistors") would be? The ORP-60s look similar to modern-day phototransistors (a glass "bulb") but they are not prototransistors. I found an LDR called an ORP-12 but that looks very different than the ORP-60. I cannot locate a spec sheet for the ORP-60. Any information about replacing this part would be greatly appreciated. Thanks.</P>

    Jimmy Williams
    Hobbyist (organist/technician)
    Gulbransen Model D with Leslie 204

  • #2
    Re: Help - LDR/ORP-60

    Here is crude specs for the part:</P></P>

    And try to find at this link one that looks to be right shape/size:</P>;Ntx=</P>

    Resistance wise, look at VT23N1 which is HIGH PRICED...($5.73)</P>

    also VT93N2 which is low priced (40 cents).</P>

    Thses should offer useable resistance range so you need to look at specs for each and see what would fit.</P>
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