Akai x-165d need sub for 2SC971

Discussion in 'Tape' started by eizner23, Oct 11, 2018.

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  1. eizner23

    eizner23 Well-Known Member

    Messages:
    551
    Location:
    Madison, WI
    Looking to sub 2SC971 in a Akai x-165d oscillator board. 2SC971 is a TO-5 device with a heatsink.
    Service manual
    I found two possible modern subs: ksc2690 (to-126) and ksc2073 (to-220)

    2sc971
    Pc = 1W
    cbv = 50v
    ebv = 7v
    Ic max = .5A
    ft = 30mhz
    hFE = 80 min

    ksc2073
    Pc = 25W
    cbv = 150v
    ebv = 5v
    Ic max = 1.5A.
    ft = 4mhz
    hFE = 40 min

    ksc2690AYS
    Pc = 1.2w
    cbv = 120v
    ebv = 5v
    Ic max = .1.2A
    ft = 155mHz
    hFE = 160 min

    ksc2690AYS seems like a closer match, ebv is a little low, pins should fit existing holes but its much faster @155mhz. How would this affect oscillator? Would a heatsink be required for new device since heat dissipation is much better?

    osc.jpg
     

     

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  2. dhnash

    dhnash Well-Known Member

    Messages:
    579
    Location:
    Wildwood, MO
    Exact replacements are apparently still available.
    https://www.ebay.com/itm/NTE-2SC971...g:q74AAOSwslda0Nkk:rk:1:pf:0&shqty=1#shpCntId

    The transistion frequency of the KSC2690AYS shouldn't be an issue since it is higher than the original part. Use of an appropriate heatsink is required to allow the transistor to operate at its rated power dissipation.
     
    Last edited: Oct 12, 2018
  3. eizner23

    eizner23 Well-Known Member

    Messages:
    551
    Location:
    Madison, WI
    thank you for confirmation and info :)
     

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