Commodore 64 – 250407 – MELIUS Rev 1.2

Commodore 64 – 250407 – MELIUS Rev 1.2

$45.00

Here’s your chance to own a brand new Commodore 64 – MELIUS Rev 1.2 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.

Revision 1.2 continues to add new features

  • Modified footprints for the Axial Electrolytic capacitors to support radial capacitors.
  • Modified Clock Oscillation circuit to minimize the amount of components in that space which resulted in 2 additional modifications:
    • Support was added for a 2nd VIC chip as well as a second crystal which makes it possible to have both a 6567 and 6569 VIC chip installed and then use jumpers to easily switch between NTSC and PAL
    • Since the 8701 clock oscillator is no longer manufactured a supporting circuit was added that requires surface mount components to support the 525 user configurable clock circuit instead. So you’ll have a choice of using those components or simply using an 8701 or 8701 replacement.
    • Created a place for the capacitor that needed to be put in place with R38, this is just above R38 and is labeled C43.
    • Tented VIAS
$

No ROMs

Include ROM Set [+$34.95]

Here’s your chance to own a brand new Commodore 64 – MELIUS Rev 1.2 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.

NEW IN THIS REVISION!!!

Revision 1.2 builds upon these modifications with the following:

  • Modified footprints for the Axial Electrolytic capacitors to support radial capacitors.
  • Modified Clock Oscillation circuit to minimize the amount of components in that space which resulted in 2 additional modifications:
    • Support was added for a 2nd VIC chip as well as a second crystal which makes it possible to have both a 6567 and 6569 VIC chip installed and then use jumpers to easily switch between NTSC and PAL
    • Since the 8701 clock oscillator is no longer manufactured a supporting circuit was added that requires surface mount components to support the 525 user configurable clock circuit instead. So you’ll have a choice of using those components or simply using an 8701 or 8701 replacement.
    • Created a place for the capacitor that needed to be put in place with R38, this is just above R38 and is labeled C43.
    • Tented VIAS

I am planning on continuously improving this board.

The production boards will use a finish known as ENIG which offers a flat surface, longer shelf life and is also lead free and RoHS compliant.

Don’t miss your opportunity to own an official DIY Chris C64 250407 MELIUS Rev 1.2

Weight 8 oz
Dimensions 9 × 16 × 1 in
Include Parts

YES, NO

Solder Parts

YES, NO

RF Modulator Bypass

MELIUS Rev 1.2 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

MELIUS REV 1.2 Memory

For memory you have 2 options.

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

SRAM

To use the SRAM circuit, you’ll need these additional components.

C26 – 0.1uF
C27 – 0.1uF
U40 –Alliance AS6C1008-55 1Mbit 55ns SRAM
U41 – 74HCT373N Tri-State Octal D-Type Latch
U42 – 74HC32 Quad 2 Input OR Gate

-OR-

DRAM

To use the DRAM circuit, you’ll need these additional components.

C25 – 0.1uF
C28 – 0.1uF
U43 – 41464
U44 – 41464

Video

MELIUS Rev 1.2 VIDEO

Revision 1.2 makes some major adjustments to the video circuit on the C64. Utilizing the same circuit as the 250425 boards, we now have enough space to add a second VIC chip allowing our board to easily swap back and forth between NTSC and PAL.

Apart from the dual VIC support, you can also choose to either supply an 8701 MOS chip for oscillation or populate the surface mount circuit.

Note that the C64 does not require 2 VIC chips, you can simply choose to install either an NTSC or PAL VIC chip and set the jumpers accordingly if you don’t want to have a system that supports both.

Surface Mount Oscillation Circuit:

*Note* All resistors and capacitors are 1206

U46 – 525-01
U47 – 74HCT1G04
C41, C42 – 0.01uF
R17, R19 – 33ohm
R16 – 10K

Supporting Components:

L1 – 2.2uH
C40 – 6.5 – 30pF
U48 – 8701 or optional Surface Mount Circuit
XTAL_NTSC – 14.31818 MHz
XTAL_PAL – 17.73447 MHz
U19 – 6567 (NTSC)
U45 – 6569 (PAL)
J_VDD, J_COLOR, J_S/LUM, J_VCC, J_XTAL, J_PAL – 3 Pin Male Headers

*All remaining components in the video section are components that would have been needed for the original 250407 build so are not included in this list.

