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From: rubywand@swbell.net
Newsgroups: comp.sys.apple2
Subject: Re: Return fixing & Color killing?
Date: Tue, 18 Mar 1997 06:03:20 +0000
Organization: Southwestern Bell Internet Services
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Edhel Iaur, Esq. wrote:
> 
> On Tue, 04 Mar 1997 06:07:49 +0000, rubywand@swbell.net wrote:
> 
> >Edhel Iaur, Esq. wrote:
> 
> >> Does anybody remember the book _Enhancing Your Apple II_?  Well, I
> >> just bought a pack of resistors, and opened up my //e to do the "Color
> >> Killer Mod".  However, as the title implies, the book is apparently
> >> written for Apple // users, not Apple //e users.  The chips, etc. are
> >> in a totally different position.  Does anybody know how to do the
> >> "Color Killer Mod" on a //e?
> 
> > .... I don't know about the color-killer mod you
> >mention. What is it supposed to do?
> 
> FINALLY!  I Just got this article!  It's supposed to turn everything
> monochromatic (like that button on the good Apple color monitors), via
> sovtware, via one of the announciators.

     Thanks for the info. It looks like you should be able to do this kind 
of full-screen color-killer on a IIe by using a general purpose NPN 
transistor (2N3904, 2N2222, etc.) to shunt the Color Burst signal. The 
transistor's collector would connect to the junction of R15 and R13; the 
emitter lead would go to Ground. The transistor should be connected directly 
to the R15-R13 junction and ground. 

     The base lead would go through a 2k-3k Ohm resistor to an annunciator 
output, such as An-3 at pin 12 on the 16-pin J-15 Game connector. PEEKing 
the appropriate addresses should flip Color OFF and ON.

     The reason for qualifiers such as "looks like", etc. is that I have not 
actually tried a mod like this on a IIe. Monitors are remarkably sensitive 
to Color Burst. If the transistor does not do a good job of shunting the 
signal, enough may get through to trigger Color-ON.


     A more positve (but less easy) technique is to use a 74LS32 OR gate to 
control flow of the 3.58MHz signal. The IC could be tack-soldered onto U88 
via its +5 and GND pins. U88 is the 74S02 which has the gate which produces 
Color Burst.

     Pin 12 of the 'S02 would be bent up and connected to the output of an 
'LS32 OR gate (e.g. pin 3). One of the OR gate's inputs (pin 2) would go to 
Pin 12 of the 'S02 socket. The other (pin 1) would go to an annunciator 
output.

     Turning ON the annunciator forces the OR gate output to "1" and 
eliminates Color Burst. Turning OFF the annunciator lets the OR gate output 
follow the 3.58MHz signal and enables Color Burst.  


Rubywand