output transistors?

Archived from groups: rec.audio.pro (More info?)

I have an old Hafler amp that blew a side. It uses MOSFET transistors I cant
find.
These are in shiny round cans with two wire leads sticking down, and they
screw onto little plastic sheets.
I have a bunch of car radio outputs that look like they will screw down.

Will they work, or will they hurt anything?
36 answers Last reply
More about output transistors
  1. Archived from groups: rec.audio.pro (More info?)

    > I have an old Hafler amp that blew a side. It uses
    > MOSFET transistors I cant find.

    Hafler MOSFETs sometimes show up on eBay.
  2. Archived from groups: rec.audio.pro (More info?)

    "Sugarite" <not for you> wrote in message
    news:pP6dnfiq-5xdyb7cRVn-jg@giganews.com

    > I have an old Hafler amp that blew a side. It uses MOSFET transistors
    > I cant find.

    If you flog some Haffler enthusiast sites and/or contact Hafler, you can
    obtain some wisdom about modern replacements.

    > These are in shiny round cans with two wire leads sticking down, and
    > they screw onto little plastic sheets.

    Power transistors mounted on circuit boards.

    > I have a bunch of car radio outputs that look like they will screw
    > down.

    Unlikely that they are MOSFETs, unlikely that they could handle the voltage
    in an a large audio power amp, even if they were.

    > Will they work,

    Highly unlikely.

    >or will they hurt anything?

    Highly likely.

    Fixing power amps isn't like changing spark plugs in a car. Get competent
    help!
  3. Archived from groups: rec.audio.pro (More info?)

    In article <pP6dnfiq-5xdyb7cRVn-jg@giganews.com>, Sugarite <not for you> wrote:
    >I have an old Hafler amp that blew a side. It uses MOSFET transistors I cant
    >find.
    >These are in shiny round cans with two wire leads sticking down, and they
    >screw onto little plastic sheets.
    >I have a bunch of car radio outputs that look like they will screw down.
    >
    >Will they work, or will they hurt anything?

    I'm sorry, this is not funny. This is not funny at all. What have you
    done with the real Sugarite?
    --scott
    --
    "C'est un Nagra. C'est suisse, et tres, tres precis."
  4. Archived from groups: rec.audio.pro (More info?)

    "Scott Dorsey" <kludge@panix.com> wrote in message
    news:cfvlf2$sli$1@panix2.panix.com...
    > In article <pP6dnfiq-5xdyb7cRVn-jg@giganews.com>, Sugarite <not for you>
    wrote:
    > >I have an old Hafler amp that blew a side. It uses MOSFET transistors I
    cant
    > >find.
    > >These are in shiny round cans with two wire leads sticking down, and they
    > >screw onto little plastic sheets.
    > >I have a bunch of car radio outputs that look like they will screw down.
    > >
    > >Will they work, or will they hurt anything?
    >
    > I'm sorry, this is not funny. This is not funny at all. What have you
    > done with the real Sugarite?
    > --scott
    > --
    > "C'est un Nagra. C'est suisse, et tres, tres precis."

    I thought maybe some auto radios used MOSFETs.
    Please don't get on me for it.
  5. Archived from groups: rec.audio.pro (More info?)

    In article <nOydnfqykM0gnrncRVn-gQ@giganews.com>, Sugarite <not for you> wrote:
    >
    >I thought maybe some auto radios used MOSFETs.
    >Please don't get on me for it.

    Maybe, but if you don't say what model amplifier you have, and you don't
    say what model transistors you have, how can ANYONE expect to even make
    a GUESS that they might work. What have you done with the real Sugarite?
    --scott
    --
    "C'est un Nagra. C'est suisse, et tres, tres precis."
  6. Archived from groups: rec.audio.pro (More info?)

    "Sugarite" <not for you> wrote in message
    news:pP6dnfiq-5xdyb7cRVn-jg@giganews.com...

    > I have an old Hafler amp that blew a side. It uses MOSFET transistors I
    cant
    > find.
    > These are in shiny round cans with two wire leads sticking down, and they
    > screw onto little plastic sheets.
    > I have a bunch of car radio outputs that look like they will screw down.
    >


    ** You need some Hitachi mosfets - probably types 2SJ50 and 2SK135.

    No normal transistor can be substited.