BOM

C64 MELIUS REV 1.2 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 2114L-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 Biopolartimer
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 AS6C1008-55 SRAM DIL32 U40 SRAM
1 7432N DIL14 U42 Quad 2-input OR gate
2 41464 DRAM DIL18 U43, U44 DRAM
1 6569 VIC II DIL40 U45 Video IC PAL Version
1 74HCT1G04 SOT353 U46 Inverter
1 525-01RILF QSOP28 U47 User Configurable Clock Oscillator
1 MOS8701 DIL16 U48 Clock Oscillator
Transistors
Qty Value Package Parts Description
3 2SC1815 TO92-ECB Q1, Q2, Q8 NPN EPITAXIAL TRANSISTOR
1 TP29B/2SD880 TO220 Q3 NPN Transistor
2 BC547 TO92-CBE T1, T2 NTN Transistor
Diodes
Qty Value Package Parts Description
1 1n4371 2.7V 1N754A-DO-35-2 CR1 DIODE
1 1N754A1N754A 7.5V 1N754A-DO-35-2 CR2 DIODE
1 1n4148 DIODE-DO-35-2 CR3 DIODE
2 1n4001 DIODE-DO-35-2 CR5, CR6 Rectifier Diode
1 S2VB10 / DBA20B / DBA20C S41 CR4 Bridge Rectifier
Resistors
Qty Value Package Parts Description
1 10K R1206 R16 Resistor
2 33ohm R1206 R17, R19 Resistor
1 180R 0309/12 R31 Resistor
2 10k 0309/12 R3, R7 Resistor
3 150R 0309/12 R14, R15, R18 Resistor
2 1M 0309/12 R41, R50 Resistor
9 1k 0309/12 R4, R6, R8, R28, R29, R30, R36, R38, R100 Resistor
2 1k5 0309/12 R2, R51 Resistor
1 220R 0309/12 R12 Resistor
1 2k7 0309/12 R37 Resistor
1 390R 0309/12 R39 Resistor
5 3k3 0309/12 R1, R9, R43, R44, R45 Resistor
1 470R 0309/12 R20 Resistor
1 470k 0309/12 R35 Resistor
2 47k 0309/12 R33, R34 Resistor
1 560R 0309/12 R5 Resistor
1 5k6 0309/12 R10 Resistor
1 68R 0309/12 R11 Resistor
1 75R 0309/12 R13 Resistor
1 82ohm 0309/12 R42 Resistor
1 1k 3296W RV1 Variable Resistor
1 220R 3296W RV2 Variable Resistor
Resistor Packs
Qty Value Package Parts Description
2 33ohm SIL8 RP1, RP2 Resistor Pack
1 3k3 SIL8 RP3 Resistor Pack
1 3k3 SIL10 RP4 Resistor Pack
Capacitors
Qty Value Package Parts Description
2 .01uF C1206 C41, C42 Ceramic Capacitor
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
3 0.22uF C050-025X075 C36, C92, C100 Ceramic Capacitor
1 1000pf C050-025X075 C37 Ceramic Capacitor
1 51pf 0309/12 C38 Ceramic Capacitor
4 .1uf C050-025X075 C39, C66, C67, C105 Ceramic Capacitor
1 220pF 0309/12 C43 Ceramic Capacitor
2 1800pf C050-025X075 C48, C93 Ceramic Capacitor
1 68pf C050-025X075 C55 Ceramic Capacitor
1 .22 25v C050-025X075 C97 Ceramic Capacitor
1 2200uf 25v E45-16 C19 Electrolytic Capacitor
13 10uf 25v E5-5 C8, C12, C13, C14, C15, C17, C24, C34, C57, C62, C65, C94, C102 Electrolytic Capacitor
1 1000uf E45-16 C88 Electrolytic Capacitor
1 470uf 25v E45-16 C90 Electrolytic Capacitor
1 100uf 25v E5-5 C91 Electrolytic Capacitor
1 6.5 – 30pF CTRIM3050.505 C40 Trimm 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
1 Header Assy, 3 Pin 1×3 CN10 PIN HEADER
Misc
Qty Value Package Parts Description
2 2.2uH 0309/12 L1, L2 Inductor
1 10uH SU-10VD L4 Line Filter
1 1.2uH 0309/12 L5 Inductor
1 10uH 0309/12 L6 Inductor
16 1X03 B-A13, B-A14, B-A15, C-A12, C-A13, C-A14, C-A15, CN10, J_COLOR, J_S/LUM, J_VCC, J_VDD, J_XTAL, K-A13, K-A14, K-A15 PIN HEADER
1 1X02 J_PAL PIN HEADER
1 SH32 F1 FUSE HOLDER 6 x 32 mm
20 FB0309/12 FB1, FB2, FB3, FB4, FB5, FB7, FB8, FB9, FB10, FB11, FB12, FB13, FB14, FB15, FB18, FB19, FB20, FB21, FB22, FB23 Ferrite Bead
1 14.31818 NTSC C64-CRYSTAL-Y1 XTAL_NTSC NTSC Crystal
1 17.73447 PAL C64-CRYSTAL-Y1 XTAL_PAL PAL Crystal
1 300AWDP1J1BLKM7QE-ND R8017L-R21 SW1 Power Switch
2 MC7805CT TO220 VR1 Voltage Regulator
1 MC7812CT TO220 VR2 Voltage Regulator

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