;------------------------------------ ; Dream 6800 brief construction notes ;------------------------------------ Welcome to the construction notes for this slightly modified version of the 1978 DREAM6800 by MJ Bauer. The main changes centre around the upgrading of the original 2708 EPROM to a 2716/2732 permitting a single 5v power supply design, the PSU has been redesigned to use a fixed 5v buck switching regulator allowing for cool running and wider input voltage range. The final change was to upgrade address decoding logic to permit the use of UM6116 2k byte chips this gives a total of 4k byte RAM whilst keeping to vintage style IC's. The parts list below provides a list of all parts required, notes have been added to indicate component specifics such as lead pitch, dielectric type etc... Part numbers have not been supplied except for the more difficult parts to source where a parts list notes section shows the various suppliers I used to obtain these parts. Some parts such as the keyboard and speaker were obtained from Ebay, I know no other supplier for these specific parts. It is highly recommended to proceed with the build in a structured manner whilst referring to the original DREAM6800 documentation and revised schematics :- 1) Inspect the PCB for any damaged traces using a magnifying glass if necessary. 2) Fit one value of the component type at a time, double checking your work as you go. Start with capacitors, then resistors, then IC sockets etc.. DO NOT FIT IC'S !!!! 3) DIL sockets are highly recommended for all IC's, removing soldered IC's can be tricky!!! 4) I would recommend making a little cardboard insulating washer to fit under oscillator crystal. 5) I have insulated the switching regulator from the heatsink but this is not strictly necessary. 6) Apply 12v DC power and verify switching regulator operation (5v output) 7) Insert all IC's and verify operation using original documentation. *** Note *** Resistor R19 may need adjustment to get the NE566 VCO to oscillate at 2400hz In my board I found that 10k ohm gave correct operation Finally, I hope the board brings you many hours of nostalgic fun Regards David Fry ;---------------- ; COMPONENT LIST ;---------------- ;------------ ; Capacitors ;------------ | C1,C9 150pF 5mm Pitch Ceramic | C2 2.2uF 2.5mm Pitch Tant | C3 10uF 2.5mm Pitch Tant | C4 33nF 5mm Pitch Film | C5,C8 10nF 5mm Pitch Film | C6 1nF 5mm Pitch Film | C7 22nF 5mm Pitch Film | C10 3n3 5mm Pitch Ceramic | C12 47pf 5mm Pitch Ceramic | C13,C16,C17 100uF 2.5mm Pitch Low Imp Elect | C14 1500uF 5mm Pitch Low Imp Elect | C15,C18,C35 22uF 2.5mm Pich Tant | C11,C19,C20 100nF 5mm Pitch MLCC Ceramic | C21,C22,C23 | C24,C25,C26 | C27,C28,C29 | C30,C31,C32 | C33,C34 | C36 1uF 2.5mm Pitch Tantalum (Low Imp Elect) ;----------- ; Resistors ;----------- | R1 1k All resistors are 0.25w metal film | R2 100R | R3,R7,R20 4k7 | R6 47 | R8,R26 470 | R4,R5,R9 2k2 | R22,R27,R29 | R10,R25 220 | R11,R14,R18 10k | R23,R28 | R12,R13 22k | R15,R16,R17 1k5 | R19 5k6 (10k) Adjust for 2.4Khz osc tone | R21 6k8 | R24 120 | R30 75 | R31 10 | RV1 5k ;---------------- ; Semiconductors ;---------------- | D1,D2,D3 1N4148 | D4 | D5 BAT43 | D6 1N5402 | D7 MBR350 | D8 1N4002 (1A Std Rectifier) | Q1 2N3906 | Q2 2N3904 | U1 MC6800 | U2 2716 (Or 2732 EPROM) | U3,U4 6116 | U5,U6 74LS367 | U7 CD4014 | U8 MC6875 | U9 MC6821 | U10 74LS10 | U11,U17 74LS04 | U12 74LS08 | U13 CD4040 | U14,U15 74LS93 | U16 74LS20 | U18 74LS11 | U19 74LS123 | U20 7440 *** SEE PART NOTES *** | U21 74LS74 | U22 74121 *** SEE PART NOTES *** | U23 LM741 | U24 NE566 *** SEE PART NOTES *** | U25 74LS138 | U26 LM2576-5.0 *** SEE PART NOTES *** | U27 LT1054 *** SEE PART NOTES *** | X1 4Mhz *** SEE PART NOTES *** | J1 Video_Out *** SEE PART NOTES *** | J2 180_DIN *** SEE PART NOTES *** | L1 10uH Axial *** SEE PART NOTES *** | L2 120uH *** SEE PART NOTES *** | CON1 12v DC *** SEE PART NOTES *** | P1 EPROM 3 pin 0.1" header | P2 Spkr 3 pin 0.1" Molex KK connector | P3 I/O Pins 8 pin 0.1" Molex KK connector | P4 Key Matrix 8 pin 0.1" Molex KK connector | P5 Keys 3 pin 0.1" Molex KK connector | P6 Expansion NOT FITTED ;------------- ; PARTS NOTES ;------------- Due to obsolesence some parts for this project are either tricky to locate or are component footprint specific, here is a list of suppliers and part numbers from where I obtained these parts.. It maybe that you can locate these parts elsewhere, but I doubt it will be possible to obtain all parts from a single supplier... ;;; DIGIKEY PARTS https://www.digikey.co.uk/ -RV1- 5k Preset Resistor 3386H-1-502LF 3386H-502LF-ND -L1- FIXED IND 10UH 370MA 750 MOHM 78F100J-RC M10135-ND -L2- FIXED IND 120UH 3.2A 82 MOHM AIUR-15-121K AIUR-15-121K-ND -U26- IC REG BUCK 5V 3A TO220-5 LM2576T-5.0/NOPB LM2576T-5.0/NOPB-ND -D7- DIODE SCHOTTKY 50V 3A DO201AD MBR350RLG MBR350RLGOSCT-ND -D5- DIODE SCHOTTKY 30V 200MA DO35 BAT43 497-2492-1-ND -D6- DIODE GEN PURP 200V 3A DO201AD 1N5402RLG 1N5402RLGOSCT-ND -X1- CRYSTAL 4.0000MHZ SERIES T/H ECS-40-S-1 X081-ND -CON1- 2.1mm Power Jack EJ508A EJ508A-ND -C14- 1500uF 25v SMPS Capacitor UHW1E152MHD 493-6948-ND HEATSINK TO220 530614B00000G HS278-ND -J1- CONN RCA JACK MONO 3.2MM R/A PJRAN1X1U04X PJRAN1X1U04X-ND ;;; UTSOURCE PARTS https://uk.utsource.net/ -U24- NE566 -U27- LT1054 ;;; EBAY PARTS (Use Advanced Search by keyword & seller) -J2- 5 PIN DIN PCB SKT Ebay seller - lyn3009 20 KEY HEX KEYBOARD ASSY Ebay seller - wonderco_buy 57mm 8OHM SPEAKER Ebay seller - szdepot88 -U20- 7440 TTL Ebay seller - vila_restor -U22- 74121 TTL Ebay seller - vila_restor