From: skelly@amiganet.chi.il.us (Sean Kelly)
Newsgroups: rec.games.video
Subject: ColecoVision Hack....
Date: 15 Nov 92 10:41:16 GMT
Organization: Amiga Network Information Systems


 
 
     Well, someone asked about this the other day so here it is.  The hack to
the ColecoVision to give separate audio & video outputs.  Please read the text
completely and carefully as I do realize it may sound pretty confusing...

============================================================================== 

ColecoVision A/V Outputs by Sean Kelly                       11-15-92


        This is a rather feeble attempt at describing the hack to the
ColecoVision video game system to give separate audio and video outputs to
the system.  I am what I call an "Electronics Tinkerer" meaning I have no
formal education in electronics and basically only know what I have been
able to figure out by ripping apart everything I own <grin>!  I will try to
"draw" an ASCII schematic for the hack, but I have also never done this
before so bear with me.

        I am a collector of Classic video games and systems and ran across
this hack on one of the many ColecoVision systems I own.  It actually works
quite well and gives the on-screen images a much crisper look to them.
Audio is generally pretty poor on the ColecoVision and this hack doesn't do
much to help it.

Let's get down to business now!


        In order to get things started you have to open up the ColecoVision
by removing the 8 screws on the bottom of the case.  With the screws
removed, the case is still something of a pain to open because of the lip on
the expansion port, but just keep working at it and it will eventually come
apart.  Next thing is to remove the screws holding down the motherboard
itself (three of them I believe) and take the motherboard out of the case.
On some versions of the ColecoVision the aluminum cover is soldered to the
circuit board.  If this is the case on yours, you will have to desolder it
and remove both the top and bottom parts to the aluminum cover.  Set
everything but the motherboard aside and you are ready to get to work.

        The person that did the hack on this system uses a small
automotive-type fuse block terminal to mount the components of the circuit
board on.  I have located it in the 1992 Radio Shack catalog (page 150) and
it is RS part #274-688.  It comes in a package of four for $1.29.  Here is a
list of the components used:  AGAIN - I have no formal electronics education
and don't really know how to read all the weird symbols on the parts.  I will
do my best to describe them (I have also labeled them on the line below for
future reference - take note):

  Transistor - No part # markings at all.  Only thing on it is a white, red,
  (T1)         and green stripe in that order from top to bottom.  I assume
               this tells what kind/type it is?
 
               POSSIBLE (!) RS Part #276-1617   $1.98 (pkg. of 2)

  Capacitor  - Electrolytic type with  part #N8408 on it.  It also has the
  (C1)         marking "470uf 35v", but the "u" is one of the funny symbols
               that I have no idea what it means.

               RS Part #272-1030    $ .99

  Capacitor  - Ceramic Disc type.  Only marking on it is an underlined "47".
  (C2)

               RS Part #272-121   $ .39 (pkg. of 2)

  Resistor   - I know these are defined by the colored stripes (See - I'm
  (R1)         not a complete idiot!!  haha).  The stripes are: Orange,
               Orange, Brown, and Gold.

  A/V Cable  - One Audio/Video cable with the RCA plugs cut off on one end.

  You will also need about 5 small pieces of wire around 4" long each.



     We're looking at a total of about five bucks to do this so for parts
that do not come in packages of two or more, I would suggest buying an extra
one, unless you know what you're doing, in case you screw something up.

     The center connector on your terminal will be the ground for all the
components because it is the only terminal that sticks out on both sides of
the block.  The part the extends on the bottom will be used to mount to
terminal to the ColecoVision motherboard.  Directly to the right of the RF
modulator (big silver box on the motherboard) right under the letter of the
revision of the motherboard (the one I am looking at is "J") you will have
to scrape off a section of the green coating so you can solder the terminal
on the botton to the motherboard.  After soldering this bend the terminal
block so that it is standing straight up from the motherboard.

