Commodore 64 – 250407 – MELIUS Rev 1.1

$35.00

Here’s your chance to own a brand new Commodore 64 – MELIUS Rev 1.1 main board. The revision is 250407, Artwork 251137.

Project MELIUS is dedicated to improving the original Commodore 64 while staying as true to the original as possible.

This first iteration of project MELIUS boards features the following improvements:

  • RF Modulator Bypass Circuitry – This modification allows you to be free from the RF modulator component by soldering a handful of components to the board which will bring you an improved quality video signal. You can also choose to use the original RF modulator instead. Your choice.
  • EEPROM upgrades – The Basic, Kernal and Character ROM’s have been replaced with 27C512 EEPROM’s. This means that you can burn a ROM and directly plug it into your C64’s mainboard. What’s even better is that because the 27C512 have 64K of space, you can store up to 8 ROM images for both Basic and Kernal ROM’s and up to 16 variations of the character ROM and then quickly select between them by moving around some jumpers.
  • Connector Footprint Updates – This will help with hunting down various connectors for the IEC, A/V and power ports. Especially the power port connectors. Finding these with the 5mm pin spacing for the ground shield is very difficult. This allows you to easily pop in modern replacements.

Revision 1.1 builds upon these modifications with the following:

  • RF Modulator Bypass Circuitry – The first revision had a footprint issue for the 2 transistors used in the circuit. This revision corrects that error.
  • Memory – The existing layout of the 8 4164 DRAM chips has been modified to the following:
    • 2 41464 DRAM chips to provide legacy support and maintain a small footprint.
    • A modern SRAM replacement circuit has been added that can be used instead of the 2 41464 DRAM memory chips.

This is the first production turn of MELIUS Rev 1.1 which means that these boards use a finish known as ENIG which offers a flat surface, longer shelf life and is also lead free and RoHS compliant.

Available on backorder

$

Here’s your chance to own a brand new Commodore 64 – MELIUS Rev 1.1 main board. The revision is 250407, Artwork 251137.

Project MELIUS is dedicated to improving the original Commodore 64 while staying as true to the original as possible.

The first iteration of project MELIUS boards featured the following improvements:

  • RF Modulator Bypass Circuitry – This modification allows you to be free from the RF modulator component by soldering a handful of components to the board which will bring you an improved quality video signal. You can also choose to use the original RF modulator instead. Your choice.
  • EEPROM upgrades – The Basic, Kernal and Character ROM’s have been replaced with 27C512 EEPROM’s. This means that you can burn a ROM and directly plug it into your C64’s mainboard. What’s even better is that because the 27C512 have 64K of space, you can store up to 8 ROM images for both Basic and Kernal ROM’s and up to 16 variations of the character ROM and then quickly select between them by moving around some jumpers.
  • Connector Footprint Updates – This will help with hunting down various connectors for the IEC, A/V and power ports. Especially the power port connectors. Finding these with the 5mm pin spacing for the ground shield is very difficult. This allows you to easily pop in modern replacements.

Revision 1.1 builds upon these modifications with the following:

  • RF Modulator Bypass Circuitry – The first revision had a footprint issue for the 2 transistors used in the circuit. This revision corrects that error.
  • Memory – The existing layout of the 8 4164 DRAM chips has been modified to the following:
    • 2 41464 DRAM chips to provide legacy support and maintain a small footprint.
    • A modern SRAM replacement circuit has been added that can be used instead of the 2 41464 DRAM memory chips.

This is the first production turn of MELIUS Rev 1.1 which means that these boards use a finish known as ENIG which offers a flat surface, longer shelf life and is also lead free and RoHS compliant.

RF Modulator Bypass

To use the RF modulator bypass circuit you’ll need these additional components.

T1, T2 – BC547
R14, R15, R18 – 150 ohm 1/2 watt
R8 – 1K
R9 – 3.3K
R10 – 5.6K
R11 – 68 ohm
R12 – 220 ohm
R13 – 75 ohm
R20 – 470 ohm
L6 – 10uH
CR3 – 1N4148
C35 – 330pF
C55 – 68pF

Optional:

You can choose to get these 2 trimmer resistors but they are not necessary. When not using the trimmer resistors you can close solder bridges at SJ1 and SJ2.

