Tandy PC-6 Service Manual
Contents
1. gt HE r HEL L Normal Shift O O Li DLL s O Pity Tt ACE 2 o a O O A O O H 5 e BE 1 n LOG a SIN 5 2 HYP SEI 5 ERR HEX Co LLLI 5 X FRAC b TAN ATN OU RESET 00 00 INS DEL LENDS o di 5 12 Km11 Km10 Km9 Km8 Km7 Km6 Km5 Km4 Km3 Km2 Km1 Normal Shift paeoqhay UNJDEGRADGRA R15 ISlin BUZZER EXT 5 CEE CEEP CEE CEED EEE LEE OGRA sg CEER EFEER EEEEREFEFR EEEE 111 EEEF EEEH EEEN PARE EEEH EEFE EEEF icem Aejdsig RADIO SHACK DIVISION TANDY CORPORATION 5 5 76102 CANADA BARRIE ONTARIO L4M 4W5 TANDY CORPORATION AUSTRALIA BELGIUM FRANCE U K 91 KURRAJONG AVENUE RUE DES PIEDS D ALOUETTE 39 147 95022 BILSTON ROAD WEDNESBURY MOUNT DRUITT N 5 W 2710 5140 NANINNECNAMUR CERGY PONTOISE CEDEX WEST MIDLANDS WS 107 JN PRINTED IN JAPAN Q2. Service Mianua POCKET SCIENTIFIC COMPUTER PC 6 Catalog Number 26 3672 5 SPECIFICATIONS ma akui SUN OD 3 How Open Upper Case 3 THEORY OF OPERATION eo eee a ona eld ei OE cite aa sa 4 Block Diagram 542 neon CURE ATE qe a 4 sius ada WC a Po qned W 5 Ram Map a ee ER Ru rea ee n Pa ACRI T c Nati tae 5 Buzzer Control Circuit uoa Fes CREME Ed RR ER eaa A 6 Interrupt Circuit v E E a a GE VICE 6 Keyboard lay a AS eer Boe Y RON Fee 6 Power Supply lt Rea ERE OR o esce P EAR P Vos 7 ESI Pin Functions a l z Pes Santee eet CDL A CRUCE Sa 8 DISPLAY aaa ERO rules at 9 TROUBLESHOOTING GUIDE cd a kt 10 Test Programs uu lblin ci ZQ a DE NON este Pied Risk 11 Operation Check 222 va Q e eee eR AUR dide NIE D Breed 14 PCB ASSEMBLY VIEWS wo Gy d ec 19 PARTS CIST WA a 20 Elec
3. ASSEMBLY VIEW TOP VIEW TOP VIEW 19 5 LIST Electrical Parts CAPACITORS C5 C10 C11 C12 C13 Chip Ceramic 100pF 25V 5 CM21CH101J25V Chip Ceramic O 1uF 15V 100 CM21YV104P15V Electrolytic 22uF 10V 20 CE04C 1A220MS7 Electrolytic 100uF 10V 22095 CE04C 1A101MS ACF 1466 ACF 7347 CE 226MCBA CE 107MCBA ICs 28907311 71032167 28047223 28041047 2 5 LSI CPU HD61747B20 LSI CPU HD61747B25 LSI RAM HM6264ALFP 50 151 MB64H193 IC 4071 PRINTED CIRCUIT BOARD ASSEMBLIES MX 7273 MX 7274 MX 7275 MX 7276 MX 4245 20018364 20018801 20011149 20030453 21004359 Assembly PCB G707 1 Assembly PCB G707 2 RESISTORS 82636701 82636702 R1 R9 R10 R11 R12 R13 R16 R17 R21 R22 R23 R24 Chip Ruthenium 3 3 Kohm 1 8W x 596 CR32 108 332J T TP Chip Ruthenium 12 Kohm 1 8W 596 CR32 108 123J T TP Chip Ruthenium 68 Kohm 1 8W 2 CR32 108 683G T TP Chip Ruthenium 220 ohm 1 8W 10 CR32 108 221K T TP Chip Ruthenium 3 9 Kohm 1 8W 596 CR32 108 392J T TP Chip Ruthenium 10 Kohm 1 8W 2 CR32 108 103G T TP Chip Ruthenium 22 Kohm 1 8W 5 CR32 108 223J T TP Chip Ruthenium 2 2 Mohm 1 8W 5 CR32 108 225J T TP ND 0230EBN ND 0288EBN ND 0354CBN ND 0149FBN ND 0237EBN ND 0281CBN ND 0311EBN ND 0454EBN Chip Rutheniu