     Since many of the components will be "tied" together, you might wanna
connect them all to the posts first and then solder them later.  The way I
am going to describe how to connect them will (hopefully) make it as easy as
possible to understand.  The following is a listing of each post numbered
from 1-5, left to right, looking at the terminal block from the back of the
motherboard.  Looking at the "back" you will be looking at the channel 3-4
switch as well as the RCA plug that is used to connect the ColecoVision to
the TV/Game switch now.  Here is what goes on each post:
 
  Post #1 - The LEFT "leg" of the transistor.  I am looking at the
            transistor on the side that is curved - where you can see the 
            color bands.

            One of the small pieces of wire goes from this post to the right
            leg of the disc capacitor on the ColecoVision motherboard
            itself marked "C22".


  Post #2 - The CENTER "leg" of the transistor.

            One "leg" from the Disc capacitor.

            One of the small pieces of wire goes from this post to the
            underside of the ColecoVision motherboard.  It will be EXTREMELY
            hard for me to explain where to connect this on the bottom of
            the motherboard since there are no markings on this side.  The
            only way I can describe it is to say that it is being connected
            to one of the components in the RF modulator.  The RF modulator
            is "outlined" in a sense on the bottom of the MB with solder
            because of grounding.  You need to connect it to the pin that
            has the marking "+12" at about 5 O'Clock.  This is the closest
            pin to he "+12" marking.


  Post #3 - This is the GROUND post.  One side of the resistor is connected
            here.

            The two ground wires from the RCA cables must be connected here
            also.  Each Audio/Video wire has two wires inside of it.  In
            general, one is shielded in plastic and the other is not.  The
            unshielded wire is the ground.  Connect the unshielded wire from
            each cable to this post.


  Post #4 - The side of the Electrolytic capacitor (C1) that the arrow
            printed on the capacitor points to.

            This is where I am sort of unable to help you.  The postitive
            wire from the Audio or Video wire needs to be connected to this
            post.  Since the RCA ends are cut off the cable I don't know
            which is which.  It should not damage anything by connecting
            them the wrong way, so you will have to take a guess.  One of
            them goes on this post and the other goes on post #5.

 
  Post #5 - The other of the positive Audio/Video wires gets connected here.
 
            One of the small pieces of wire goes here.  This one is even
            harder to describe than the one on post 2.  The "outline" in
            solder around where the RF modulator is mounted on the opposite
            side is where you are going to connect this wire.  Looking at
            the bottom of the MB with the expansion port facing you the part
            of the "outline" you need to connect this wire to will be on
            your left.  It's  small section of solder (compared to the
            section on the right) and is about 1.5-2 inches long.  Connect
            this wire anyplace here.



  You now have one leg of the transistor (T1), one leg of the resistor (R1),
  and one leg of each capacitor just hanging there right?  Connect all of
  these together, but do not connect them to any of the posts.  Just sort of
  let them hang there.


  The person who did this to my system also has one other wire connected to
  the bottom of the motherboard, but the other end of it has been cut and is
  not connected to anything.  I assume this serves no purpose.



     Well, I DID make an attempt at an ASCII schematic of this thing, but it
was pathetic!  I HOPE the text above will give you a good enough idea how to
do it.  I described it to the best of my ability, but I can certainly see
where and why it might be misunderstood.  I will not be responsible for any
damage you may cause to your system as a direct or indirect result of this
text file.  Use it at your own risk.  I would strongly suggest that it be
used only by people with more than one system for the simple reason that
there is a possibility you could damage your system if misinterpret the
directions above.

     As a side-note to this project, something else I got with this hacked
ColecoVision is an interface to copy ColecoVision cartridges themselves, but
guess what - I have no idea how to use it either.  It came with about 20
Eproms with 2 games each on them and a modified cartridge that I can plug
the chips in.  It plugs into the expansion port of the ColecoVision and has
a standard 25-pin serial cable that I assume is to connect to the RS-232C
port on the Eprom programmer (something else I don't have!).  If anyone has
something like this and knows how to use it PLEASE let me know.  I would
love to be able to get it working!

%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%
%   Sean Kelly - Sysop Amizon BBS (312)594-1146                         %
%   Always looking for classic video games for the following systems:   %
%                                                                       %
%  Atari 2600-Atari 5200-ColecoVision-Atari 5200-Intellivision-Vectrex  %
%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%^%