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9090db F2624 TR017 2SA733 substitute?

Discussion in 'Exclusively Sansui' started by Linehand, Jul 29, 2018.

  1. Linehand

    Linehand Member

    Messages:
    94
    Location:
    Los Angeles, CA
    Can anyone recommend an available replacement for this transistor? I've crossed it to several others, none a direct match, and not sure what measurements to prioritize for this application. Center collector configuration seems to make this one a little difficult...

    Thanks

    Paul
     

     

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  2. tnsilver

    tnsilver AK Subscriber Subscriber

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    KSA733C make sure it's the 'C' suffix version (collector in the middle).
    You may wanna use this:

    [​IMG]
     
  3. Hipocrates

    Hipocrates Anti-Muppet Subscriber

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  4. Linehand

    Linehand Member

    Messages:
    94
    Location:
    Los Angeles, CA
    So KSA733CGBU should be good, I was looking at all the data sheets for those and saw 1emitter 2base 3collector config, now I see where it says "C" suffix indicates center collector-

    Thanks again guys
     
  5. Hipocrates

    Hipocrates Anti-Muppet Subscriber

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    Tom, what would you use as 2SC984 sub?
     
  6. Linehand

    Linehand Member

    Messages:
    94
    Location:
    Los Angeles, CA
    This image would have saved about 4 hours of my life! haha I'm getting an education though

    I have in my cart 863-MJE15030G and 863-MJE15031G for TR11-TR14, would MJE15032G and STV-3HY be a better match? Do value changes at any specific transistor necessitate value adjustments at the others?

    Thanks

    Paul
     
    Last edited: Jul 29, 2018

     

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  7. tnsilver

    tnsilver AK Subscriber Subscriber

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    It's the single bottle neck transistor on the entire driver board. No real good replacement other than NOS Hitachi 2SC984 or newer versions that needs to have their case (body) isolated by, for example, encasing them in JBWeld or wrapping them in shrink. The newer versions have one of the pins (I think it's base) connected to the case. This will short with the driver transistor heat sink if not isolated.
    yes, and no. MJE15032G (NPN) and the complementary MJE15033G (PNP) have higher voltage (VCEO/VCBO) ratings. The STV-3H(Y) thermistor diode replaced the 2SC984 temp/co transistor in a later revision of the bias circuit on the F2624 driver amp PCB. You can't just swap the transistor for a diode.
     
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  8. Linehand

    Linehand Member

    Messages:
    94
    Location:
    Los Angeles, CA

    My mistake, I meant the to say MJE15032-33G vs MJE15030-31G rather than STV-H.

    I'll go with what you have indicated (32-33G)
     
    Last edited: Jul 29, 2018
  9. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    I believe you'll find it's the collector. :(

    I think the safest/best solution is to use a plastic case (TO-92) replacement, and modify the method of securing the device to the heatsink, i.e. use the 'flat' of the TO-92 to the heatsink.
     
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  10. Linehand

    Linehand Member

    Messages:
    94
    Location:
    Los Angeles, CA
    I subbed KSC2383 for 2SC984 and I could only get 1-6mA max across F04 . Swapped orig 2SC984 from other side, problem solved.

    My best guess is Collector/Base voltage is too high on that one. Emitter/Base is close to original and you would think that would be the only real factor...
     
  11. Linehand

    Linehand Member

    Messages:
    94
    Location:
    Los Angeles, CA

    Here's what I did for 2SC984. I'm not certain how this will turn out.

    I used KSC1845 and the design is based on Tnsilver suggestion (which after a two week crash course, I now understand haha) not sure its what you had in mind, but if its out there I haven't seen it...

    Disclaimer: My stereo won't be pushed too hard

    Been running thirty min since that pic and its ranging 27.10-27.81mA


    IMG_1800.jpg

    Resistor lead is close to transistor leg...

    IMG_1801.jpg

    IMG_1804.jpg
    IMG_1805.jpg

    Encased in JB Weld

    IMG_1807.jpg

    IMG_1808.jpg

    IMG_1809.jpg
     
    Last edited: Aug 11, 2018
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  12. tnsilver

    tnsilver AK Subscriber Subscriber

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    Nice!!! Keep monitoring and let us know. I might do the same for my 9090 F2436 driver amp bias circuit, as the stock 2SC984 are starting to act up funny.
     
  13. Linehand

    Linehand Member

    Messages:
    94
    Location:
    Los Angeles, CA
    So, I set bias at 30 +/- 1mA following the procedure you outlined - thanks for writing that up btw.

    Ran at low/medium listening volume, transient peaks tapping just above 1w on the meters for 25 min

    Results:

    Right Channel (KSC1845)
    Bias 1 min after shutdown: 37.5mA
    Bias after 20 min: 31.77mA

    Left Channel (2SC984)
    Bias 1 min after shutdown: 35.4mA
    Bias after 20 min: 30.30mA

    So its easy to get OCD on this measurement and if you do, its best to set late night when voltage at the meter is most stable. The bias dropped then rose up 5 mA when the AC kicked on...

    Also, meant to thank Hyperion for the TO-92 suggestion
     
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  14. tnsilver

    tnsilver AK Subscriber Subscriber

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    Good! Looks like it's working. Should be stabilized after 20 minutes, but bias drops real fast on shutdown. Could the post shutdown reading be a meter memory thing (min/max)?
     
  15. Linehand

    Linehand Member

    Messages:
    94
    Location:
    Los Angeles, CA
    So the way I wrote that data is a little confusing. What I meant to say was I played the stereo until nice and warm, then shut it down, waited 1 min, then switched it back on. The '1 min after shutdown' reading is where the meter topped out before beginning to drop back down. I wanted to see how TR09 and TR10 interact warm vs cold.

    I ran more specific timed tests and they are pretty close. This was from a dead cold start on different nights. AC was on and off which makes this a "real world test", at least for me anyway...

    Left (2SC984):

    43.00 mA @ 01 min
    36.60 mA @ 05 min
    28.55 mA @ 10 min
    31.42 mA @ 15 min
    36.98 mA @ 30 min

    Right (KSC1845)

    40.48 @ 01 min
    35.43 @ 05 min
    35.70 @ 10 min
    29.80 @ 15 min
    38.50 @ 30 min

    I'm actually pretty stoked at how close they are. The only issue I see now is how it will react if pushed hard. Do we know how critical the thermal interaction is between TR09-10 and TR13-14 is? Is TR09-10 meant to react differently with temp increase?

    My Spendors are such and easy load this beast doesn't even feel it...
     

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