    ............ Phil
  7. Archived from groups: rec.audio.pro (More info?)

    Phil Allison wrote:

    > "Sugarite" <not for you> wrote in message
    > news:pP6dnfiq-5xdyb7cRVn-jg@giganews.com...
    >
    > > I have an old Hafler amp that blew a side. It uses MOSFET transistors I
    > cant
    > > find.
    > > These are in shiny round cans with two wire leads sticking down, and they
    > > screw onto little plastic sheets.
    > > I have a bunch of car radio outputs that look like they will screw down.
    > >
    >
    > ** You need some Hitachi mosfets - probably types 2SJ50 and 2SK135.
    >
    > No normal transistor can be substited.

    You omit to mention that Hitachi no longer make them.

    Close equivalents are available from Semelab and Exicon.


    Graham
  8. Archived from groups: rec.audio.pro (More info?)

    "Pooh Bear" <rabbitsfriendsandrelations@hotmail.com> wrote in message
    news:4123AF6A.CF8082B7@hotmail.com...
    > You omit to mention that Hitachi no longer make them.
    >
    > Close equivalents are available from Semelab and Exicon.

    ....and available from ProfusionPLC, a UK company but ship very efficiently
    to the USA as well.

    If the output MOSFETs are blown, then the drivers may well also be blown.
    So might the gate resistors.
  9. Archived from groups: rec.audio.pro (More info?)

    Walter Harley wrote:

    > "Pooh Bear" <rabbitsfriendsandrelations@hotmail.com> wrote in message
    > news:4123AF6A.CF8082B7@hotmail.com...
    > > You omit to mention that Hitachi no longer make them.
    > >
    > > Close equivalents are available from Semelab and Exicon.
    >
    > ...and available from ProfusionPLC, a UK company but ship very efficiently
    > to the USA as well.

    Oh good ! I know them but wasn't sure if they serviced the US market
    effectively.

    Profusion are a decent company to deal with.


    > If the output MOSFETs are blown, then the drivers may well also be blown.
    > So might the gate resistors.

    I'll beg to differ. That would be a rare condition IMHO.

    Hitachi (including other manufactuer similar style ) mosfets usually fail
    open-circuit without destructive behaviour.


    Graham ( designed quite a few mosfet amps )
  10. Archived from groups: rec.audio.pro (More info?)

    Pooh Bear <rabbitsfriendsandrelations@hotmail.com> wrote:
    >
    >> If the output MOSFETs are blown, then the drivers may well also be blown.
    >> So might the gate resistors.
    >
    >I'll beg to differ. That would be a rare condition IMHO.
    >
    >Hitachi (including other manufactuer similar style ) mosfets usually fail
    >open-circuit without destructive behaviour.

    Right, but often blown output devices are a symptom of something else gone
    wrong farther up the chain, rather than the original problem. Gate resistors
    gone open will take the output stage out with oscillation sometimes, for
    example.
    --scott

    --
    "C'est un Nagra. C'est suisse, et tres, tres precis."
  11. Archived from groups: rec.audio.pro (More info?)

    Scott Dorsey wrote:

    > Pooh Bear <rabbitsfriendsandrelations@hotmail.com> wrote:
    > >
    > >> If the output MOSFETs are blown, then the drivers may well also be blown.
    > >> So might the gate resistors.
    > >
    > >I'll beg to differ. That would be a rare condition IMHO.
    > >
    > >Hitachi (including other manufactuer similar style ) mosfets usually fail
    > >open-circuit without destructive behaviour.
    >
    > Right, but often blown output devices are a symptom of something else gone
    > wrong farther up the chain, rather than the original problem. Gate resistors
    > gone open will take the output stage out with oscillation sometimes, for
    > example.

    My own experience has been mainly with failed devices due to overtemperature ( on
    C Audio amplifiers that have marginal cooling for example ).

    C Audio used to consider the failed devices as *normal* !

    They also had poor lifetime on the PSU electrolytics as they stood in the path of
    the searing heat from the fan cooling !

    Replacement of either / both was considered normal service / repair !

    Harman bought C Audio a number of years ago in a classic Harman move that left
    the staff that knew the product in Cambridge UK unemployed whilst moving the
    inventory to the Soundcraft site some 40 miles south approx.