RV1 – 1K Multi-turn Trimmer
RV2 – 220 ohm Multi-turn Trimmer

EEPROMs

Downloads:

How to concatenate ROM images:

In Windows you would simply use the following command:

copy /b romfile1.bin+romfile2.bin romfilecombined.bin

ROM Jumper Settings:

2021.07.14-MELIUS-ROM-JUMPER-SETTINGS

Memory

For memory you have 2 options.

  1. Legacy 41464 DRAM. The same memory that is used in the 250469 boards or..
  2. SRAM

Legacy 41464 DRAM:

U43 – 41464-10 DRAM 256Kbit 64Kx4

U44 – 41464-10 DRAM 256Kbit 64Kx4

C25 – 0.1uF

C28 – 0.1uF

 

SRAM:

U40 – Alliance AS6C1008-55PIN 1Mbit 55ns SRAM

U41 – SN74HCT573N Tri-State Octal D-Type Latch

U42 – SN74HC32 Quad 2 Input OR Gate

C26 – 0.1uF

C27 – 0.1uF

BOM

C64 MELIUS REV 1.1 BOM
         
Integrated Circuits
Qty Value Package Parts Description
1 6526 CIA DIL40 U1, U2 Complex Interface Adapter
3 W27C512 DIL28 U3, U4, U5 Basic / Kernal / Char ROMS
1 2114-20 RAM DIL18 U6 Color RAM
1 6510 Micro Processor DIL40 U7 Micro Processor
1 74LS06N DIL14 U8 Hex Inverter
1 74LS257 DIL16 U13 Multiplexer
1 74LS258 DIL16 U14 Multiplexer
1 74LS139 DIL16 U15 Decoder / Demultiplexer
1 4066N DIL14 U16 Quad bilateral ANALOG SWITCH
1 82S100 PLA DIL28 U17 C64 PLA
1 6581 SID DIL28 U18 SID Sound IC
1 6567 VIC-II DIL40 U19 Video IC NTSC Version
1 LM556 DIL14 U20 General Purpose Bioplartimer
1 74LS257 DIL16 U25 Multiplexer
2 74LS373 DIL20 U26, U41 Octal D type transparent LATCH, edge triggered
1 74LS08 DIL14 U27 Quad 2-input AND gate
1 4066N DIL14 U28 Quad bilateral ANALOG SWITCH
1 74LS74 DIL14 U29 Flip Flop
1 74LS193 DIL16 U30 Binary Counter
1 74LS629 DIL16 U31 Dual Voltage Controlled Oscillator
1 MC4044 DIL14 U32 Phase Frequency Detector
1 AS6C1008-55 SRAM DIL32 U40 SRAM
1 7432N DIL14 U42 Quad 2-input OR gate
2 41464 DRAM DIL18 U43, U44 DRAM
         
         
Transistors
Qty Value Package Parts Description
3 2SC1815 TO92-ECB Q1, Q2, Q8 NPN EPITAXIAL TRANSISTOR
1 TP29B/2SD880 TO220 Q3 NPN Transistor
1 PN2222A TO92-ECB Q7 NPN Transistor
2 BC547 TO92-CBE T1, T2 NPN Transistor
         
         
Diodes
Qty Value Package Parts Description
1 1n4371 2.7V 1N754A-DO-35-2 CR1 Zener Diode
1 1N754A1N754A 7.5V 1N754A-DO-35-2 CR2 Zener Diode
1 1n4148 DIODE-DO-35-2 CR3 Zener Diode
1 S2VB10 / DBA20B/ DBA10C S41 CR4 Bridge Rectifier
2 1n4001 DIODE-DO-35-2 CR5, CR6 Rectifier Diode
         
         
Resistors
Qty Value Package Parts Description
5 3k3 0309/12 R1, R9, R43, R44, R45 Resistor
1 5k6 0309/12 R10 Resistor
1 68R 0309/12 R11 Resistor
1 220R 0309/12 R12 Resistor
2 180R 0309/12 R13, R31 Resistor
3 150R 0309/12 R14, R15, R18 Resistor
1 1k2 0309/12 R17 Resistor
1 15k 0309/12 R19 Resistor
2 1k5 0309/12 R2, R51 Resistor
1 470R 0309/12 R20 Resistor
1 100R 0309/12 R26 Resistor
1 500R S75P R27 Potentiometer
2 10k 0309/12 R3, R7 Resistor
2 47k 0309/12 R33, R34 Resistor
1 470k 0309/12 R35 Resistor
1 2k7 0309/12 R37 Resistor
2 390R 0309/12 R39, R53 Resistor
10 1k 0309/12 R4, R6, R8, R16, R28, R29, R30, R36, R38, R100 Resistor
2 1M 0309/12 R41, R50 Resistor
1 82R 0309/12 R42 Resistor
1 560R 0309/12 R5 Resistor
1 300R 0309/12 R52 Resistor
2 33R SIL8 RP1, RP2 Resistor Pack
1 3k3 SIL8 RP3 Resistor Pack
1 3k3 SIL10 RP4 Resistor Pack
1 1k 3296W RV1 Variable Resistor
1 220R 3296W RV2 Variable Resistor
         
