MPSU10 & MPSU60 replacements

Thought I would post this here as it might help some of you (me
included). I've got a G08 deflection board that is missing all the
transistors. Not wanting to spend $25 or more for replacements, Rodger
Boots was able to track some down. Note that the following are not
'drop-in' replacements as the pins are BCE, but are better rated
current-wise and should work much better. BTW, I haven't tested these
yet, so YMMV and all that stuff.

Mark, good for the G08 FAQ?

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MPSU10 and MPSU60 replacements that should work IN A G08.
by Rodger Boots

  Need some of the Motorola Uniwatt transistors used on the Electrohome
  G08 monitor? Good luck as they have been out of production for some
  time, and there is no good (read inexpensive) replacement.

  Looking at the G08 schematics I see we don't need a 300-volt part, 150

  is plenty (my replacements are good for 230). We also don't need the
  half amp, but the ones I picked are good for a full amp. The chosen
ones
  have a bit more frequency capability and double the power handling
  capability. The downside is you may need different heat sinks (not
  really a problem) and the leads are in a different order, but my other

  replacements were like that, too. OK, once again I've gone the DigiKey

  route and kept things under $1 ($.72 each in single quantities).

  For the MPSU10 I'm going to suggest a Toshiba 2SC4793 and for the
MPSU60
  I'm going with the Toshiba 2SA1837. DigiKey has oodles of both and,
  like I said before, prices start at $.72 each or $5.40 for a 10-pack.

  The replacement transistor has to be able to handle the voltage and
  current, and it should be fast enough. It has to be able to handle
the
  power (with heat sinking as needed). Without heatsinking, the Uniwatt
  series handles 1 Watt, up to 10 Watts with heatsinking. The Toshiba
  replacements are good for 2 watts/20 watts. The video outputs probably

  didn't have heatsinks, but the output drivers probably do.

  So you say, what does ‘fast enough' mean in this instance? Nasty
  question. As for CRT video drivers, 10 MHz would be plenty. That would

  also seem to be plenty for the amplifier output drivers. But what I
did
  in this case, was look at the data sheets for the MPSU10 and 60.
  Although frequency response depends on current levels and there are
  charts for this, I wimped out and used the fT spec instead. This gives

  45 MHz for the MPSU10 (versus 100 MHz for the 2SC4793) and 60 MHz for
  the MPSU60 (versus 70 MHz for the 2SA1837). Since the Motorola specs
are
  minimums and the Toshiba specs are typical numbers they are really
about
  the same in real life.

  You don't want to go way too slow and sometimes you get nasty problems

  (oscillations) if you go too fast. (Side note: the oscillation
  problems are sometimes "fixed" by putting ferrite beads on the leads.)

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Received on Fri Mar 7 13:09:30 2003