    A friend of mine who worked for Harman UK said at the time that they had a pile
    of bits that they had no idea what to do with !

    C Audio had just introduced the rather poor GB bipolar series. This eventually
    ended up rebadged as the Crown CE series ! Nuff said ?

    Does Harman have a death wish ?


    Graham
  12. Archived from groups: rec.audio.pro (More info?)

    "Pooh Bear" <rabbitsfriendsandrelations@hotmail.com> wrote in message
    news:412408FD.2EEEE5FB@hotmail.com...
    > Oh good ! I know them but wasn't sure if they serviced the US market
    > effectively.

    Very much so. In fact, when I've ordered from them, shipping has been both
    cheaper and faster than from most of the US companies I deal with - and I'm
    on the west coast. Quite remarkable.


    >> If the output MOSFETs are blown, then the drivers may well also be blown.
    >> So might the gate resistors.
    >
    > I'll beg to differ. That would be a rare condition IMHO.
    >
    > Hitachi (including other manufactuer similar style ) mosfets usually fail
    > open-circuit without destructive behaviour.

    Our experience differs in that regard, evidently. I would say that the
    majority of the MOSFET amps I've fixed have failed short-circuit and about
    half have taken out the drivers.

    Oscillation might have been the cause in some, but I think not all.
  13. Archived from groups: rec.audio.pro (More info?)

    "Pooh Bear" <rabbitsfriendsandrelations@hotmail.com> wrote in message
    news:412419E7.7EE4794E@hotmail.com

    > Does Harman have a death wish ?

    They do a lot of OEM business in Detoit, or at least they did. Similar
    questions are heard around town.
  14. Archived from groups: rec.audio.pro (More info?)

    Arny Krueger <arnyk@hotpop.com> wrote:
    >"Pooh Bear" <rabbitsfriendsandrelations@hotmail.com> wrote in message
    >news:412419E7.7EE4794E@hotmail.com
    >
    >> Does Harman have a death wish ?
    >
    >They do a lot of OEM business in Detoit, or at least they did. Similar
    >questions are heard around town.

    Harman doesn't need customers. They have investors. Soon they will own
    everything in the industry that isn't already owned by EVI.
    --scott
    --
    "C'est un Nagra. C'est suisse, et tres, tres precis."
  15. Archived from groups: rec.audio.pro (More info?)

    Pooh Bear <rabbitsfriendsandrelations@hotmail.com> wrote:
    >Phil Allison wrote:
    >>
    >> ** You need some Hitachi mosfets - probably types 2SJ50 and 2SK135.
    >>
    >> No normal transistor can be substited.
    >
    >You omit to mention that Hitachi no longer make them.
    >
    >Close equivalents are available from Semelab and Exicon.

    In TO-3 packages, or do you have to side mount TO-3Ps in there?
    --scott

    --
    "C'est un Nagra. C'est suisse, et tres, tres precis."
  16. Archived from groups: rec.audio.pro (More info?)

    "Scott Dorsey" <kludge@panix.com> wrote in message
    news:cg2622$kp9$1@panix2.panix.com
    > Arny Krueger <arnyk@hotpop.com> wrote:
    >> "Pooh Bear" <rabbitsfriendsandrelations@hotmail.com> wrote in message
    >> news:412419E7.7EE4794E@hotmail.com
    >>
    >>> Does Harman have a death wish ?
    >>
    >> They do a lot of OEM business in Detoit, or at least they did.
    >> Similar questions are heard around town.
    >
    > Harman doesn't need customers. They have investors. Soon they will
    > own everything in the industry that isn't already owned by EVI.

    ...or Bose.

    Recoton was about as close as they ever had to competition, and now they are
    being broken up.
  17. Archived from groups: rec.audio.pro (More info?)

    "Scott Dorsey"
    > Pooh Bear :
    > >
    > >> If the output MOSFETs are blown, then the drivers may well also be
    blown.
    > >> So might the gate resistors.
    > >
    > >I'll beg to differ. That would be a rare condition IMHO.
    > >
    > >Hitachi (including other manufactuer similar style ) mosfets usually fail
    > >open-circuit without destructive behaviour.
    >
    > Right, but often blown output devices are a symptom of something else gone
    > wrong farther up the chain, rather than the original problem. Gate
    resistors
    > gone open will take the output stage out with oscillation sometimes, for
    > example.


