MIDIbox SID-NUXX - Mainboard

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Three MIDIbox SID-NUXX Mainboards


The MIDIbox SID-NUXX's mainboard is six of the MIDIbox Hardware Platform modules and a simple dual-voltage power supply all fit on to one PCB. The PCB is also designed to fit cleanly into the grooves in the side of a Hammond 1455T1601-series enclosure. One side of the PCB also provides connectors for power input, audio in/out, MIDI in/out/thru, and a power switch.

The six modules implemented on the MIDIbox SID-NUXX mainboard are the Core, DINX1, BankStick, LTC, SID, and IIC MIDI modules.


These modules allow for a single PCB which uses a SID for audio filtering and generation. Other features include:

  • Power, MIDI In, and MIDI Out LED connections.
  • Support for up to eight switches (pushbuttons, rotary encoders, etc).
  • Header to alow more input modules to be connected, supporting more switches.
  • Storage of 128 or 256 patches. (In order to store 256 patches, a Microchip 24LC512 must be for IC6. This part is denoted as IC6 alternate.)
  • Display connector to allow for easier selection of patches, programming of synthesis parameters, etc.
  • MIDI output handled by IIC MIDI module to work around bug in PICs currently used in the Microchip PIC18F4620. This workaround allows the newer PIC to be used in the core module. (Note that per a Microchip errata document silicon versions B4 and higher will not have this bug.)
  • Header to allow addition of memory (BankStick) modules.

Additionally, the MIDIbox SID-NUXX has some design features which I don't believe are found on other MIDIbox implementations:

  • All audio in and out lines run isolated, not crossing any on-board signal nor power lines.
  • Audio in jack shorts input line to ground when a 1/4" plug is not inserted, helping to eliminate noise which could be picked up and fed into the SID.
  • Per MOS SID 6581 specification, Vcc, Vdd, and GND lines are run to the power supply separately. I do not believe this makes much of a difference on such a small board, but as it was in the specification, it was done.
  • ICSP (In-circuit Serial Programming) header to allow reprogramming of Core PIC, should it be needed.

MIDIbox SID-NUXX Mainboard PCB v1.1 in CADsoft EAGLE (More...)


The PCB was designed by me based on the aforementioned MIDIbox Hardware Platform Reference Designs in CADsoft EAGLE. While I had previously made the original CAD files and photoplotter files available, I have chosen to no longer make them publicly available.

The schematic can also be viewed as a 300dpi PNG export or a printer-ready letter-sized PDF.

A 300dpi export of the PCB layout (minus the upper ground plane for clarity) is also available.


To start, I do not have any of these PCBs for sale. For a vareity of reasons I am not making them available, nor am I allowing them to be a sold in a commercial capacity. However, if you would like to have some of these PCBs made for youself (and maybe a few close friends), feel free. Just don't sell them.

In order to have PCBs manufactured one generally needs to send photo plotter and drill files to a manufacturing facility. To create these files one must render them from their PCB CAD software. In my case I used EAGLE's CAM tool to generate the required files.

These files are ready to be uploaded to a company such as PCBFABEXPRESS or Advanced Circuits for manufacturing. They also have been confirmed to pass Advanced Circuit's FreeDFM checks. The plotted output from these checks in PDF format can be viewed here.

Pinouts / Header Information


ICSP (In-circuit Serial Programming). Connected to IC10 (Core PIC – PIC18F4620) so that it may be reprogrammed without removal from board. Pin compatible with Microchip’s PICkit 2.

Vp: Vpp/MCLR
Vd: Vdd Target
Vs: Vss (Ground)
PD: ICSPDAT/PGD (Programming Data)
PC: ICSPCLK/PGC (Programming Clock)
NC: Auxiliary / Not Connected (Not Needed)


DINX4 Inputs. Each labeled pin D0-D7 provides one digital input. VS is Vss, the common pins which D0-D7 connect with to signal an input.


LED Connection. Hardware power, MIDI Input, MIDI Output LEDs. Does not rely on MIOS being loaded in order to function. Replace R12, R13, and R14 to vary the brightness of the LEDs if the default is not acceptable.

PW: Power LED
IN: MIDI Data In
OU: MIDI Data Out
+5V: 5VDC for LEDs. Anodes connect here.


BankStick Connection. Essentially the equivalent of J4 in MBHP_CORE. Know that if more BankSticks are connected, addressing of new BankSticks should begin with 1.

