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Thread: MOSFET Help...

  1. #1
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    Default MOSFET Help...

    I have two mosfet's in a switching PS that have decided to have a meltdown. They are part number IXTH24N50's

    Here is the datasheet...
    http://pdf1.alldatasheet.com/datashe...IXTH24N50.html

    I'm having a hard time finding these. Can anyone suggest a drop in replacement?
    Thanks!
    Adam

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    Quote Originally Posted by 300EVIL View Post
    I have two mosfet's in a switching PS that have decided to have a meltdown. They are part number IXTH24N50's

    Here is the datasheet...
    http://pdf1.alldatasheet.com/datashe...IXTH24N50.html

    I'm having a hard time finding these. Can anyone suggest a drop in replacement?
    Thanks!
    Adam
    i could have sworn newarks site said they had nine in stock - now there're 7 - coincidence?

  3. #3
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    Quote Originally Posted by laserist View Post
    i could have sworn newarks site said they had nine in stock - now there're 7 - coincidence?
    Ah! Just what I needed... Thank you!

    http://www.newark.com/ixys-semicondu...?Ntt=IXTH24N50

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    Default

    This website is usually my first port of call:

    http://www.findchips.com/
    KVANT Australian projector sales
    https://www.facebook.com/kvantaus/

    Lasershowparts- Laser Parts at great prices
    https://www.facebook.com/lasershowparts/

  5. #5
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    Quote Originally Posted by dave View Post
    This website is usually my first port of call:

    http://www.findchips.com/
    Nice site! thanks Dave!

  6. #6
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    If those go in what I think they go in, immediately replace the fast diode thing in the To220 pack on the heatsink, possibly the to-92 cased npn/pnp pairs and zeners in the gate circuits, and the HV electrolytic cap just down stream of the fets next to the heat sink. They all tend to go at once or be stressed. Then you need the adjust procedure for the pots, including the noise and duty cycle pots.Use a LOW ESR power supply grade lytic, like a photoflash cap. The procedure involves looking at the gate drive with a scope on a isolation transformer.

    If you pop more then one set of new fets, you need to walk through the adjust.. I have the factory book on how to do it.

    Also look around on the motherboard for little green or blue things that look like 1% resistors, mostly to the left of the heatsink with the lid open and the heatsink setting away from you. They are fuses, and usually at least one of them goes with the FETS.

    Steve
    Last edited by mixedgas; 04-28-2010 at 19:04.
    Qui habet Christos, habet Vitam!
    I should have rented the space under my name for advertising.
    When I still could have...

  7. #7
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    Quote Originally Posted by mixedgas View Post
    If those go in what I think they go in, immediately replace the fast diode thing in the To220 pack on the heatsink, possibly the to-92 cased npn/pnp pairs and zeners in the gate circuits, and the HV electrolytic cap just down stream of the fets next to the heat sink. They all tend to go at once or be stressed. Then you need the adjust procedure for the pots, including the noise and duty cycle pots.Use a LOW ESR power supply grade lytic, like a photoflash cap. The procedure involves looking at the gate drive with a scope on a isolation transformer.

    If you pop more then one set of new fets, you need to walk through the adjust.. I have the factory book on how to do it.

    Also look around on the motherboard for little green or blue things that look like 1% resistors, mostly to the left of the heatsink with the lid open and the heatsink setting away from you. They are fuses, and usually at least one of them goes with the FETS.

    Steve
    Wow............................

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    Quote Originally Posted by laserist View Post
    Wow............................
    Yeah, Steve is a walking database.

    The PS is the main switcher board in a Melles Griot high output DPSS laser.

    One of these...


    Steve,
    I checked the fast diodes and they test good but I guess they may still be shot. I do plan on replacing the zeners and the transistors in the gate circuits just because they are cheap enough. I checked the cap and it seems to be okay but I don't have an ESR tester so I'll probably replace it too.

    Thanks for the tip on the pico fuses, I'll check those out as well. I'm hoping to fix this as I'd hate to blow $30 in new FET's. I do plan on running a 100W bulb in series during the first test.
    Thanks!
    Adam

  9. #9
    mixedgas's Avatar
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    Steve now has learned something. Melles stocked the 24Nxx for the 150R air cooled psu. I had NO idea they were in a solid state, too

    Disregard the part about the HV lytic and the noise gate.

    Maxima Mea Culpa.

    Steve
    Qui habet Christos, habet Vitam!
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  10. #10
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    Quote Originally Posted by mixedgas View Post
    Steve now has learned something. Melles stocked the 24Nxx for the 150R air cooled psu. I had NO idea they were in a solid state, too

    Disregard the part about the HV lytic and the noise gate.

    Maxima Mea Culpa.

    Steve
    Hey Steve,
    I was surprised to find ion grade FET's in a DPSS power supply as well. Although, the diode and TEC together draw almost 40A at full power.

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