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NES Control Pad Conversion FAQ

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HOW TO CONVERT AN 8-BIT NES CONTROL PAD TO ATARI 2600/7800 (2-BUTTON).
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AUTHOR: Graham.J.Percy  
EMAIL:  gjp57@yahoo.com
PHONE:  (61) 03 5978 7198

FAQ Version 1.0a, 18th September, 1998.

Copyright (c) 1998 Graham.J.Percy

All rights reserved. This document may be reproduced, in whole or in part,
provided the copyright notice remains intact and no fee is charged.
The data contained herein is provided for informational purposes only.
No warranty is made with regards to the accuracy of the information.

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1/  Find a good Atari 2600/7800 two-button joypad. (Check that all functions
    are working. ie 4 directions and 2 buttons). Remove the back of the 
    joypad and desolder the joypad lead from the Printed Circuit Board (PCB).
    (You will need the lead later).

2/  Find a good 8-bit NES control pad (eg. Model NES-004E) and remove the 
    back. Check that rubber mounted electrical contacts are in good cond-
    ition. Clean if necessary.

    De-solder the NES lead, the two discreet resistors (R1 & R2, see below),
    and the 16-pin chip and discard. It's important not to damage the chip
    connection points on the PCB. To this end I find it helps to carefully
    file through the legs of the chip to remove the chip body, then the chip
    pins can be desoldered from the PCB individually.
                       

  POINT "CE"__         ______________________________________________
              |       | o  R1  o                       oU            |
              V       | o  R2  o                         oV          |
         _____________|           ABCDEFGH                 oW     o o|
       /  ---- ----     X X X X   oooooooo      R  S         oX      |
     /        0         X X X X   --------  Q X X  X X               |
    |                   X X X X  |  chip  |   X X  X X       oY      |
    |                             --------    X X  X X               |
    |     0   0   0               oooooooo           T               |
    |                             IJKLMNOP                           |
    |                                                                |
    |         0                                                      |
    |________________________________________________________________|


3/   Use a razor blade or small drill to cut the circuit on the PCB
     adjacent to the board edge at point CE (common earth). This seperates 
     the button-common circuit (ORG) from the earth circuit (BLK).

4/   There are 8 vertical black strips on the PCB which are high value
     printed resistors. They must all be disconnected from the circuit or
     otherwise removed (eg. by scraping off). To this end:-

     - Use a razor blade or small drill to cut the circuit on the board 
       directly ABOVE holes J, K, L & M.
     
     - Do the same at the very end of each of the black strips on the right
       (at points Q, R, S & T).

     If you have a multimeter then check that hole H is not connected to
     any of the other chip holes (A thru G and I thru P). If this checks
     out then you are ready to begin rewiring.

5A/  The following connections will allow buttons B & A to be used as
     Atari buttons #1 & #2 respectively. If you wish to connect and use 
     all 4 NES buttons then go to STEP 5B.  

     Using insulated solid core hook-up wire (eg. bell-wire 1 X 0.6mm)
     and by passing wires through the back of the PCB, connect the 
     following hole pairs:-

                         B  TO  P
                         H  TO  I
                         A  TO  G

     Goto STEP 6.

5B/  Using insulated solid core hook-up wire (eg. bell-wire 1 X 0.6mm)
     and by passing wires through the back of the PCB, connect the 
     following hole pairs:-

                         B  TO  N
                         E  TO  P
                         H  TO  I
                         A  TO  F

     Using a small dolop of solder bridge across the following holes:-

                         F  TO  G
                    &    N  TO  O  TO  P

6/   Solder two 1/4w, 620 OHM resistors in place of R1 and R2. (Resistors 
     from the Atari joypad may be used).

7/   Pass Atari joypad lead wires through the back of the NES PCB and solder
     in place as indicated:-

                    WIRE COLOUR        HOLE (SEE ABOVE DIAGRAM)

                    brown               J
                    green               K
                    blue                L
                    white               M

                    black               U
                    yellow              V
                    red                 W
                    orange              X

8/   Reassemble the NES pad case. You now have a 2-button NES control pad
     which is electrically the same as the 2-button Atari joypad!
     The NES controller makes an excellent pad for the Atari
     2600 & 7800 with fine sensitivity. HAVE FUN!

        NES BUTTON             "SELECT"  "START"    "B"      "A"
     
        ATARI 7800 BUTTON         #1       #2       #1       #2


I would appreciate any comments you may have on this modification, 
particularly if you try it yourself.  Good gaming!  GP
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AtariAge - NES Control Pad Conversion FAQ