ÁÄÄÉÎÇ ÁÎ ÅØÔÒÁ ÓÉÄ 6581 ÃÈÉÐ BY: ÍARK Á. ÄICKENSON AND [ÃHARLIE ÙOUNG] ÎOTE FROM ÃHARLIE ÙOUNG: É ADDED A SECOND CHIP TO MY Ã64C FOLLOWING ÍARK'S INSTRUCTIONS AND A Ã64 SCHEMATIC. ÏNE OF THE CHIPS THAT ÍARK REFERRED TO DOES NOT EXIST IN MY COMPUTER. ÔHIS UPDATED SET OF INSTRUCTIONS SHOULD WORK FOR ANY Ã64 OR Ã128 COMPUTER. ÔHIS IS NOT A PROJECT TO BE TACKLED BY THE SQEAMISH OR PEOPLE WHO ARE DEATHLY AFRAID OF OPENING THEIR COMPUTER JUST TO TAKE A PEEK INSIDE. [ÉF YOU WERE ONE OF THEM, YOU WOULD BUY THE STEREO CARTRIDGE FROM ÃÍÄ]. ÈOWEVER, THE INSTRUCTIONS ARE FAIRLY SIMPLE. ÉF YOU MESS SOMETHING UP, IT WILL PROBABLY BE THE SOUND CHIP. ÈOPEFULLY THE REST OF THE COMPUTER WOULD NOT BE AFFECTED. ÎO LIABILITY IS ASSUMED WITH RESPECT TO THE USE OF THE FOLLOWING INFORMATION. ÉN OTHER WORDS IF YOU SCREW-UP TRYING TO INSTALL THIS MODIFICATION, THEN IT'S YOUR RESPONSABILITY. ÙÏÕ ÄÏ ÔÈÉÓ ÁÔ ÙÏÕÒ Ï×Î ÒÉÓË!!!! ÏÖÅÒÖÉÅ× ÙOU WILL PIGGYBACK A SECOND ÓÉÄ CHIP TO THE ORIGINAL. ÁLL DATA, ADDRESS, AND POWER PINS WILL BE SOLDERED TO THE ORIGINAL CHIP. ÓEVERAL OTHER PINS WILL NOT BE SOLDERED TO THE ORIGINAL, SO PAY ATTENTION TO THE INSTRUCTIONS. ÙOU WILL BUILD A SIMPLE AUDIO AMPLIFIER ON A SMALL PIECE OF PERF BOARD. ÐLEASE READ THROUGH THE INSTRUCTION BEFORE STARTING CONSTRUCTION. ÐÁÒÔÓ 1 - 6581 ÓÉÄ CHIP 1 - 2Î2222 TRANSISTOR 2 - 470PF [2,200PF] CAPACITORS [É USED 2,200PF CAPS BECAUSE THAT WAS THE VALUE IN MY Ã64 SCHEMATIC] 2 - 1K OHM 1/4 WATT RESISTORS 1 - .001 UF CAPACITOR 1 - 10K OHM 1/4 WATT RESISTOR 1 - 10 UF ELECTROLITIC CAPACITOR 1 - SMALL ÄÐÓÔ SWITCH - INSULATED HOOKUP WIRE - SHIELDED AUDIO CABLE - SILICON HEAT SINK GREASE 2 - CHASIS MOUNT FEMALE ÒÃÁ PLUG (LIKE YOU NORMALLY FIND ON THE BACK OF YOUR STEREO). ÈÏ× ÔÏ ÄÏ ÉÔ ÐRINT THESE INSTRUCTIONS, AND CHECK OFF EACH STEP AS YOU DO IT. ÄISCONNECT THE POWER SUPPLY. ÔAKE THE COMPUTER CASE APART. ÒEMOVE THE KEYBOARD. ÔAKE OFF THE TOP SHIELD. ÙOU DO NOT HAVE TO REMOVE THE MAIN BOARD. ÉF YOU CONNECT THE POWER SUPPLY TO CHECK VOLTAGES, DISCONNECT IT BEFORE DOING ANY SOLDERING. ÙOU SHOULD GROUND YOURSELF WITH A STATIC GUARD WRISTBAND (SUCH AS WHAT ÒADIO ÓHACK SELLS). ÅVEN THOUGH THE CHIP IS QUITE DURABLE, JUST THE RIGHT STATIC DISCHARGE CAN RUIN ALL OR PART OF THE ÓÉÄ CHIP. ÐAGE 1 ÁDD 2ND ÓÉÄ ÎOTE WHICH WAY THE ORIGINAL ÓÉÄ CHIP IS INSTALLED. ÔHE NOTCH PROBABLY FACES THE BACK OF THE COMPUTER. ÒEMOVE THE