PCB and components arrived. So many packages, from US, Spain, Czech Republic and China. I bought two sets of PCBs, and they are slightly different. Checking the components and comparing with the PCB footprints I figured out the DIN8 connectors will not fit and need to order new ones. The rest seems to be OK.
The only package that actually costed me a lot of taxes was the one sent by Mouser Electronics. That is because they only use Fedex to send their packages and there is no way around import taxes when using Fedex, the delivery guy comes with a portable credit card machine to charge you 110% of taxes before handle you the package.
<sarcasm>Thanks DRF, love you!</sarcasm>. Anyways, we can start building the MSX now.
I’ll start building the Keyboard, and in this post I’ll document every component I had to buy for the whole build. If you are interested in building a MSX computer or just need a reference for a specific component, you can use the lists I’m documenting here.
Building The Keyboard
For the keyboard I will start building the leveling elements, connecting them to the board and then soldering all resistors, diodes, capacitors, sockets, connectors, and key switches. Then we will fit the key caps appropriately.
First step is to setup the leveling kit that is used with the big keys on the keyboard as well as with the space key. First thing I need to say is that it is not a super easy thing. Those kits are formed by small plastic pieces that need to be mounted in a specific order and side, then the metal bars need to slide into those in the right way, so you get the expected leveling without breaking the plastic.
There is a way to connect the keys to the keyboard that you don’t need force anything. If you are forcing the connection, you are doing the wrong way and the plastic may break.
Keep in mind that you need to slide the small piece of plastic into the big one in a way that you keep the side with the two holes pointing to the place where you will hold the bar. The metal bar slides into the lowest hole.
A good video to understand how to build the stabilizer is available below. I just ignored the tip to cut parts of the pieces. My kit worked very well without any of those recommended changes.
When setting up the stabilizers into the board, connect the big part to the larger hole and gently push the other side of the plastic piece against the smaller hole. You will hear a click and the stabilizer will be mounted to the board.
After setting up the stabilizers and mount those into the board, we can move forward and start soldering the three through-hole 470 ohm resistors to the keyboard. Those are specific as R1, R2 and R3 and have no polarity.
The resistor array (RN1) is a 6 pin 4.7K ohm component that also goes into the board. Go ahead and solder it. As a tip use a piece of tape to hold it and turn the board, solder the first and the last pin, turn over remove the tape, make sure everything is aligned and then solder the rest of the pins.
There are three capacitors to be soldered. Two 0.1 uF, MLCC (C1 and C2) and one 10uF MLCC (C3). Those are not polarized and are located on the superior part of the board.
You will need to solder a 16dip300 socket and a 14dip300 socket to the board. They are also located on the superior part and will hold the logic chips used by the keyboard. The same strategy I explained for the resistor array can be used here. Just use a piece of tape to hold the sockets in place, turn the board and solder the first and the last pin.
Then remove the tape, adjust the socket to the right position (you may need to de-solder a pin) and solder the rest.
The picture below shows the keyboard so far.
Use the same strategy used for the sockets to solder the connector as well. It is a 2×8 pin header, right angle shrouded connector with 2.54mm pitch. It will be used to connect the keyboard to the mainboard using a flat table.
LEDs have polarity and need to be soldered in the right way. Usually, boards are marked with a squared sign where you need to solder the cathode (negative) but the thing is that some boards I soldered before were just the inverse. Apparently, there is no real standard and I usually use my multimeter to detect where is the cathode, putting a probe on the ground and checking the place where the led needs to be soldered. I could only do that to the LED indicated as D1 on the board.
I believe the other LEDs are only activated when you have power on the board and are used to indicate status of specific keys as they are located just under two of them. I’ll come back later and solder those when the boards are connected.
For the space key I bought a better switch from Mouser and that one was super easy to solder. It has small plastic connectors that fit perfectly to the board and leave just the connectors to solder. But the rest of the keys I purchased from AliExpress, and they don’t have those connectors.
They are just fixed by the contacts, and it is a problem to keep them aligned when soldering. The strategy I used was to go four by four using a tape to hold them in position, then turning the board and soldering just one pin. Then I used the solder iron and my hand to kind of align then before soldering the other pin.
