Re: Some G08 FAQ updates . . .

Christopher X. Candreva wrote:

>I've sent Mark Jenison some updates for the G08 FAQ. I've documented all the
>parts that are on the solder-side of the HV board, and suggest adding a
>reminder that the input protection board doesn't have part IDs screened on
>it.
>
>I also discovered that, should you break the emitter pin off one of the
>MPSU60's -- that would be the pin with the red wire soldered directly to it
>-- the metal case tab is the emitter, and you can solder the red wire
>directly there just fine.
>
>

Sorry, the tab is the COLLECTOR (almost always is) and I can prove it!
Datasheet here <http://www1.cedar-rapids.net/00000028/ihs/mpsu60.pdf>.
It's an odd transistor, we're so used to having the collector lead as
the center leg these days.

>For power transistors, my G08 has two 2N6259's and two MJ15022's . The FAQ
>doesn't mention MJ15022s, and the list archives have 2 mentions of them (and
>the MJ15024, an even heavier duty version). Both are basically questions from
>people who tried them and they seemed to work. I guess I would be number
>three. Specs on the MJ look as good or better than the 6259, but perhaps we
>could get a "final ruling" (Rodger ?:-) on the MJ15022/4 being a suitable
>replacement for the discontinued 6259.
>
>

Datasheets for the 2N6259
<http://www1.cedar-rapids.net/00000028/ihs/2n6259.pdf>, MJ15022
<http://www1.cedar-rapids.net/00000028/ihs/MJ15022.pdf>/4
<http://www1.cedar-rapids.net/00000028/ihs/MJ15022.pdf>, and (oh why
not?) the NTE388 <http://www1.cedar-rapids.net/00000028/ihs/nte388.pdf>.

All have the voltage, current, and power handling capabilities if on a
big enough heatsink. The killer is secondary breakdown. The NTE388
doesn't spec that, the 2N6259 is still the best, but the MJ15022 is
close enough to be used. Seems there was another version of the G08
that used the MJ15022 and it's PNP equivalent in a
complimentary/symmetry output stage insead of the all-NPN 2N6259.

The whole key to not blowing the transistors is to keep them out of the
secondary breakdown area. To do that you need the following:

    1) Don't hold the red reset button in for any length of time
    2) Grounds and +5 power to the boards have to be perfect, John has
told of ways to improve those connections
    3) Keep the monitor power supply voltage where it should be. Line
voltage these days is too high and the power transformer doesn't have a
tap for it. 125 volts going into a 110 or 115 tap makes for too much
voltage to the monitor which makes it run way too hot.
    4) Make sure the fan works and consider mounting another one at the
top of the case blowing OUT of the game cabinet.

Having the boards tell the monitor to deflect off the screen and stay
there will blow the transistors.

>Mouser, incidently, doesn't carry the MJ and recommends the NTE388 at $7.50
>each. DigiKey carries the 15022 and 15024 at $3.75 each.
>
>http://www.vectorlist.org/Vectorlist/2002/10/0143.html
>http://www.vectorlist.org/Vectorlist/2002/07/0231.html
>http://www.ampslab.com/PDF/mj15024.pdf
>
>
>
>
>
>==========================================================
>Chris Candreva -- chris@westnet.com -- (914) 967-7816
>WestNet Internet Services of Westchester
>http://www.westnet.com/
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>
>
>

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Received on Sun Feb 22 01:44:08 2004