Help: If I use a regular t6.3A fuse in a spot that expects a slo-blow fuse, will it work?

Discussion in 'The Workbench' started by Force235, Nov 28, 2020.

  1. Force235

    Force235 Well-Known Member

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    WIll it work?
     
  2. anitoli

    anitoli Well-Known Member Gold Supporting Member

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    You need a heater fuse for a 6100?
     
  3. Micky

    Micky Well-Known Member VIP Member

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    Briefly
     
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  4. Chris-in-LA

    Chris-in-LA Well-Known Member

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    Isn’t a fuse with a “t” a slo-blow?
     
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  5. thetragichero

    thetragichero Well-Known Member

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    please use the fuse the amp calls for
     
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  6. Gunner64

    Gunner64 Emotional Support Animal Gold Supporting Member

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    You are correct..T means timed, as in slo blow. Any fuse I have ever seen with a T in the prefix is a slo blow fuse.
     
  7. Force235

    Force235 Well-Known Member

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    Thanks, a fuse is not a fuse, is not a fuse, I ordered some better quality fuses to make sure the supposed slo-blo I'm using is really a "timed" fuse. The fuse I'm using, works for a few days then blows, it says its a T, but just looks like a regular single filament fuse.
    This is for my JTM-60
     
  8. Gunner64

    Gunner64 Emotional Support Animal Gold Supporting Member

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    If the fuse says T it's a slo blow. Perhaps your heaters are drawing too much current for some reason, I assume it was working for some time before it blew that fuse, why did it blow to begin with, with the original fuse?..that may be indicating a problem in the circuit itself. I have never worked on the jtm 60 so I don't have experience with it, or the schematic handy, but amps I have worked on that repeatedly blew heater fuses had rectifed heaters, and failing bridge rectifiers..not saying that's your issue here, but it may not be just a fuse problem.
     
  9. thetragichero

    thetragichero Well-Known Member

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    heater rectifier is a common point of failure (among many others) of that series. usually leaves behind a nice scorch mark on the board when the underspeced rectifier bites the bullet
     
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  10. Force235

    Force235 Well-Known Member

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    Bridge rectifier tests out good, even removed it and tested it. The original fuse lasted 25 years, then it died. I replaced it with a fuse I got from a cheap fuse kit from Amazon (China), I am suspect of the quality of the fuse, so I just ordered some higher (hopefully) quality fuses.
     
  11. Chris-in-LA

    Chris-in-LA Well-Known Member

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    Good luck, hope that fixes it.
     
  12. Ken Underwood

    Ken Underwood Well-Known Member VIP Member

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    Testing a bridge rectifier cold will not prove your point, if you are not sure replace it, with the correct type of course.
     
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  13. pedecamp

    pedecamp Well-Known Member

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    You have the ohms set right on the amp? Put a meter on your cab to verify what it is. Wrong ohms will pop a fuse eventually even if its the right fuse.
     
  14. Force235

    Force235 Well-Known Member

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    Yes, I tested the bridge rectifier in and out of the amp, tested good, but I might replace if it keeps blowing fuses. The speaker is correct, fyi.
     
  15. Force235

    Force235 Well-Known Member

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    Can I assume it wouldn't hurt to use a slo-blo (same rating) in a position that only needs a regular fuse?
     
  16. thetragichero

    thetragichero Well-Known Member

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    won't hurt the fuse but will likely hurt the amp
    you may wish to find yourself a good local tech because you seem bound and determined to damage your amps
     
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  17. Force235

    Force235 Well-Known Member

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    Definitely bound and determined to look into it myself - carefully... Last question was dumb agreed...
     
  18. anitoli

    anitoli Well-Known Member Gold Supporting Member

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    Can't find a good gut pic but does that use spade connectors in the heater string?
     
  19. myersbw

    myersbw Well-Known Member

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    Referencing the JTM60/600 schematic, measure R142 & R143 (100ohm balancing resistors)...and this is a 20-25 year old amp? If around that timeframe, take an LCR meter to C134, C135, C143, C144...large deviations in a reading indicate they likely need replaced. Look for typical cap swelling, etc. Might be causing a bit of extra current pull. ?
     
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  20. Force235

    Force235 Well-Known Member

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    A, not sure what you mean but here is a good pic of the area in question, the fuse that keeps blowing is behind the large blue cap on the left. DURAN C0 Mechanical Design Review_r1.jpg
     
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