    ** Open gate resistors ???

    Such is the logic of a failed recorder mechanic and electronics charlatan.


    ............... Phil
  18. Archived from groups: rec.audio.pro (More info?)

    "Scott Dorsey" <kludge@panix.com> wrote in message
    news:cg283a$fq2$1@panix2.panix.com...
    > In TO-3 packages, or do you have to side mount TO-3Ps in there?

    The Exicon lateral MOSFETs sold by ProfusionPLC are TO-3; direct drop-in
    replacement.

    Prices seem to run in the vicinity of US$10-20, more or less depending on
    the part. I don't remember which models are the equivalent to the
    2SK135/2SJ50.
  19. Archived from groups: rec.audio.pro (More info?)

    "Walter Harley".
    > "Pooh Bear"
    >
    > >> If the output MOSFETs are blown, then the drivers may well also be
    blown.
    > >> So might the gate resistors.
    > >
    > > I'll beg to differ. That would be a rare condition IMHO.
    > >
    > > Hitachi (including other manufactuer similar style ) mosfets usually
    fail
    > > open-circuit without destructive behaviour.
    >
    > Our experience differs in that regard, evidently. I would say that the
    > majority of the MOSFET amps I've fixed have failed short-circuit and about
    > half have taken out the drivers.


    ** The subject is Hitachi ( lateral) mosfets - in *** TO3 *** package
    ( 2SK135, 2SJ50 etc)

    Other types are NOT the same.

    Other packages do not have fusible wire links inside.

    The common IRF ... switching types fail short.


    >
    > Oscillation might have been the cause in some, but I think not all.
    >

    ** Hitachi lateral mosfets do not fail from oscillations.

    The Zobel network may be toast but the mosfets are always fine.


    ............ Phil
  20. Archived from groups: rec.audio.pro (More info?)

    Scott Dorsey wrote:

    > Pooh Bear <rabbitsfriendsandrelations@hotmail.com> wrote:
    > >Phil Allison wrote:
    > >>
    > >> ** You need some Hitachi mosfets - probably types 2SJ50 and 2SK135.
    > >>
    > >> No normal transistor can be substited.
    > >
    > >You omit to mention that Hitachi no longer make them.
    > >
    > >Close equivalents are available from Semelab and Exicon.
    >
    > In TO-3 packages, or do you have to side mount TO-3Ps in there?

    TO-3 no problem.

    Never really understood why Hitachi dropped the TO-3s - many UK pro amp
    manufacturers used them for sure.


    Graham
  21. Archived from groups: rec.audio.pro (More info?)

    "Pooh Bear" <rabbitsfriendsandrelations@hotmail.com> wrote in message
    news:4124F888.F427A350@hotmail.com
    > Scott Dorsey wrote:
    >
    >> Pooh Bear <rabbitsfriendsandrelations@hotmail.com> wrote:
    >>> Phil Allison wrote:
    >>>>
    >>>> ** You need some Hitachi mosfets - probably types 2SJ50 and
    >>>> 2SK135.
    >>>>
    >>>> No normal transistor can be substited.
    >>>
    >>> You omit to mention that Hitachi no longer make them.
    >>>
    >>> Close equivalents are available from Semelab and Exicon.
    >>
    >> In TO-3 packages, or do you have to side mount TO-3Ps in there?
    >
    > TO-3 no problem.
    >
    > Never really understood why Hitachi dropped the TO-3s - many UK pro
    > amp manufacturers used them for sure.
    >

    "The future is plastic".
  22. Archived from groups: rec.audio.pro (More info?)

    Pooh Bear <rabbitsfriendsandrelations@hotmail.com> wrote:
    >
    >TO-3 no problem.
    >
    >Never really understood why Hitachi dropped the TO-3s - many UK pro amp
    >manufacturers used them for sure.

    Everybody is dropping TO-3 packages for everything, because they are
    expensive to make, and if all you care about is peak power capability
    it doesn't buy you all that much over the flat packs. The TO-3 is a big
    deal for linear applications with high average power needs, but who does
    THAT stuff any more in the modern digital world but a few audio guys?
    --scott

    --
    "C'est un Nagra. C'est suisse, et tres, tres precis."
  23. Archived from groups: rec.audio.pro (More info?)