4. 061747 10 Replace the 1 51 Test Program Notes 1 After typing in the programs below save the programs to a cassette tape for future use 2 Memory and printer check programs cannot be executed at the same time because of a limited memory capacity Memory check program Ready LIST CLEAR C 904 DEFM C FOR 1 TO C D B B NEXT B ABCDEFGHIJKL MNOPQRSTUVWXYZ BEEP 1 BEEP 1 PRINT INPUT OK ku GOTO 1 Ready LIST 5 7 19 20 30 40 50 60 100 101 110 111 1 1 D B B 100 IF ABCDEFGHI JKLMNOPQRSTUVWX YZ THEN 100 IF A 5 THEN 110 PRINT A GOTO 7 PRINT CHECK N G BEEP 1 BEEP 0 GOTO 111 PRINT Az A PRINT CHECK O K BEEP 1 BEEP 1 PRINT END eas Printer check program Ready P1 LIST 10 MODE 7 20 PRINT pC 6 CHECK 30 PRINT ABCDEFGH IJKLMNOPORSTUVW XYZ 40 PRINT abcdefgh ijklmnopqrstuvw xyz 50 PRINT 0 123456 789 60 PRINT 3 amp lt gt 9986 9 i uy 70 PRINT 1 521 lt lt gt gt amp 80 1 28 90 PRINT 8 100 NEXT A 110 PRINT END 120 8 Program LOAD and MEMORY System 26 3651 PCO m or PC 5 g CMT cable 26 3671 Operation 1 PW SW ON 2 CMT PLAY MODE 3 LOAD BUZZER RUN DEG END Rea
5. non repairable Tape Lead C4957 1 Seal Blind for PCB holder C4991 1 Spacer for lead tape 41003 1 Tape Adhesive for volume shield plate A45344 14 Plate Reinforcement for PCB holder PCB G707 2 Plate Reinforcement for PCB holder PCB G707 1 Tape Adhesive for PCB G707 1 reinforcement Tape Adhesive for PCB G707 2 reinforcement Seal Insulation for volume shield plate C4639 1 Spring Ground for keyboard case A47157 7 Spring Ground for keyboard film C4988 1 Spring Ground for PCB holder C4737 1 Screw Tapping flat head 2 mm x 3 5 mm A45491 13 for PCB holder Screw Tapping flat head 2 mm x 3 mm A45491 11 for connector shield plate Screw Tapping flat head 2 mm x 5 mm 44793 13 for battery CR 1220 Screw Machine pan head 1 7 mm x 5 mm 45919 7 for battery CR 2032 Case Upper for keyboard unit Tandy Case Lower for keyboard unit Tandy Hardware Kit Screw Machine pan head 1 7 mm x 5 4 mm x 3 pieces A45919 8 Battery Lighium CR2032 Battery Lighium for Memory back up CR1220 22 RS Part No AB 0623 AB 0621 AB 0622 AHC 0354 B 0058 ARB 7639 ARB 7640 ARB 7641 2114 0624 ART 0279 AHC 0112 ART 0280 AHC 0355 AHC 0354 ARB 5025 ARB 5045 ARB 5046 AHD 2723 AHD 3002 AHD 3003 AHD 2012 AZ 0110 AHW 2603672 AHD 2013 ACS 0031 ACS 0030 Mfr s Part No 63349650 63349890 63349900 63349910 634
6. electrode of the LCD common signals RO R6 and R8 R14 RO applied horizontally while other signals al ve1 to 12 212 are applied RI vertically on the lower electrodes as shown in above figures R2 In the left figure the upper right corner of the dot is displayed when a vol tage difference exists between signals RO and a1 The CPU outputs the dis play signals to the LCD display CPU HD61747B20 controls the 1st to 6th and 13th to 18th digits of dis play while HD61747B25 controls the 7th to 12th and 19th to 24th digits Symptom TROUBLESHOOTING GUIDE Cause Solution No display at all Weak batteris Replace the batteries Poor battery contact Clean the battery and contact spring Lift the battery spring Peeled heat seal Replace the heat seal Broken heat seal Replace the heat seal LCD CA51 TS Replace the LCD LSI HD61747B Replace the LSI A certain segment s cannot be displayed Peeled heat seal Replace the heat seal Broken heat seal Replace the heat seal LCD 1 5 Replace the LCD LSI HD61747B Replace the LSI Calculation impossible LSI HD61747B Replace the LSI A certain button does not function Poor key contact Celan the contact pad on the PCB and the key contact rubber Broken PC line Connect the PC line Peeled heat seal Replace the heat seal LSI