It was just a lot of work to get everything aligned but the result was good.
I also didn’t like the fact that my AliExpress source provided different tons of brown for the switches. I believe they are all from the same quality (not super good), and after placing the keycaps nobody is going to notice, but it is annoying to see different tonalities when it is supposed to be just one.
Here is a picture of the almost finished keyboard and a time lapse of the whole process.
Bill of Materials (Reference)
To help others that may be interested on the project I’m pasting Sergey’s BoM here with the links I used to buy the components. Most of them are available from Mouser, UTSource and/or AliExpress. For the main board, I decided to use the Mouser automatic project cart shared by Sergey on his website here, but I’m also including links to the same components on AliExpress if you prefer to deal with them.
Keyboard components I purchased from AliExpress following the links I’m providing below.
|Type||Reference||Description||Quantity||Possible sources and notes|
|PCB||Omega Keyboard PCB||1||You have multiple options here. (1) You can download the Gerber files from Sergey’s GitHub repo, create a zip and order minimum of 5 PCBs from PCBWay. (2) You can buy one of the spare boards from MSXMakers. (3) You can buy from eBay sellers, like those option 1/option 2.|
|Integrated Circuit||U1||74LS145 Octal D-Type Latch||1||AliExpress|
|Integrated Circuit||U2||74LS07 Octal Bus Transceiver||1||AliExpress|
|LED||D1||3 mm, green LED indicator||1||AliExpress|
|LED||D2||3 mm, yellow LED indicator||1||AliExpress|
|LED||D3||3 mm, red LED indicator||1||AliExpress|
|Keyboard Switch||SW1-SW73||MX Cherry – Linear||73||Make sure you purchase the 5 pin version as it is going to be easier to align the keys on the keyboard when soldering.|
|Switch Leveling Kit||SW13, SW49, SW64, SW65, SW73||Leveling kit for MX 1×2, 1×2.25, 1×2.75||5||AliExpress|
|Keycaps||SW1-SW73||104 Keycaps kit for Cherry MX Keyboard||1||You have a lot of options here, here are a few alternatives on AliExpress:|
|Connector||J1||2×8 pin header, right angle, shrouded, 2.54 mm pitch||1||AliExpress|
Mouser 710-61201621721 or use 2×8 pin female header to plug the keyboard directly to the mainboard using 15 mm standoffs between them: Mouser 200-ESQ10812LD
|Capacitor||C1, C2||0.1 uF, MLCC, 5 mm lead spacing||2||AliExpress|
|Capacitor||C3||10 uF, MLCC, 5 mm lead spacing||1||AliExpress|
|Resistor Array||RN1||4.7 kohm, bussed, 6 pin SIP||1||AliExpress|
|Resistor||R1 – R3||470 ohm, through hole||3||AliExpress|
|Type||Reference||Description||Quantity||Source and notes|
|PCB||Omega Mainboard PCB||1||You have multiple options here. (1) You can download the Gerber files from Sergey’s GitHub repo, create a zip and order minimum of 5 PCBs from PCBWay. (2) You can buy one of the spare boards from MSXMakers. (3) You can buy from eBay sellers, like those option 1/option 2. Either way, pay attention to the footprints to make sure you are buying the correct connectors (specially the DIN8 used for RGB and Cassette ports)|
|Integrated Circuit||U1||Z80 CPU, CMOS, 40 pin DIP – Z84C00xxPEG||1||Take care here. I bought one Z80 from an eBay package that was supposed to have all Omega MSX “hard to find” components and it didn’t work. Then I bought two from UTSource that worked flawlessly. I would recommend UTSource to buy the Z80 (make sure you get the new ones, not used).|