         
Capacitors
Qty Value Package Parts Description
38 .1uf C050-025X075 C1, C2, C3, C4, C5, C6, C7, C9, C16, C18, C22, C25, C28, C29, C30, C31, C32, C33, C44, C45, C46, C47, C49, C50, C51, C52, C53, C54, C59, C60, C89, C95, C96, C98, C99, C101, C103, C200 Ceramic Capacitor
2 470pf C050-025X075 C10, C11 Ceramic Capacitor
2 .22 100v 0309/12 C20, C21 Ceramic Capacitor
1 82pf 0309/14 C203 Ceramic Capacitor
1 360pf 0309/12 C23 Ceramic Capacitor
2 .1uf C050-025X075 C26, C27 Ceramic Capacitor
1 330pf C050-025X075 C35 Ceramic Capacitor
1 20pf 50v 0309/12 C36 Ceramic Capacitor
1 1000pf C050-025X075 C37 Ceramic Capacitor
1 51pf 0309/12 C38 Ceramic Capacitor
9 .1uf C050-025X075 C39, C56, C66, C67, C68, C74, C82, C84, C105 Ceramic Capacitor
2 1800pf C050-025X075 C48, C93 Ceramic Capacitor
1 68pf C050-025X075 C55 Ceramic Capacitor
1 10pf C050-025X075 C70 Ceramic Capacitor
1 33pf 50v 0309/12 C83 Ceramic Capacitor
1 .47uf C050-025X075 C85 Ceramic Capacitor
1 39pf 50v 0309/12 C86 Ceramic Capacitor
2 0.22uF C050-025X075 C92, C100 Ceramic Capacitor
1 .22 25v C050-025X075 C97 Ceramic Capacitor
15 10uf 25v E5-5 C8, C12, C13, C14, C15, C17, C24, C34, C57, C62, C65, C94, C102, C107, C108 Electrolytic Capacitor
1 2200uf E45-16 C19 Electrolytic Capacitor
1 1000uf E45-16 C88 Electrolytic Capacitor
1 470uF 25v E45-16 C90 Electrolytic Capacitor
1 100uf 16v E5-5 C91 Electrolytic Capacitor
         
         
Connectors
Qty Value Package Parts Description
1 Header Assy, 20 Pin 1X20 CN1 PIN HEADER
1 6 Pin DIN MAB6H-2M CN4 Female CONNECTOR
1 8 Pin DIN 838_DIN8-M2 CN5 Female CONNECTOR
1 44 Pin Card Edge FE100-22-2 CN6 Female CONNECTOR
1 7 Pin DIN C64-DIN-CN7-M2 CN7 Female CONNECTOR
2 Plug Assy, 9 Pin MINID 177-009-MALE CN8, CN9 SUB-D
11   1X03 B-A13, B-A14, B-A15, C-A12, C-A13, C-A14, C-A15, CN10, K-A13, K-A14, K-A15 PIN HEADER
         
         
Misc
Qty Value Package Parts Description
1 2.2uH 0309/12 L2 Inductor
1 10uH SU-10VD L4 Line Filter
1 1.2uH 0309/12 L5 Inductor
1 10uH 0309/12 L6 Inductor
1 Fuse Holder SH32 F1 Fuse Holder 6 x 32 mm
22   FB0309/12 FB1, FB2, FB3, FB4, FB5, FB7, FB8, FB9, FB10, FB11, FB12, FB13, FB14, FB15, FB16, FB17, FB18, FB19, FB20, FB21, FB22, FB23 Ferrite Bead
1 300AWDP1JBLKM7QE-ND R8017L-R21 SW1 Power Switch
1 MC7805CT TO220 VR1 Voltage Regulator
1 MC7812CT TO220 VR2 Voltage Regulator
1 14.31818 NTSC C64-CRYSTAL-Y1 Y1 NTSC Crystal

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