Pioneer m-25 power transistors info needed !!!!

Discussion in 'Pioneer Audio' started by McMarantz, Oct 16, 2011.

  1. McMarantz

    McMarantz Active Member

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    114
    Location:
    TURKEY
    HI ALL
    I NEEDED INFO ABOUT PIONEER M-25 POWER AMP POWER TRANSISTORS
    WHICH TRANSISTORS I CAN REPLACEMENTH TO MN25 AND MP25 POWER TRANSISTORS?:scratch2:
    Thanks
     
  2. ph2113

    ph2113 Member

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    78
    Location:
    Taiwan
  3. markthefixer

    markthefixer On Hiatus, dealing with Dad's estate full time Subscriber

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    Those are to-3 cased ring emitter transistors, with a very high MHZ specification - 45 to 60 mhz.

    these STMicroelectronics transistors are probably the closest available anywhere:

    2ST2121 PNP to-3 250V, 17/34A 250W 35-160hfe 25MHz $3.00
    2ST5949 NPN to-3 250V, 17/34A 250W 35-160hfe 25MHz $3.00


    mouser.com
    511-2ST2121 PNP to-3 250V, 17/34A 250W 35-160hfe 25MHz $3.79
    511-2ST5949 NPN to-3 250V, 17/34A 250W 35-160hfe 25MHz $5.14
    digikey.com
    497-8739-ND 2ST2121 PNP to-3 250V, 17/34A 250W 35-160hfe 25MHz $3.79
    497-6953-ND 2ST5949 NPN to-3 250V, 17/34A 250W 35-160hfe 25MHz not available

    these ON-Semi devices are much slower, at 4 mhz:
    mouser.com
    863-MJ21193G pnp to-3 250v 16/30A 250W 8-75hfe 4mhz $4.07
    863-MJ21194G npn to-3 250v 16/30A 250W 8-75hfe 4mhz $4.07
    digikey.com
    MJ21193GOS-ND pnp to-3 250v 16/30A 250W 8-75hfe 4mhz $4.56
    MJ21194GOS-ND npn to-3 250v 16/30A 250W 8-75hfe 4mhz $4.56

    either way, you will need to scope it to check for stability with the substitution.

    The driver stages (q10,q12 / q11,q13 in darlington configuration ) DO have 56 pf of negative feedback caps collector to base to control the high frequency gain, so if I were working on one, I would do one channel with the 4mhz transistors and the other with the 25 mhz transistors. Then test the daylights out of it on a scope, distortion analyzer and other instruments to figure out which to use.

    as a guide, pioneer does spec the amp with a frequency response of 5hz to 200,000 hz +0 / -1 db (distortion and power for THIS not specified)
    with 0.008% distortion at 60w (5 to 30,000 hz)
    and 0.01% distortion at 120w into 8 ohms (0.02% into 4 ohms at 20,000 hz)
     
  4. McMarantz

    McMarantz Active Member

    Messages:
    114
    Location:
    TURKEY
    Thanks Mark for INFO !
     
  5. darkhawk22

    darkhawk22 New Member

    Messages:
    29
    Location:
    Acworth, GA
    Reviving this thread to see if there are any other alternatives to these? Mark any ideas? My amp is working great but wouldn't mind having some for any future issues.
     

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