|Integrated Circuit||U2||82C55 PPI, CMOS, 40 pin DIP – CP82C55AZ||1||eBay package, AliExpress|
|Integrated Circuit||U3||V9958 VDP, 64 pin DIP||1||I bought mine from an eBay package. But just figured out the seller is not including VDPs anymore. That is a hard one to buy cause there are lots of defective chips, used, in bad condition, etc. I recommend UTSource or trusted AliExpress sellers. Don’t choose the cheapest ones in AliExpress or you will have to return them.|
|Integrated Circuit||U4||YM2149 PSG, 40 pin DIP or AY-3-8910||1||eBay package, AliExpress|
|Integrated Circuit||U5||RP5C01 RTC, 18 pin DIP||1||eBay package, AliExpress|
|Integrated Circuit||U6||512 KiB Flash ROM, 32 pin DIP – SST39SF040||1||AliExpress|
|Integrated Circuit||U7||512 KiB SRAM, 32 pin DIP – AS6C4008||1||AliExpress|
|Integrated Circuit||U8 – U11||D41464, 64K x 4 DRAM, 18 pin DIP||4||eBay package, AliExpress|
|Integrated Circuit||U12 – U14||Simple Programmable Logic Device – ATF16V8B||3||AliExpress|
|Integrated Circuit||U15 – U18||4-by-4 Register File – 74HC670, 16 pin DIP||4||AliExpress|
|Integrated Circuit||U19 – U21||74F541, 20 pin DIP||3||AliExpress|
|Integrated Circuit||U22||74HCT540, 20 pin DIP||1||AliExpress|
|Integrated Circuit||U23, U24||74HCT273, 20 pin DIP||2||AliExpress|
Mouser 595-SN74HCT273N. Note U24 is optional – printer port support.
|Integrated Circuit||U25, U26||74F245, 20 pin DIP||2||AliExpress|
|Integrated Circuit||U27||74HCT175, 16 pin DIP||1||AliExpress|
|Integrated Circuit||U28, U29||74HCT157, 16 pin DIP||2||AliExpress|
|Integrated Circuit||U30, U31||74HCT153, 16 pin DIP||2||AliExpress|
|Integrated Circuit||U32||74AHCT138, 16 pin DIP||1||AliExpress|
|Integrated Circuit||U33||74AHCT125, 14 pin DIP||1||AliExpress|
Mouser 595-SN74AHCT125N. Note U33 is optional – printer port support.
|Integrated Circuit||U34 – U36||Dual Flip Flop – 74HCT74, 14 pin DIP||3||AliExpress|
|Integrated Circuit||U37 – U39||74AHCT32, 14 pin DIP||3||AliExpress|
|Integrated Circuit||U40, U41||74HCT30, 14 pin DIP||2||AliExpress|
|Integrated Circuit||U42||74LS07, 14 pin DIP||1||AliExpress|
|Integrated Circuit||U43||74HCT04, 14 pin DIP||1||AliExpress|
|Integrated Circuit||U44||74AHCT02, 14 pin DIP||1||AliExpress|
|Integrated Circuit||U45||74HCT00, 14 pin DIP||1||AliExpress|
|Integrated Circuit||U46||Microprocessor Supervisory Circuit – ADM691A||1||AliExpress |
Mouser 584-ADM691AANZ; Possible alternatives: MAX691, LTC691, ADM691
|Integrated Circuit||U47||Sony CXA1645P RGB Encoder, 24 pin DIP-400||1||eBay package, AliExpress|
|Integrated Circuit||U48||MCP6281-E/P Operational Amplifier, 8 pin DIP||1||AliExpress|
|Integrated Circuit||U49||LM311N, Voltage Comparator, 8 pin DIP||1||AliExpress |
Mouser 926-LM311N-NOPB. Note U49 is optional – cassette recorder support.
|Capacitor||C1 – C58||0.1 uF, MLCC, 5 mm Pitch||58||AliExpress|
|Capacitor||C59 – C64||220 uF, Electrolytic||6||AliExpress|
Mouser 647-UBW1E221MPD. Note C62 – C64 optional – RGB output support
|Capacitor||C65 – C67||100 uF, 16V, Aluminum Organic Polymer||3||Part of the kit bought previously (AliExpress)|
|Capacitor||C68 – C70||10 uF, MLCC, 5 mm Pitch||3||AliExpress|
Mouser 810-FG28X5R1E106MR00. Note C71 optional – cassette recorder support.