ORIGINAL CHIP. ÐULL IT STRAIGHT UP USING A CHIP PULLER OR PRY WITH A SMALL SCREWDRIVER AT BOTH ENDS. ÐUT THE SECOND CHIP IN THE SOCKET AND TRY IT OUT. ÙOU WILL HAVE TO REINSTALL THE KEYBOARD TO DO THIS, BUT YOU DO NOT HAVE TO PUT THE CASE BACK TOGETHER. ÉF YOU BOUGHT THE CHIP FROM ÇRAPEVINE, IT MAY BE BAD -- ESPECIALLY IF IT HAS PINS MISSING. ÉF THE SECOND CHIP IS GOOD, THEN YOU ARE READY TO BEGIN PIGGYBACKING. ÈERE IS A SHORT EXPLANATION OF THE WAY PINS ARE NUMBERED ON AN Éà CHIP. ÏN ONE END OF THE Éà YOU SHOULD FIND A LITTLE NOTCH. ÌOOKING AT THE CHIP WITH THE NOTCH AT THE TOP THE NUMBERING GOES THIS WAY. ÔHE UPPER LEFT CORNER OF THE CHIP IS PIN 1 AND THEY ARE NUMBERED CONSECUTIVELY, COUNTER-CLOCKWISE AROUND THE CHIP. ÓOME CHIPS DO NOT HAVE A NOTCH IN ONE END, BUT INSTEAD A DOT IS PLACED IN ONE OF THE CHIP CORNERS TO DESIGNATE THAT PIN 1 STARTS IN THAT LOCATION. NOTCH ----,,---- 1-!. !-8 2-! DOT !-7 3-! !-6 4-! !-5 ---------- ÆIRST BEND OUT PINS 23, 24 AND 26 AND CUT THEM OFF OF THE 6581 ÓÉÄ CHIP. ÔHESE ARE FOR THE TWO ANALOG (PADDLES) AND ONE AUDIO INPUT LINES. ÔHEY WILL CAUSE PROBLEMS IF CONNECTED AND SINCE THEY WILL NOT BE USED IT IS BEST TO REMOVE THEM. ÎOW BEND OUT PINS 1, 2, 3, 4, 8, 27. ÃHARLIE RECOMMENDS MAKING A HEAT SINK. ÆIND A THIN NARROW STRIP OF METAL THAT IS LONGER AND NARROWER THAN THE ÓÉÄ CHIP. ÃOVER THE TOP OF THE ORIGINAL CHIP WITH A THIN LAYER OF HEAT SINK GREASE. ÌAY THE STRIP ON TOP OF THE ORIGINAL CHIP. ÙOU MIGHT FASTEN IT WITH A SMALL SPOT OF GLUE TO MAKE SURE THAT IT DOES NOT MOVE AND SHORT THE PINS LATER. ÎOW SMEAR THE BOTTOM OF THE SECOND CHIP WITH A THIN LAYER OF HEAT SINK GREASE. ÍAKE SURE THE NOTCHES FACE THE SAME WAY, AND MAKE THE SANDWICH. ÂEND THE HEAT SINK STRIP OVER THE END AND TOP OF THE TOP CHIP. ÙOU WILL WANT THIS STRIP TO TOUCH THE TOP SHIELD WHEN YOU REPLACE IT. ÐREPARE TO SOLDER. ÙOU WILL BE SOLDERING SOME PINS OF THE TOP CHIP TO THE BOTTOM CHIP. ÓOLDER ONE OF THE 2,200PF CAPACITORS TO PINS 1 AND 2 THEN SOLDER THE OTHER 2,200PF CAPACITOR TO PINS 3 AND 4. ÔHE CAPACITORS CONTROL THE UPPER AND LOWER FREQUENCY RANGE OF THE ÓÉÄ CHIP. ÎOW SOLDER THE REMAINING PINS (EXCLUDING THE ONES WE HAVE BENT OUT AND ALSO REMOVED 1, 2, 3, 4, 8, 23, 24, 26 AND 27) TO THE ORIGINAL ÓÉÄ CHIP. ÙOU MAY HAVE TO BEND THE TOP CHIP PINS INWARD JUST A LITTLE FOR THEM TO GET A GOOD GRIP ON THE BOTTOM CHIP. ÂE VERY CAREFUL