Vd: Vdd
SD: Serial Data
SC: Serial Clock
Vs: Vss


J8 half of connector is equivalent of J8 in MBHP_CORE. J9A is essentially the equivalent of J9 in MBHP_CORE, except it has already been connected and passed through a DINX1. Therefore, SI of J9A connects to SER (Pin 10) of IC8 (the 74HC165) in the DINX1 instead of directly to RD1 (Pin 20) of the Core PIC as it would in the reference design. (See schematic for more information.)


Display Connection. Equivalent of J15 in MBHP_CORE.


All prices are in US dollars and were calculated on 03-Aug-2006.

From Mouser: All parts except for the alternate TO-220 heatsinks and alternate IC6 (24LC512), with minimum quantities for resistors fulfilled: $51.68

From Jameco: Wall-Mount Transformer: $4.89

From PCBFABEXPRESS: Single PCB: $13 (Minimum Order is Five Pieces)

Shipping: ~$13 (~$5 from Mouser, ~$5 from Jameco, $3 per board from PCBFABEXPRESS)

Parts to assemble a Mainboard

Bill of Materials


  • Almost all parts are required in the quantity detailed, except for those labeled alternate. Read on for information as to when these parts are needed.
  • Some parts (such as resistors) may have minimum orders greater than the required quantity. Fortunately this minimum is typically ten (10) pieces, which does not add significant cost to the project.
  • If using a MOS 6581 SID, be certain to use an LM7812 for IC9 and 470pF caps for C2 and C3.
  • If using a MOS 8580 SID, be certain to use an LM7809 for IC9 and 6.8nF caps for C2 and C3. (These parts are designated alternate in the Component List.)
  • The 532-579302B00 heatsink from Mouser is for TO-220 parts (such as the LM78xx series) with beveled sides. This is the correct part to use with the voltage regulators specified in the BOM. An alternative part, the 532-579402B00, is available for TO-220 packages with straight sides. If you use voltage regulators other than those specified, be sure to order the correct heatsink for your regulators. Aavid's published mechanical specifications for the heatsinks on the BOM can be used to help determine which parts you need. Or, just order two of each part and see which fits best. Be careful, using the wrong heatsink will cause a poor fit and improper cooling of the regulators.
  • The 16PJ031 power jack has a 2.1mm center pin, while the 16PJ032 has a 2.5mm center pin. Be certain to order the appropriate part to mate with your power supply. The listed power supply from Jameco (309884 has a 2.1mm center pin, and thusly the standard part for PWR1 (16PJ031) should be used with this supply.
  • Individuals outside of areas which use Type A / NEMA 1-15 power outlets will have to select a different power supply which is appropriate to their area. It should output ~12VAC or ~15VDC and have an appropriately sized barrel connector.
  • R12-R14 values may vary depending on the LEDs used for Power, MIDI In, and MIDI Out. Calcuation and / or experimentation with the chosen LEDs will allow one to establish a proper value.
  • For IC6, a 24LC256 should be used if one bank of patches (128 patches total) are desired. If two banks of patches (256 patches total) the alternate part 24LC512 should be selected.


The MIDIbox SID-NUXX's mainboard is a custom designed 159mm x 80mm PCB. I designed this implementation in late June and July 2006. The first run of boards, v1.0 S1, was manufactured by PCBFABEXPRESS in a quantity of five pieces for my personal use. Changes from these boards have been implemented in the the aforementioned v1.1 design.