7. 0 v Km10 Km11 Km12 Keyboard VSS1 VRAM V1 V5 VDD1 VDD2 Power supply voltage for TC4071BF Memory used to keep the voltage for the RAM LCD drive voltages Voltage is generated by connecting the external resistor to VDD2 Power supply for the CPU RAM and options Stays VDD1 at power on Goes to GND at power off or APO auto power off LSI Pin Functions HD61747B20 1C2 HD61747B25 Signal Name In Out Function T In Out Data in out D1 02 D3 D4 In Interrupt signal from RAM In Out Key signal for keyboard In Out Switch signal GND at switch OFF and VDD1 at switch ON 20 24 1 Out Display voltage Divided vol tage from VDD1 25 26 PG2 PG1 Out In CPU internal clock 27 72 R15 R7 Out Display signal 73 GND In GND 74 CE2 In Out Chip designating signal Select RAM or other devices 75 CE1 In Out Select RAM or other devices 76 VDD1 In Power source 77 VDD2 Out VDD1 output from the LSI VDD1 at switch ON and GND switch OFF 61 02 In Out Clock pulse OP In Out Operation signal 4 MB64H 193 Signal Name In Out Function 100 106 In Out Data in out AD0 Out Address signal 107 In Out Data in out AD1 Address signal VSS Power source 02 10 3 Address signal OE Output enable AD4VAD12 In Out Address signal VDD In GND RW Out Read write signal CS6 CS3 Out Chip enable signal CS
8. 1 and 50 minutes of con dition 2 Approximately 2 years with main batteries installed Approximately 6 minutes 32 F to 104 0 C to 40 C 3 4 H x 5 b 8 W x 2 3 4 D 18 mm x 142 mm x 71 mm 5 8 oz 165 g including batteries How To Open Upper Case Tweezers 1 Insert the tweezers into the back of the upper case c 2 Move tweezers gently in the direction indicated by the arrow in the figure below THEORY OPERATION Block Diagram DOT MATRIX DISPLAY 5 x 7 dots 24 digits 7 12 d7 vd12 57712 e7 ve12 c7 vc12 ROWR14 KEYBOARD 1 d1 vd6 b1 ub6 1 c1 vc6 RO vR14 1 12 Ks2 Ks10 KEYBOARD RAM HM6264ALFP ADO AD12 CS3 CS6 100 107 OPTIONS 26 3671 26 3671 26 3652 NOTE Only one of 2 options can be connected at a time LSI Main CPU HD61747B20 Sub CPU HD61747B25 Gate Array MB64H193 RAM HM6264ALFP 50 Ram Map BASIC control Key signal input output lower keyboard 1st to 6th digits and 13th to 18th digits display control Calculation I O control key signal input output upper keyboard 7th to 12th digits and 19th to 24th digits display control Interface between CPU and RAM buzzer control Stores data and program RAM has 8K bytes 64K bits capacity and contains a self control circuit LS ROM CPU Main HD61747B20 113024 bits 1896 bits CPU Su
