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The fisher 250TX with a power supply overheating transistor

Discussion in 'Fisher' started by havols, May 8, 2016.

  1. havols

    havols Active Member

    Messages:
    229
    Location:
    Manaus, Brazil
    Fred and Larry
    Thank you for your help in repairing the 250tx.
    I am using it enough.
    It has 2 non-original output transistors (channel R)
    I have here one fisher TX 50. I believe that the output transistors of this TX50 are the same 250TX. Can I remove the TX50 output transistors and use in output of 250TX?
    Thank you
     

     

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  2. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

    Messages:
    21,824
    Location:
    Glen Burnie Md.
    MAYBE! I ran the output #'s thru the NTE xref and got the same #'s. The problem with NTE is that they x-ref a whole range of parts with one. AndNTE just rebadges their parts so you have no idea what you areactually getting and who actually made it. Chances are that they are Chinese fakes is high. With FISHER using proprietary part numbers on their transistors it's very hard to find the actual specs for each part #. At least I haven't found one.

    The problem is that the TX-50 is rated for 16watts and the 250-TX is rated for approx 30-32 watts. So it's highly probable that you can swap the 250TX transistors into the TX-50 and they will work and loaf along. Going the other way, TX50 to 250TX the transistors would possibly be overloaded.


    TX-50
    TR1036-1 (pnp) NTE # 183
    TR1037-1 (npn) NTE # 182

    250tx
    TR02058-5 (pnp) NTE # 183
    TR01058-5 (npn) NTE # 182

    For Either unit. NPN use KSC2690AYS ($0.50ea @ mouser ) and for PNP KSA1220AYS ($0.45ea @ mouser) These are heavier duty than the NTE's and are made by FAIRCHILD. Let me check my stash and see if I have some to spare.
     
  3. fred soop

    fred soop Super Member

    Messages:
    1,991
    Alternately, use an insulated clip lead and connect it to the point to be checked. Now, you can look at the meter without being distracted by having to keep looking at the probe and the possibility that the probe will move when you look back at the meter.
     
  4. havols

    havols Active Member

    Messages:
    229
    Location:
    Manaus, Brazil
    For Either unit. NPN use KSC2690AYS ($0.50ea @ mouser ) and for PNP KSA1220AYS ($0.45ea @ mouser) These are heavier duty than the NTE's and are made by FAIRCHILD. Let me check my stash and see if I have some to spare

    Larry
    So, Can i replace the power output transistor from my Fisher 250TX (npn TR01058 & pnp TR02058) by:
    npn KSC2690A-Y from Fairchild
    pnp KSC1220A-Y from Fairchild;

    or
    npn MJE3055 from Motorola
    pnp MJE2955 from Motorola;

    You agree?
    Regards
     
  5. havols

    havols Active Member

    Messages:
    229
    Location:
    Manaus, Brazil
    Can i use a motorola MJE 15032 and MJE15033 as output transistor equivalent too? replacing 01058 and 02058?
    Regards
     
  6. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

    Messages:
    21,824
    Location:
    Glen Burnie Md.
    I would say probably ok. Compare the specs of the Fairchilds and the Motorola's.
     

     

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  7. fred soop

    fred soop Super Member

    Messages:
    1,991
    MJExxxxx are usually drivers, not outputs. Outputs would be MJ(no E)xxxxx.
     
  8. havols

    havols Active Member

    Messages:
    229
    Location:
    Manaus, Brazil
    Thanks larry and fred
    Is hard to find some good transistors here.
    I have replaced one pair of the output transistors 01058 and 02058 (TO127) by ST brand TIP3055 and TIP2955. I think that is a low quality transistor.

    I found here a C2690A-Y from fairchild. Maybe can i find a C1220A-Y from fairchild too. this pair can be a good substitutes to originals 01058 and 02058?

    I just can find a MJExxxx series.

    is there any other couple of good transistors that I can use as substitutes for 01058 and 02058? My 250TX have one pair original, and other TIPs ST brand.
    Regards, and thanks
     
  9. fred soop

    fred soop Super Member

    Messages:
    1,991
    TIP2955 and TIP3055 are rated at 60 volts. You have 64 volts rail to rail and with high line voltage, that could be higher. These transistors will work but you will not be able to drive the amplifier to maximum power where the output rail peaks close to the supply voltage.
     
  10. havols

    havols Active Member

    Messages:
    229
    Location:
    Manaus, Brazil
    OK fred.
    I'll replace them as soon as possible.
    Thank you very much.
     

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