;------------------------------------
; 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