    "Pooh Bear" <rabbitsfriendsandrelations@hotmail.com> wrote in message
    news:4124F888.F427A350@hotmail.com...
    > Never really understood why Hitachi dropped the TO-3s - many UK pro amp
    > manufacturers used them for sure.

    TO-3 package is awkward for assembly - has to go on the other side of the
    heat sink from the wires. One heck of a lot easier to just solder a TO3P or
    whatever onto the PCB, and then screw it or clamp it to the heat sink in
    final assembly. And the junction-to-case thermal resistance of TO-3 is
    *higher* (worse) than TO-263, at least based on looking at a couple of
    haphazardly chosen datasheets just now. So it's not obvious why any
    manufacturer would prefer a TO-3 over a more modern package.

    About the only thing TO-3 has going for it is that it's easier to socket for
    repair. The value of that, these days, should be self-evident :-(

    Something to consider is that old slow low-beta bipolar power Q's like
    2N3055 didn't have stability problems with long leads, so it wasn't a big
    problem to run wires from the PCB to the socket. But modern MOSFETs aren't
    happy with a bunch of inductance (like a couple inches of wire) connected to
    the gate.
  24. Archived from groups: rec.audio.pro (More info?)

    "Scott Dorsey"
    > Pooh Bear
    > >Phil Allison wrote:
    > >>
    > >> ** You need some Hitachi mosfets - probably types 2SJ50 and 2SK135.
    > >>
    > >> No normal transistor can be substitute.
    > >
    > >You omit to mention that Hitachi no longer make them.
    > >
    > >Close equivalents are available from Semelab and Exicon.
    >
    > In TO-3 packages, or do you have to side mount TO-3Ps in there?


    ** Too lazy to do a simple Google search are we now, Dorsey - rather
    have a mid air debate instead ???

    See : http://www.exicon.com/


    ............ Phil
  25. Archived from groups: rec.audio.pro (More info?)

    In article <2ojnv7Fb7ih4U2@uni-berlin.de>,
    Phil Allison <philallison@tpg.com.au> wrote:
    >
    >"Scott Dorsey"
    >> Pooh Bear
    >> >Phil Allison wrote:
    >> >>
    >> >> ** You need some Hitachi mosfets - probably types 2SJ50 and 2SK135.
    >> >>
    >> >> No normal transistor can be substitute.
    >> >
    >> >You omit to mention that Hitachi no longer make them.
    >> >
    >> >Close equivalents are available from Semelab and Exicon.
    >>
    >> In TO-3 packages, or do you have to side mount TO-3Ps in there?
    >
    >** Too lazy to do a simple Google search are we now, Dorsey - rather
    >have a mid air debate instead ???
    >
    > See : http://www.exicon.com/

    Sorry, Phil, I don't even have web access right now. I'm on the road.
    So, are these in TO-3 packages, or do I have to side-mount TO-3P types?
    --scott


    --
    "C'est un Nagra. C'est suisse, et tres, tres precis."
  26. Archived from groups: rec.audio.pro (More info?)

    Scott Dorsey wrote:

    > Pooh Bear <rabbitsfriendsandrelations@hotmail.com> wrote:
    > >
    > >TO-3 no problem.
    > >
    > >Never really understood why Hitachi dropped the TO-3s - many UK pro amp
    > >manufacturers used them for sure.
    >
    > Everybody is dropping TO-3 packages for everything, because they are
    > expensive to make, and if all you care about is peak power capability
    > it doesn't buy you all that much over the flat packs. The TO-3 is a big
    > deal for linear applications with high average power needs, but who does
    > THAT stuff any more in the modern digital world but a few audio guys?

    A colleague of mine has been convinced for years that Motorola and
    subsequently On Semi are about to drop TO-3. Hasn't happened yet.

    I guess there must be significant demand for them outside of audio. The TO-3
    can ( being hermetic ) allows the chip to run at a higher junction temp than
    plastic - so you can run higher dissipation / device.


    Graham
  27. Archived from groups: rec.audio.pro (More info?)

