--------------------------------------------------------------------------- HOW TO CONVERT AN 8-BIT NES CONTROL PAD TO ATARI 2600/7800 (2-BUTTON). ---------------------------------------------------------------------------- AUTHOR: Graham.J.Percy EMAIL: gjp57@yahoo.com PHONE: (61) 03 5978 7198 FAQ Version 1.1, 6th April, 2004. Copyright (c) 1998, 2004 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. ---------------------------------------------------------------------------- 1/ Find a good Atari 2600/7800 two-button joypad or a 7800 Joystick. (Check that all functions are working. ie 4 directions and 2 buttons). Remove the back of the controller, and desolder the 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-004 or NES-004E) and remove the back. Check that rubber mounted electrical contacts are in good condition. Clean if necessary. De-solder the NES lead 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. If you are using a NES-004E pad, then de-solder the two discreet res- istors (R1 & R2, see below). 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/ If you are using a NES-004 pad, then use two 1/4w, 620 Ohm resistors to jumper U to V and U to W. If you are using a NES-004E pad, then solder two 1/4w, 620 Ohm resistors in place of R1 and R2. (Resistors from the Atari joypad or 7800 Joystick may be used). 7/ Pass Atari joypad lead wires through the back of the NES PCB and solder in place as indicated:- PIN WIRE COLOUR (Ref') HOLE (SEE ABOVE DIAGRAM) 4 brown J 3 green K 2 blue L 1 white M 8 black U 9 yellow V 5 red W 6 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 9/ Trouble Shooting the NES Pad Conversion Check for unintentional connections by testing pin-outs at the 9-pin female joystick connector:- - Pins 1,2,3,4,6,7 = each of these should have no connection to any other pin-out - Pin 5 to 8 = 620 Ohm - Pin 5 to 9 = 1240 Ohm - Pin 8 to 9 = 620 Ohm ------------------ \ o5 o4 o3 o2 o1 / \ o9 o8 o7 o6 / \____________/ 10/ Credits - Thanks to B.Cross for alerting me to the differences between the North American NES-004 and the locally available NES-004E. Thanks for all the info and scans! - Thanks to Brad Karston for help in resolving the mod design for the NES-004. I would appreciate any comments you may have on this modification, particularly if you try it yourself. Good gaming! GP --------------------------------------------------------------------------- FILE:- NES-7800.TXT