|Capacitor||C71 – C77||10 uF, Electrolytic||7||Part of the kit bought previously (AliExpress)|
Mouser 647-UPW1E100MDD1TD. Note C71 optional – cassette recorder support.
|Capacitor||C78||1 uF, Electrolytic||1||Part of the kit bought previously (AliExpress)|
Mouser 710-860020672005. Note C78 optional – cassette recorder support.
|Capacitor||C79, C80||22 nF, MLCC, 5 mm Pitch||2||AliExpress|
Mouser 810-FG28X7R1H223KNT0. Note C79, C80 optional – cassette recorder support.
|Capacitor||C81||1.5 nF, MLCC, 5 mm Pitch||1||AliExpress|
|Capacitor||C82 – C84||330 pF, MLCC, 5 mm Pitch||3||AliExpress|
|Capacitor||C85||47 pF, MLCC, 5 mm Pitch||1||AliExpress|
|Capacitor||C86, C87||33 pF, MLCC, 5 mm Pitch||2||AliExpress|
|Capacitor||C88 – C90||30 pF, Trim Capactiors, 5 mm Pitch||3||AliExpress|
Mouser 659-GKG30015. Note: Can be replaced with Mouser 810-FG28C0G2A270JNT0 if color subcarrier frequency tunning is not required.
|Capacitor||C91||27 pF, MLCC, 5 mm Pitch||1||AliExpress|
Mouser 810-FG28C0G2A270JNT0. Note C91 should be 18 pF for PAL support.
|Capacitor||C92, C93||22 pF, MLCC, 5 mm Pitch||2||AliExpress|
|Capacitor||C94||4.7 pF, MLCC, 5 mm Pitch||1||AliExpress|
|Resistor Array||RR1 – RR4||10 kohm, bussed, 10 pin SIP||4||AliExpress|
Mouser 652-4610X-1LF-10K or Mouser 652-4610X-AP1-103LF
|Resistor Array||RR5 – RR7||4.7 kohm, bussed, 10 pin SIP||3||AliExpress|
Mouser 652-4610X-1LF-4.7K or Mouser 652-4610X-AP1-472LF
|Resistor Array||RR8, RR10||4.7 kohm, bussed, 6 pin SIP||1 (2)||AliExpress|
Mouser 652-4606X-1LF-4.7K or Mouser 652-4606X-AP1-472LF. Note RR10 is optional – Memory pager size workaround.
|Resistor Array||RR9||470 ohm, bussed, 6 pin SIP||1||AliExpress|
Mouser 652-4606X-1LF-470 or Mouser 652-4606X-AP1-471LF
|Resistor||R1||1 Mohm, axial||1||AliExpress|
Mouser 603-MFR-25FBF52-1M. Note R1 is optional – PAL support.
|Resistor||R2, R3||470 kohm, axial||2||AliExpress|
|Resistor||R4||220 kohm, axial||1||AliExpress|
|Resistor||R5, R6||100 kohm, axial||2||AliExpress|
|Resistor||R7, R8||47 kohm, axial||2||AliExpress|
|Resistor||R9, R10||20 kohm, 1% tolerance, axial||2||AliExpress|
Mouser 603-MFR-25FBF52-20K. Note R9 should be 16 kohm, 1% for PAL support.
|Resistor||R11 – R14||10 kohm, axial||4||AliExpress|
Mouser 603-MFR-25FBF52-10K. Note R11, R12 are optional – cassette recorder support. Note R14 is optional – RGB output support.
|Resistor||R15||5.6 kohm, axial||1||AliExpress|
|Resistor||R16 – R22||4.7 kohm, axial||7||AliExpress|
Mouser 603-MFR-25FBF52-4K7. Note R18 – R20 are optional – cassette recorder support.
|Resistor||R23, R24||2.7 kohm, axial||2||AliExpress|
Mouser 603-MFR-25FBF52-2K7. Note R23, R24 are optional – cassette recorder support.
|Resistor||R25, R26||2.2 kohm, axial||2||AliExpress|
|Resistor||R27 – R33||1 kohm, axial||7||AliExpress|
Mouser 603-MFR-25FBF52-1K. Note R31, R32 are optional – cassette recorder support. Note R33 is optional – RGB output support.