    Walter Harley wrote:

    > "Pooh Bear" <rabbitsfriendsandrelations@hotmail.com> wrote in message
    > news:4124F888.F427A350@hotmail.com...
    > > Never really understood why Hitachi dropped the TO-3s - many UK pro amp
    > > manufacturers used them for sure.
    >
    > TO-3 package is awkward for assembly - has to go on the other side of the
    > heat sink from the wires. One heck of a lot easier to just solder a TO3P or
    > whatever onto the PCB, and then screw it or clamp it to the heat sink in
    > final assembly. And the junction-to-case thermal resistance of TO-3 is
    > *higher* (worse) than TO-263, at least based on looking at a couple of
    > haphazardly chosen datasheets just now. So it's not obvious why any
    > manufacturer would prefer a TO-3 over a more modern package.
    >
    > About the only thing TO-3 has going for it is that it's easier to socket for
    > repair. The value of that, these days, should be self-evident :-(
    >
    > Something to consider is that old slow low-beta bipolar power Q's like
    > 2N3055 didn't have stability problems with long leads, so it wasn't a big
    > problem to run wires from the PCB to the socket. But modern MOSFETs aren't
    > happy with a bunch of inductance (like a couple inches of wire) connected to
    > the gate.

    There's a way of mounting TO-3 that's actually much simpler than any plastic
    device and has pretty much none of the disadvantages you mention. I've used it
    in many Studiomaster designs.

    Have the pcb fitted directly underneath the devices. Fit solderable studs to
    the pcb. Studs pass through the heatsink, aligning the assembly. TO-3 device
    drops onto the studs from the other side of the heatsink and bolts up - leads
    pass through into the pcb and are soldered. Perfectly self-aligning.

    In comparison, plastic devices invariably seem to need fiddling to get them to
    line up with their mounting holes before you can solder the leads.

    I prefer my method with the TO-3s.

    Incidentally, On Semi make MJ21193/4 in TO-3 and MJL21193/4 in TO-264 (
    presumably same chip ). Same thermal resistance but the plastic versions are
    more expensive !
    The TO-3 part also is rated at 250W instead of 200W on account of the higher
    allowable junction temp.

    Graham
  28. Archived from groups: rec.audio.pro (More info?)

    Stephen Sank wrote:

    > Hey, but at least selenium rectifiers never get dandruff.
    >
    > It is exceedingly rare, in my experience, for any old Hafler amp to fry any output devices.
    > About the only way to do it is to bypass the output & supply fuses, turn on the amp with the
    > spkr terminals shorted, and crank it up to full power with a 100kHz sqarewave for a few hours.
    > Joe Norris used to demonstrate the thermal control on the fan of a DH500 by shorting both spkr
    > lines & cranking it up to full power for a while, until the fan kicked up to high gear.
    > The later Haflers, post DH500/XL600, did use TO-3P package MOSFETs, some being the
    > 2SK1058/2SJwhatever

    2SJ192 IIRC

    > lateral types that were supposed to replace the 2SK134/135/176 &
    > 2SJ49/50/56 laterals, but were discontinued so quickly they're even harder to find the the old
    > TO-3 types. The majority of MOSFET's used in current audio are HEXFET types.

    They are ? For linear outputs as opposed to PWM ?


    Graham
  29. Archived from groups: rec.audio.pro (More info?)

    Pooh Bear <rabbitsfriendsandrelations@hotmail.com> wrote in
    news:41258DA5.FF5FAA68@hotmail.com:

    > Stephen Sank wrote:
    >
    >> Hey, but at least selenium rectifiers never get dandruff.
    >>
    >> It is exceedingly rare, in my experience, for any old Hafler amp to
    >> fry any output devices. About the only way to do it is to bypass the
    >> output & supply fuses, turn on the amp with the spkr terminals
    >> shorted, and crank it up to full power with a 100kHz sqarewave for a
    >> few hours. Joe Norris used to demonstrate the thermal control on the
    >> fan of a DH500 by shorting both spkr lines & cranking it up to full
    >> power for a while, until the fan kicked up to high gear. The later
    >> Haflers, post DH500/XL600, did use TO-3P package MOSFETs, some being
    >> the 2SK1058/2SJwhatever
    >
    > 2SJ192 IIRC
    >
    >> lateral types that were supposed to replace the 2SK134/135/176 &
    >> 2SJ49/50/56 laterals, but were discontinued so quickly they're even
    >> harder to find the the old TO-3 types. The majority of MOSFET's used
    >> in current audio are HEXFET types.
    >
    > They are ? For linear outputs as opposed to PWM ?

