On Saturday, May 3, 1997 at 12:00:00 AM UTC-7, Zonn Moore wrote:

On Fri, 02 May 1997 09:31:15 GMT, rlb...@cedar-rapids.net (Rodger Boots) wrote:
~ On Thu, 01 May 1997 02:00:51 GMT, zo...@concentric.net (Zonn Moore)
~ wrote:
~
~ >
~ >On 29 Apr 1997 15:01:43 GMT, r...@ihgp3.ih.lucent.com (Rick Schieve) wrote:
~ >
~ >~ In article <5k28gf$h...@drn.zippo.com>, Wade Tsai <ep6...@shellus.com> wrote:
~ >~ >
~ >~ >A week ago I had asked for information about what might be causing
~ >~ >R636 (100 ohm) in my G08 to smoke instantly. It turns out that
~ >~ >the deflection transistors that the Zanen kit supplied (3716's)
~ >~ >were woefully underrated. All four 3716's shorted out the moment
~ >~ >power was applied and took out R636 and a few other components
~ >~ >with them.
~ >~ >
~ >~ >Scounging around the shed, I mananged to dig up four 6259's
~ >~ >(which are the original transistors that's used in the G08-003)
~ >~ >to replace the fried transistors.
~ >~
~ >~ I was thinking the other day about the problem of gettting
~ >~ replacement transistors that would handle the current. If one of
~ >~ the serious double E types out there looked at the circuit I'm sure
~ >~ multiple transistors could be used in parallel to share the load.
~ >~ A few resistors would need to be added to balance the load between
~ >~ the multiple transistors (which is where the EE comes in) but it
~ >~ should be do-able and there is plenty of room on the cabinet for
~ >~ some extra heat sinks.
~ >~
~ >~ Any EEs out there looking for something to play with? ;-)
~ >
~ >About a year ago I answered a post about a universal X/Y monitor. I had
~ >nominated the Sega X/Y. (Ok laugh! It won't be the first time!)
~ >
~ >Really. It's the fastest so it can play all the games, including the Sega games
~ >(of course) and Cosmic Chasm, which requires a fast monitor. It's also the most
~ >sensitive, so playing the Atari game would require only a resistor divider in
~ >front of the monitor as opposed to an amplifier. And last (and maybe least) it
~ >is already compensated for the bowing effects of Yoke/Picture-tube
~ >non-linearities. This means it'll run Star Wars and other ampliphone type games
~ >as is (with the Resistor divider). And with Tempest and other pre-compensated
~ >games, one simply removes a resistor from the game board, which is much easier
~ >to do than to come up with a WG -> Ampliphone adapter type board.
~ >
~ >It's disadvantage, compared with the Ampliphones, is that it has lower
~ >resolution.
~ >
~ >The biggest problem with the Sega is the underated Transistors (The second ~ >biggest is all the proprietary ICs).
~ >
~ >To fix the transistor problem you can do just what Rick suggests. Parellel two
~ >power transistors for each one currently being fan cooled.
~ >
~ >Since I have a dead Sega X/Y in the garage, I'll be trying this trick real ~ >soon...
~ >
~ >The thing to do is to get two of each transistor, connect the bases and
~ >collectors together. Then connect a resistor from each emitter to the place the
~ >old emitter used to go...
~ >
~ > +-------------------+-----------------> to old collector connection
~ > | to old base |
~ > | ^ |
~ > \ c | c /
~ > \| | |/
~ > | b | b |
~ > |-------------|
~ > >| |<
~ > / e| |e \
~ > | |
~ > | |
~ > \ \
~ > / .39 ohm 1W / .39 ohm 1W
~ > \ \
~ > / /
~ > | |
~ > +--------------------+----------------> to old emitter connection
~ >
~ > (Pretty bad drawing huh?)
~ >
~ >
~ >This is only shown for the PNP transistor, do the same for the NPN's.
~
~ Most all of these monitor used ONLY NPN outputs. There was a version
~ that used a complimentary/symetry output stage (PNP and NPN), but I've
~ never heard of anyone ever seeing one of those.
~
And as usual, your right. I was just thinking of the Atari monitors and the PNP
ASCII drawing looked better than the NPN ASCII drawing...
-Zonn

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