NOT LEAVE THE SOLDERING IRON ON THE CHIP ÔÏÏ LONG AS YOU COULD RUIN ÂÏÔÈ ÓÉÄ CHIPS. ÎOW THAT YOU HAVE THE CHIPS SOLDERED TOGETHER PLACE THE ÓÉÄ CHIPS BACK IN THE SOCKET. ÐAGE 2 ÁDD 2ND ÓÉÄ ÄÅÓÅÌÅÃÔ Ó×ÉÔÃÈ ÙOUR SECOND ÓÉÄ CHIP WILL WORK WITHOUT THIS SWITCH, BUT SOME OF YOUR CARTRIDGES MAY NOT. ÙOU CAN SKIP THIS SECTION AND INSTALL THE SWITCH LATER IF NEEDED. ×ITH THE SWITCH OFF, THE SECOND CHIP IS INVISIBLE TO THE COMPUTER -- THE CHIP SELECT PIN STAYS HIGH ALL THE TIME WHICH KEEPS THE CHIP FROM RESPONDING TO ANY READS OR WRITES. ÉF YOU TURN THE SWITCH OFF WHILE CHIP 2 IS GENERATING SOUND, THE SOUND WILL CONTINUE, BUT THE CHIP WILL NOT RESPOND TO ANY FURTHER INSTRUCTIONS UNTIL YOU TURN THE SWITCH BACK ON. ÄRILL A HOLE AND MOUNT THE ÄÐÓÔ SWITCH IN THE COMPUTER. É USED THE SPACE BETWEEN THE ÒÆ MODULATOR AND THE VIDEO/AUDIO ÄÉÎ CONNECTOR. ÁN ORIGINAL Ã64 HAS MORE ROOM ABOVE THE ÒÆ CONNECTOR, SO THAT MAY BE A GOOD PLACE. 5Ö ÓOLDER A PIECE OF WIRE TO PIN 2 OF THE CASSETTE CONNECTOR. ÌOOKING AT THE BACK OF THE COMPUTER THAT IS THE SECOND PIN FROM THE LEFT. ÙOU COULD MAKE SURE YOU HAVE THE RIGHT PIN BY POWERING THE COMPUTER ON AND CHECKING THAT PIN WITH A METER. ÓOLDER THE OTHER END TO THE TOP TERMINAL OF THE SWITCH. ÃHIP ÓELECT ÓOLDER A PIECE OF WIRE TO PIN 10 OF THE CARTRIDGE CONNECTOR. ×ITH THE COMPUTER FACING YOU, THE CONNECTOR IS AT THE BACK RIGHT. ÐIN 10 IS THE 10TH PIN FROM THE LEFT. ÙOU CAN WRAP THE WIRE AROUND THE PIN THAT ANGLES FROM THE TOP OF THE CONNECTOR TO THE BOARD. ÍAKE SURE THE WIRE DOES NOT SHORT TO PIN 9 OR 11. ÓOLDER THE OTHER END OF THE WIRE TO THE BOTTOM TERMINAL OF THE SWITCH. ÓOLDER A WIRE TO PIN 8 OF THE SECOND ÓÉÄ CHIP. ÓOLDER THE OTHER END TO THE MIDDLE TERMINAL OF THE SWITCH. ÁLTERNATIVE ÓÐÓÔ ÙOU COULD PROBABLY USE A ÓÐÓÔ SWITCH AND A PULLUP RESISTOR. ÁLTERNATIVE ADDRESS ÙOU COULD USE PIN 7 ON THE CARTRIDGE CONNECTOR FOR ADDRESS $ÄÅ00. ÙOU COULD ACTUALLY HAVE A TOTAL OF 3 ÓÉÄ CHIPS. ÃHIP 2 - $ÄÆ00 ÃHIP 3 - $ÄÅ00 ÄON'T KNOW OF ANY PLAYER THAT ADDRESSES 3 CHIPS THOUGH. ÁÕÄÉÏ ÁÍÐ ÍOUNT THE TWO ÒÃÁ CONNECTORS ON THE BACK OF THE COMPUTER. ÈERE IS A SCHEMATIC OF THE AUDIO OUTPUT CIRCUIT. ÃONSTRUCT THIS ON A PIECE OF PERF BOARD. É PUT THIS AUDIO CIRCUIT UNDER THE KEYBOARD. ÐAGE 3 ÁDD 2ND ÓÉÄ ÐIN 27 ON 12VOLTS DC ÓÉÄ CHIP RESISTOR ! --. 10K OHM !COLLECTOR 27!----.--/!/!/--.-----Ï 2N2222 --' ! ! !EMITTER ! ! ! 1K ! ! + 1K !