    Yup - The BSS EPC780 amps (commonly packaged with Turbosound
    Flashlight/Floodlight speakers)
    use IRF840/11P20 outputs (18 of each per channel)in a very conventional
    linear fashion.
    M
  30. Archived from groups: rec.audio.pro (More info?)

    "Scott Dorsey" <kludge@panix.com> wrote in message
    news:cg2d5j$6u5$1@panix2.panix.com...
    > In article <2ojnv7Fb7ih4U2@uni-berlin.de>,
    > Phil Allison <philallison@tpg.com.au> wrote:
    > >
    > >"Scott Dorsey"
    > >> Pooh Bear
    > >> >Phil Allison wrote:
    > >> >>
    > >> >> ** You need some Hitachi mosfets - probably types 2SJ50 and
    2SK135.
    > >> >>
    > >> >> No normal transistor can be substitute.
    > >> >
    > >> >You omit to mention that Hitachi no longer make them.
    > >> >
    > >> >Close equivalents are available from Semelab and Exicon.
    > >>
    > >> In TO-3 packages, or do you have to side mount TO-3Ps in there?
    > >
    > >** Too lazy to do a simple Google search are we now, Dorsey - rather
    > >have a mid air debate instead ???
    > >
    > > See : http://www.exicon.com/
    >
    > Sorry, Phil, I don't even have web access right now. I'm on the road.
    > So, are these in TO-3 packages, or do I have to side-mount TO-3P types?

    To-3

    although they also have To-3p versions available if you want ....
  31. Archived from groups: rec.audio.pro (More info?)

    "Sugarite" <not for you> wrote in message
    news:nOydnfqykM0gnrncRVn-gQ@giganews.com...
    >
    > "Scott Dorsey" <kludge@panix.com> wrote in message
    > news:cfvlf2$sli$1@panix2.panix.com...
    > > In article <pP6dnfiq-5xdyb7cRVn-jg@giganews.com>, Sugarite <not for you>
    > wrote:
    > > >I have an old Hafler amp that blew a side. It uses MOSFET transistors I
    > cant
    > > >find.
    > > >These are in shiny round cans with two wire leads sticking down, and
    they
    > > >screw onto little plastic sheets.
    > > >I have a bunch of car radio outputs that look like they will screw
    down.
    > > >
    > > >Will they work, or will they hurt anything?
    > >
    > > I'm sorry, this is not funny. This is not funny at all. What have you
    > > done with the real Sugarite?
    > > --scott
    > > --
    > > "C'est un Nagra. C'est suisse, et tres, tres precis."
    >
    > I thought maybe some auto radios used MOSFETs.
    > Please don't get on me for it.
    >

    Well yes they do - a lot of car Audio Amplifiers use variations of the D
    class output and having switching mosfets on the output - these are
    different to Lateral mosfets .

    Regards
    Richard Freeman
  32. Archived from groups: rec.audio.pro (More info?)

    "Stephen Sank" <bk11@thuntek.net> wrote in message
    news:cg3r13$6eu$1@reader2.nmix.net...
    > Hey, but at least selenium rectifiers never get dandruff.
    >
    > It is exceedingly rare, in my experience, for any old Hafler amp to fry
    any output devices.
    > About the only way to do it is to bypass the output & supply fuses, turn
    on the amp with the
    > spkr terminals shorted, and crank it up to full power with a 100kHz
    sqarewave for a few hours.
    > Joe Norris used to demonstrate the thermal control on the fan of a DH500
    by shorting both spkr
    > lines & cranking it up to full power for a while, until the fan kicked up
    to high gear.
    > The later Haflers, post DH500/XL600, did use TO-3P package MOSFETs, some
    being the
    > 2SK1058/2SJwhatever lateral types that were supposed to replace the
    2SK134/135/176 &
    > 2SJ49/50/56 laterals, but were discontinued so quickly they're even harder
    to find the the old
    > TO-3 types. The majority of MOSFET's used in current audio are HEXFET
    types.
    >
    Well, that's it. It kept blowing, so I bypased the fuze, but the line
    transfomer itself had a dead short.
    I actually checked that, but the range switch on my meter was defective.
    How's that for bad luck.
  33. Archived from groups: rec.audio.pro (More info?)