9. 2 CS0 NC B1 B2 Buzzer signal 52 GND vss VSS 51 GND E NC D4vD1 Data in out OP Operation signal C2 C1 Clock pulse VDD2 Power source CE Chip enable VDD GND 103 405 Data in out IC3 HM6264ALFB 50 Signal Name In Out Function DISPLAY Numbers and characters are displayed in 5 x 7 dots Following is an explanation of a dot matrix LCD e12 c12 a12 d a 0000000 0000000 0000000 Da 11 0000000 0000000 2 N 5 no00000 0000000 Ded Lower electrode Upper electrode Left half 12 digits 000000 2 9n00000 D000000 2 0000000 0000000 0000000 so 0000000 0000000 0000000 0000000 0000000 Q000000 aonoona 0000000 0000000 0000000 0000000 NC A12 A0 In 1 01 1 03 In Out GND In 1 04 4 08 In Out CE1 In A10 In Out OE Out A11 9 8 In Out CE2 In R W VDD Lower electrode Upper electrode Right half 12 digits NC Address signal Data signal VSS terminal Data signal Chip enable Address signal Output enable Address signal GND Read write signal GND el cl al dodad 00000 00000 oooga 00000 apogo dl bl 0 OOGOC R2 00000 R3 00000 A4 O0000 RS 6 the upper
10. 70550 63349640 63297621 63297630 63297640 63297660 63349720 63415940 63416410 52100356 63459150 63470840 63449540 63393830 63500830 63500840 63497930 63500850 63417130 63416020 63470830 63424160 63330000 63319760 63292930 63391680 63470445 82636723 82636709 63426830 CR2032 CR1220 EXPLODED VIEW DISASSEMBLY INSTRUCTIONS 1 Remove 3 screws trom the lower case 3 Remove 9 screws O 1 screw Dana 1 screw 2 Liftup the lower case 8 ana 7 from the PCB holder D and 5 4 Remove the holder and 2 batteries 23 Main Block 8555 gt gt 5 10 MB64H193 SCHEMATIC DIAGRAM 2 61747 25 R17 R21 10 x5 HD61747B20 c1 100pF 2 3 il L 1 Soldering Pads Short Notes Open Short Open Short Open l zl 1C5 4071 R13 R16 3 9 Ko 4 1 resistance values are indicated 2 K 10 M 10 0 2 capacitance values are indicated in u F P 10 pF CR1220 R22 2 C12 22K0 151588 gt R 8 gt s STe e o 2 8 gt lt x gt ci R12 22uF 10V 2209 Ga 001 1 4 12 connector 2202 10V
11. 9 3 BAK EH cos 1 2 ISTAT BRK BUZZER EXTRUN DEG 1910 877 BUZZER EXTRUN DEG Check that the cursor moves E t 71 EC 245 BUZZER ExTRUN UR DEG 1910 877 t 2 1 310 BUZZER EXTRUN DEG STAT 1 2 0 BUZZER EXTRUN 90 BUZZER 90 E 00 BUZZER RUN rays 456 BUZZER RUN B BUZZER RUN BUZZER A 56088 BUZZER A B C BUZ ER Ready Ready P BUZZER Ready P TRACEON BUZZER Ready BUZZER Ready 16 MODE 7 BUZZER RUN GRA PRT ON MODE 8 BUZZER GRA MEMON 1 MODE 9 T BUZZER GRA 1 4 4 EDIT IN BUZZER MEMO 1 Q W R m _ 1 BUZZER GRA 1 BUZZER ASMBL Asmbl Source 1 RUN BRK BUZZER GRA Ready _17 Operation MODE 1 10 BEEP 1 20 S D 10 EXE POWERSW OFF ON Repeat 3 times Turn the contrast volume Read Out BUZZER RUN GRA Ready P 0 BUZZER WRT GRA 10 BEEP 1 BUZZER WRT GRA 20 GOTO 10 BUZzER RUN GRA buzzer sound BUZZER RUN GRA Display must disappear Display should be Ready P The display contrast must change 18