Components on PCB

Part Name on PCB Value Part Number Quantity Photo Catalog Description
AUDIO_IN, AUDIO_OUT   568-NYS216 2   Neutrik Phone Jacks 1/4" STEREO SWITCHED
C1, C4, C8, C12, C14, C15, C18-C21, C26, C30 100nF 80-C412C104K5R 12   Kemet Conformally Coated Axial Ceramic Capacitors 50V X7R .1uF 10%
C2, C3 470pF 23PS147 2   Xicon Polystyrene Film Capacitors STRENE 50V 470PF
C2, C3 (alternate) 6.8nF 23PS268 2   Xicon Polystyrene Film Capacitors STYRENE 50V .0068uF
C5 1uF 140-HTRL50V1.0-RC 1   Xicon Hi-Temp Radial Electrolytic Capacitors 50V 1.0uF 105C
C6, C13 1nF 80-C410C102K5R 2   Kemet Conformally Coated Axial Ceramic Capacitors 50V X7R 1000pF 10%
C7, C10, C11, C25, C29 10uF 140-HTRL25V10 5   Xicon Hi-Temp Radial Electrolytic Capacitors 25V 10uF 105C
C9 470pF 581-SA101A471JAR 1   AVX Axial Ceramic Capacitors 100V 470pF NPO 5%
C16, C17 15pF 81-RPE5C1H150J2P1Z03 2   Murata Monolithic Radial Lead Capacitors 15pF, 50volts, C0G
C22, C27 33pF 81-RPE5C1H330J2P1Z03 2   Murata Monolithic Radial Lead Capacitors .1LS 33PF 50V 5%
C23 2200uF 140-HTRL25V2200-RC 1   Xicon Hi-Temp Radial Electrolytic Capacitors 25V 2200uF 105C
C24, C28 330nF 581-SR215E334MAR 2   AVX Radial Monolithic Capacitors 50V .33UF Z5U 20%
D1 1N4148 512-1N4148 1   Fairchild Diodes - Small Signal DO-35 100V Io/200mA
D2-D5 1N4004 512-1N4004 4   Fairchild Rectifiers DO-41 Vr/400V Io/1A T/R
IC1 6N138 512-6N138 1   Fairchild Optocouplers DIP-8 DIP-8 HG PHOTO DARL
IC2 MOS 6581   1    
IC2 (alternate) MOS 8580   1    
IC3, IC4 74HC595 512-MM74HC595N 2   Fairchild High Speed CMOS HC/HCT Logic DIP-16 8-Bit Shift Register
IC5 74HC00 512-MM74HC00N 1   Fairchild High Speed CMOS HC/HCT Logic DIP-14 Qd 2-Input NAND Gate
IC6 24LC256 579-24LC256-I/P 1   Microchip Serial EEPROM - 256k PDIP-8 32kx8 - 2.5V
IC6 (alternate) 24LC512 579-24LC512-I/P 1   Microchip Serial EEPROM - 512k 64kx8 - 2.5V
IC7 PIC16F88-I/P 579-PIC16F88-I/P 1   Microchip PICmicro - PIC16Fxxx Flash MCU's PDIP-18 7KB 368 RAM 16 I/O
IC8 74HC165 512-MM74HC165N 1   Fairchild High Speed CMOS HC/HCT Logic DIP-16 8-Bit Shift Register
IC9 LM7812 511-L7812ACV 1   ST Voltage Regulators TO-220AB 12V 1.0A Positive
IC9 (alternate) LM7809 511-L7809ACV 1   ST Voltage Regulators TO-220AB 9.0V 1.0A Positive
IC10 PIC18F4620-I/P 579-PIC18F4620-I/P 1   Microchip PICmicro - PIC18Fxxx Flash MCU's PDIP-40 64KB 3804 RAM 36 I/O
IC11 LM7805 511-L7805ACV 1   ST Voltage Regulators TO-220AB 5.0V 1.0A Positive
IC1, IC6 Socket 575-193308 2   Mill-Max DIP Low Profile Sockets 8P TIN PIN GOLD CONT
IC2 Socket 575-193628 1   Mill-Max DIP Low Profile Sockets 28P TIN PIN GLD CONT
IC3, IC4, IC8 Socket 575-193316 3   Mill-Max DIP Low Profile Sockets 16P TIN PIN GLD CONT
IC5 Socket 575-193314 1   Mill-Max DIP Low Profile Sockets 14P TIN PIN GLD CONT
IC7 Socket 575-193318 1   Mill-Max DIP Low Profile Sockets 18P TIN PIN GLD CONT
IC10 Socket 575-193640 1   Mill-Max DIP Low Profile Sockets 40P TIN PIN GLD CONT
J1   571-1032396 1   AMP AMPMODU Breakaway Headers 6 P HEADER GOLD 30u, single row
J2, J9A/J8   571-1032405 2   AMP AMPMODU Breakaway Headers 10P HEADER GOLD 30u, double row
J3   571-1032403 1   AMP AMPMODU Breakaway Headers 6P HEADER GOLD 30u, double row
J4A   571-1032394 1   AMP AMPMODU Breakaway Headers 4 P HEADER GOLD 30u, single row
J15   571-1032408 1   AMP AMPMODU Breakaway Headers 16P HEADER GOLD 30u, double row
MIDI_IN, MIDI_OUT, MIDI_THRU   161-0504 3   Kobiconn DIN Jacks 5 PIN DIN PCB
PWR1   16PJ031 1   Kobiconn DC Power Jacks PCB 2.1mm
PWR1 (alternate)   16PJ032 1   Kobiconn DC Power Jacks PCB 2.5mm
R1, R2, R8, R10, R11 220Ω 291-220-RC 5   Xicon 1/4W 5% Carbon Film Resistors 220ohms 0.05 (Red - Red - Brown)
R3, R17, R20-R26, R28-R30, R32, R33 10KΩ 291-10K-RC 14   Xicon 1/4W 5% Carbon Film Resistors 10Kohms 0.05 (Brown - Black - Orange)
R4, R18, R19, R31, R34 1KΩ 291-1K-RC 5   Xicon 1/4W 5% Carbon Film Resistors 1Kohms 0.05 (Brown - Black - Red)
R5, R9 10KΩ 531-PT6KV-10K 2   Piher Trimmer Potentiometers 10Kohms 6mm Rnd Top adj
R6 1.2KΩ 291-1.2K-RC 1   Xicon 1/4W 5% Carbon Film Resistors 1.2Kohms 0.05 (Brown - Red - Red)
R7 5.6KΩ 291-5.6K-RC 1   Xicon 1/4W 5% Carbon Film Resistors 5.6Kohms 0.05 (Green - Blue - Red)
R15, R16 100KΩ 291-100K-RC 2   Xicon 1/4W 5% Carbon Film Resistors 100Kohms 0.05 (Brown - Black - Yellow)
R12-R14, R27 470Ω 291-470-RC 1   Xicon 1/4W 5% Carbon Film Resistors 470ohms 0.05 (Yellow - Violet - Brown)
SW1   108-1MS1T2B4M7QE-EVX 1   Mountain Switch Miniature Toggle Switches SWITCH TOGGLE SPDT
T1 BC337 512-BC337 1   Fairchild Small Signal Transistors TO-92 NPN 45V 800mA HFE/63
T2 BC547 625-BC547A 1   Vishay Semiconductors Small Signal Transistors TO-92 NPN 45V 100mA HFE/220
XTAL1 20MHz 73-XT49S2000-20 1   Vishay/Dale HC-49/S Microprocessor Crystals 20.0 MHZ 20pF
XTAL2 10MHz 73-XT49S1000-20 1   Vishay/Dale HC-49/S Microprocessor Crystals 10.0 MHZ 20pF