    In article <JK2dnfAA1pyooLvcRVn-uQ@giganews.com>, Sugarite <not for you> wrote:
    >
    >Well, that's it. It kept blowing, so I bypased the fuze, but the line
    >transfomer itself had a dead short.
    >I actually checked that, but the range switch on my meter was defective.
    >How's that for bad luck.

    What makes you think that?
    You can't check a transformer with a DC meter.

    A transformer is supposed to reflect the impedance of the secondary,
    through a static ratio. If the transformer secondary has a dead short
    across it, the transformer primary will behave like it has a dead short
    across it.

    Transformers don't fail often. Rectifiers and output stages fail all
    the time.

    Disconnect the transformer secondary and try again. The transformer
    will almost certainly not be the problem.
    --scott

    Oh, yes, and don't bypass fuses, ever, under any circumstances. THAT
    is how transformers get damaged. What did you do with the real Sugarite?
    --
    "C'est un Nagra. C'est suisse, et tres, tres precis."
  34. Archived from groups: rec.audio.pro (More info?)

    "Pooh Bear"
    > Stephen Sank wrote:
    >
    > > Hey, but at least selenium rectifiers never get dandruff.
    > >
    > > It is exceedingly rare, in my experience, for any old Hafler amp to fry
    any output devices.
    > > About the only way to do it is to bypass the output & supply fuses, turn
    on the amp with the
    > > spkr terminals shorted, and crank it up to full power with a 100kHz
    sqarewave for a few hours.
    > > Joe Norris used to demonstrate the thermal control on the fan of a DH500
    by shorting both spkr
    > > lines & cranking it up to full power for a while, until the fan kicked
    up to high gear.
    > > The later Haflers, post DH500/XL600, did use TO-3P package MOSFETs, some
    being the
    > > 2SK1058/2SJwhatever
    >
    > 2SJ192 IIRC


    ** You recall incorrectly.


    >
    > > lateral types that were supposed to replace the 2SK134/135/176 &
    > > 2SJ49/50/56 laterals, but were discontinued so quickly they're even
    harder to find the the old
    > > TO-3 types. The majority of MOSFET's used in current audio are HEXFET
    types.
    >
    > They are ? For linear outputs as opposed to PWM ?


    ** Yes - very common in US made products.

    The IRFP240 and IRFP9240 being a favourite pair.


    ........... Phil
  35. Archived from groups: rec.audio.pro (More info?)

    Phil Allison wrote:

    > "Pooh Bear"
    > > Stephen Sank wrote:
    > >
    > > > The later Haflers, post DH500/XL600, did use TO-3P package MOSFETs, some
    > being the
    > > > 2SK1058/2SJwhatever
    > >
    > > 2SJ192 IIRC
    >
    > ** You recall incorrectly.

    Ah yeah - 2SJ162 - got one number wrong. Been a while since I used them.


    > > > lateral types that were supposed to replace the 2SK134/135/176 &
    > > > 2SJ49/50/56 laterals, but were discontinued so quickly they're even
    > harder to find the the old
    > > > TO-3 types. The majority of MOSFET's used in current audio are HEXFET
    > types.
    > >
    > > They are ? For linear outputs as opposed to PWM ?
    >
    > ** Yes - very common in US made products.
    >
    > The IRFP240 and IRFP9240 being a favourite pair.

    Interesting. How well do they match for bias ? That seems to a classic problem
    with vertical FETs.


    Graham
  36. Archived from groups: rec.audio.pro (More info?)

    "Pooh Bear"
    >
    > Phil Allison wrote:
    >
    > >
    > > ** Yes - very common in US made products.
    > >
    > > The IRFP240 and IRFP9240 being a favourite pair.
    >
    > Interesting. How well do they match for bias ? That seems to a classic
    problem
    > with vertical FETs.
    >


    ** Matched sets *are* required ( plus ballast rsistors) - which makes
    later repairs interesting.


    ............. Phil
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