12. b HD61747B25 113024 bits 1896 bits RAM HM6264ALFP 50 65536 bits Input Buffer Code Buffer me wr sr em er m m oem pow _ DATA P DATA GOSUB STACK DISP Buffer 226056 bits 69328 bits Address Users Area Communication Buffer Control Circuit There 3 ways the buzzer 0 1 Mode BEEP 0 BEEP 1 Key Input 82 _ Frequency 0 9 kHz 4 55kHz 4 55kHz B1 Time 110 msec 110 msec 11 msec MB64H193 B B Interrupt Circuit Interrupt circuit for the clock pulse when VDD2 drops 1 When the power is on VDD2 is L level 2 PG2 through the IC and 26th pin of the CPU receive PG2 3 When VDD2 drops the output of the IC becomes GND level and the CPU does not receive PG2 PG1 PG2 HD61747B25 VDD2 Interrupt circuit for the voltage of the Gate Array and options when VDD2 and SW drop 1 When the power is on VDD2 and SW is L level 2 VDD2 for Gate Array and VDD4 is also L level 3 When VDD2 drops VDD2 for Gate Array and VDD4 becomes GND level and stops the op ration of the RAM and options SW VDD2 from IC 4 Sis VDD4 VDD2 from IC 2 Keyboard HD61747B25 controls the upper keyboard Ks3 Ks8 Upper De174782d 98 i o HD61747B20 controls the lower keyboard Km1 Km4 Lower HD61747B2
13. dy 4 PW SW OFF Take out the 26 3651 CMT 5 PW SW ON BUZZER RUN DEG Ready 6 BUZZER RUN DEG DEFM INPUT OK Buzzer sound BUZZER RUN DEG DEFM INPUT OK 1 BUZZER RUN DEG DEFM INPUT OK 1 2 BUZZER RUN DEG DEFM INPUT OK 1 2 3 BUZZER RUN DEG DEFM INPUT OK 1 2 3 4 BUZZER RUN DEG DEFM INPUT OK 1 2 3 4CHECK OK A 5 Buzzer sound OK BUZZER RUN DEG DEFM INPUT OK CHECK NG A 1 7 BRK Buzzer sound NG Printer check System 26 3652 4 1 6 PW SW 52 READY Print sample 6 CHECK ABCDEFGHIJKLMNOPQRST UVWXYZabcdefghijklmn opqrstuvwxyz0 123456 789 Q 5 lt gt 00 om rhe lt lt gt gt t 7 e788888888 8888888888888888888 END 13 Operation Check 1 When mis operation occurs return to the nearest mark and operate from the mark 2 When connecting the printer and cassette interface be sure to turn off the power switch BUZZER RUN Ready P 1 BUZZER wrt DEG 0 123456789 MODE BUZZER RUN DEG Ready 0 QWERTYUIOP BUZZER RUN QWERTYUIOP x BRK ASDFGHJKL EXT BUZZER EXT RUN ASDFGHJKL BRK ZXCVBNM BUZZER EXTRUN DEG 14 zxcvbnm IN BUZZER EXTRUN DEG w sf z xcvbnm BUZZER ExTRUN DEG zxcvbnm Z BUZZER EXT RUN te jA 14 BR K 0 123 456 789
14. m 100 ohm 1 8W 10 CR32 108 101K T TP ND 0132FBN MISCELLANEOUS 27930620 27930638 27904530 27904734 27903835 27930603 27903740 27904761 27904629 D1vD3 VR1 Diode 151588 si icon Volume for contrast 20 Kohm EVL AHAA00B24 20 DX 0273 AP 7004 23003031 27709486 Mechanical Parts Ref No Description RS Part No LCD CA51 TS Connector 126D 019 12S04 P spring A33138A 1 Seal Heat T 07 12 Seal Insulation for heat seal A47070 8 Plate Reinforcement for LCD C46480 1 Tape Adhesive for LCD A43613 5 Tape Adhesive for LCD reinforcement plate A45344 8 Connector Non direction A46359 1 Sheet Keyboard C3473 5 Tape Adhesive for PCB reinforcement plate Plate Reinforcement for PCB G707 1 C3474A 1 Assembly Film keyboard C3769A 1 Film Keyboard C3768 1 Cushion for LCD C41409 1 Seal Heat PCB G707 1 to PCB