|Resistor||R34||470 ohm, axial||1||AliExpress|
|Resistor||R35||180 ohm, axial||1||AliExpress|
Mouser 603-MFR-25FBF52-180R. Note R35 is optional – RGB output support.
|Resistor||R36||120 ohm, axial||1||AliExpress|
Mouser 603-MFR-25FBF52-120R. Note R36 is optional – RGB output support.
|Resistor||R37 – R42||100 ohm, axial||6||AliExpress|
Mouser 603-MFR-25FBF52-100R. Note R42 is optional – cassette recorder support.
|Resistor||R43 – R48||75 ohm, axial||6||AliExpress|
Mouser 603-MFR-25FBF52-75R. Note R46 – R48 are optional – RGB output support.
|Relay||RY1||5V SPDT relay||1||AliExpress|
Mouser 653-G5V-1-DC5 or Mouser 653-G5V-1-T90-DC5
|Inductor||L1||68 uH, axial||1||AliExpress|
|Inductor||L2, L3||5.6 uH, axial||2||AliExpress|
Mouser 512-1N4148TR. Note D1 is optional – cassette recorder support.
Mouser 512-PN2907ATF. Note Q1 is optional – cassette recorder support; Q2 is required for V9938 VDP only
Mouser 520-HCU443-20X. Note Y3 is optional – PAL support.
|Polyfuse||F1||750 mA, radial, 5 mm pitch||1||AliExpress|
|Connector||J1||DC Power Jack, 2mm||1||AliExpress|
|Connector||J2||RCA Phono connector, Yellow||1||AliExpress|
|Connector||J2||RCA Phono connector, White||1||AliExpress|
|Connector||J4||Mini DIN 4-pos, Right Angle, PCB mount||1||AliExpress|
|Connector||J5, J6||DIN 8-pos, Right Angle, PCB mount||2||This is a problematic connector. Depending on which PCB you get, you may need to purchase connectors from Mouser or AliExpress. Check the PCB before you buy it.|
Mouser 490-SDF-80J. Note J5 is optional – RGB support; J6 is optional – cassette recorder support.
|Connector||J7, J8||Sub-D DE9M, Right Angle, PCB mount||2||AliExpress|
|Connector||J9||Micro Ribbon 14-pos, Female, Right Angle, PCB mount||1||AliExpress|
Mouser 636-112-014-213R001. Note J9 is optional – printer port support.
|Connector||J10||8 pin friction lock connector||1|
|Connector||J11||2×8 pin header, shrouded||1||AliExpress|
|Connector||J12||2×20 pin socket||1||AliExpress|
|Connector||J13||2×2 pin header||1||AliExpress|
Note: Optional /RESET and /NMI header
|Connector||J14||1×13 pin header||1||AliExpress|
Note: Optional Color Bus header
|Connector||SLOT1, SLOT2||50 pin card edge connector||2||AliExpress|
|Battery Holder||BT1||CR2032 Battery holder||1||AliExpress|
|Battery||BT1||CR2032 Battery||1||You can purchase from your local convenience store.|
|IC Socket||U1, U2, U4||40 pin DIP||3||AliExpress|
|IC Socket||U3||64 pin DIP||1||AliExpress|
|IC Socket||U6, U7||32 pin DIP||2||AliExpress|
|IC Socket||U47||24 pin DIP, 400 mil spacing||1||Mouser 517-4824-6000-CP or 517-4824-3000-CP. Note: Cut the socket in the middle. If using a socket with 600 mil spacing, remove excess material. Alternatively, solder U47 (CXA1645P) without using a socket.|
|IC Socket||U12 – U14, U19 – U26||20 pin DIP||11||AliExpress|
|IC Socket||U5, U8 – U11||18 pin DIP||5||AliExpress|
|IC Socket||U15 – U18, U27 – U32, U46||16 pin DIP||11||AliExpress|
|IC Socket||U33 – U45||14 pin DIP||13||AliExpress|
|IC Socket||U48, U49||8 pin DIP||2||AliExpress|