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Help with a Roland Jazz Chorus 77

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  • Help with a Roland Jazz Chorus 77

    I just picked up a Roland JC-77 that is not working.
    The person I got it off of dropped the reverb pan and in doing so took out the bolt holding a transistor mounted on the heat sink and it shorted on the chassis frying the tranny and the 330 ohm 5 watt power resistor.

    Now the transistor is only marked D716. Does anyone here know what the modern substitute would be for this?
    I actually registered on the Roland site and sent them an email but some big companies can be useless when it comes to servicing older products, hopefully it will not be the case here but that is why I am trying other avenues of info.

  • #2
    Welcome to the place.

    The number D716 is shorthand for 2SD716, an NPN 100v transistor in a TO-3P case. If you can't find them, perhaps something like the TIP35C will work as a substitute.

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    • #3
      Little Diode (UK) has them.
      I have bought relic parts from them before.
      1 week delivery from the UK.
      Link: 2SD716 Transistor x 1 pieces | eBay
      Watch out for the counterfeit stuff!!

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      • #4
        Thanks so much for the quick reply guys!!!

        Now this leads me to one more question. Do I need to change out all 4 of the transistors or just the blown one? If so do these need to be matched in any way?

        I am a bit of a newbie when it comes to troubleshooting amps so forgive me here.

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