G707 2 CAX 12 3 Seal Insulation for heat seal of PCB Seal Insulation for upper keyboard film Seal Insulation for lower keyboard film f Plate Shield for volume Seal Blind for P spring C41076 1 Seal Insulation for battery non repairable Seal Insulation for RAM pack non repairable Buzzer EFB S55C41AV1 Tape Adhesive for buzzer A45381 1 Tape Adhesive for keyboard sheet A44646 1 Holder for PCB G707 1 C2373 1 Plate Shield C3500 1 Window Tandy Tape Adhesive for window C4586A 1 Case Upper for display u
15. nit C1141 5 Case Lower for display unit Tandy C1142 1 Plate Name Tandy non repairable Knob Slide C3499A 1 Spring Switch contact A46683 1 Film Common C3480 1 Spacer C3479 1 Set Keytop Tandy 21 AL 1020 AJ 7306 ARB 7642 AHC 0107 AHC 0344 AJ 4025 AHC 0346 AHC 0345 AK 0518 AHC 0347 0348 0349 0350 0351 0278 7002 2 0109 RB 6256 AHC 0111 AHC 0352 AHC 0353 Mfr s Part No 33310552 35113639 63258131 56005846 63416110 63478850 63415920 63375130 63354990 82636721 63424150 63415991 63471021 63471030 63505660 56006320 63471010 63470990 63471000 63458880 63471050 32401627 63304750 63275120 63470730 63415930 82637403 63415891 63470460 82636704 63416351 63353610 63415950 63415960 82636705 Description Holder Battery for CR1220 A35803 1 Spring Battery contact for CR1220 A35801 1 Spring Battery contact CR1220 A35800 1 Seal Insulation for battery CR1220 A46472 1 Holder for PCB G707 2 C1251 1 Holder Battery for CR2032 A35802 1 Spring Battery contact for 2032 Spring Battery contact for CR2032 Spring Battery contact for CR2032 Seal Insulation for battery CR 2032 A45154 1 Seal Insulation for battery holder A46473 1 Plate Shield for connector C4609 1 Cap Connector C4615 1 Pin Spring 2 5 mm x 12 mm Label Change for battery
16. trical Parts 5 aos ah aU iv 20 Mechanical Parts uuu u l E Es gd taco Suami pl 21 EXPLODED VIEW DISASSEMBLY INSTRUCTIONS 23 SCHEMATIC DIAGRAM Ra REA NL ee oy 24 DAI A PR 24 Keyboard ose aea o RR S ds ao em eee a 25 OR Cw eee e e CE EATUR 26 Display Display Calculation Range Program System Program Language Number of Variables RAM Capacity Program Areas Number of Stacks Subroutine FOR NEXT LOOP Operators Power Supply Power Consumption Battery Life Memory protection battery Auto Power off Ambient Temperature Dimensions Weight SPECIFICATIONS 5 x 7 dot matrix crystal 24 digit dot matrix liquid crystal display 107 9 899999999 x 10 System BASIC 26 fixed variables exclusive character variable and array variables 7520 bytes system area 672 bytes Maximum of 10 P0 through P9 8 levels 4 levels 12 levels 2 lithium batteries CR 2032 for main frame 1 lithium battery CR 1220 for memory backup Maximum 0 07W 1 Continuous program execution approximately 85 hours 2 Continuous display of 5555555555 at 68 F 20 C approximately 200 hours or 5 5 months when unit is used 1 hour per day NOTE 1 hour includes 10 minutes of condition
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