Other Components

Part Part Number Quantity Photo Catalog Description
TO-220 Heatsink 532-579302B00 2   Aavid Thermalloy Heatsink TO-220 HORIZ/VERT SNAP DOWN 16.8 TR
TO-220 Heatsink (alternate) 532-579402B00 2   Aavid Thermalloy Heatsink BLACK ANODIZE TO-220
Wall-Mount Transformer 309884 1   TRANS,WALL,12VAC/1A,2.1X5.5MM,F,UL/CUL

Mouser BOM Import Tool

This list can be copy and pasted into Mouser's BOM Import Tool (requires a My Mouser account) to facilitate easy ordering of all required parts. This list does not include a SID, alternate TO-220 heatsinks, alternate IC6 (24LC512), wall-mount transformer, or PCB:

568-NYS216 2
80-C412C104K5R 12
23PS147 2
23PS268 2
140-HTRL50V1.0-RC 1
80-C410C102K5R 2
140-HTRL25V10 5
581-SA101A471JAR 1
81-RPE5C1H150J2P1Z03 2
81-RPE5C1H330J2P1Z03 2
140-HTRL25V2200-RC 1
581-SR215E334MAR 2
512-1N4148 1
512-1N4004 4
532-579302B00 2
512-6N138 1
512-MM74HC595N 2
512-MM74HC00N 1
579-24LC256-I/P 1
579-PIC16F88-I/P 1
512-MM74HC165N 1
511-L7812ACV 1
511-L7809ACV 1
579-PIC18F4620-I/P 1
511-L7805ACV 1
575-193308 2
575-193628 1
575-193316 3
575-193314 1
575-193318 1
575-193640 1
571-1032396 1
571-1032405 2
571-1032403 1
571-1032394 1
571-1032408 1
161-0504 3
16PJ031 1
16PJ032 1
291-220-RC 5
291-10K-RC 14
291-1K-RC 5
531-PT6KV-10K 2
291-1.2K-RC 1
291-5.6K-RC 1
291-100-RC 3
291-100K-RC 2
291-470-RC 1
108-1MS1T2B4M7QE-EVX 1
512-BC337 1
625-BC547A 1
73-XT49S2000-20 1
73-XT49S1000-20 1


The current revision of the mainboard PCB is 1.1. Changes from v1.0 S1 (set 1) to the current v1.1 are as follows:

  • Indicator / part outline for D1 (1N4148 as part of MIDI IN) was reversed in v1.0 S1. This has been corrected.
  • Pin TN on AUDIO_IN has been connected to ground. This helps eliminate excess noise from entering the SID when an audio input is not connected.
  • Slight rearrangement / clarification of trace routing in center of PCB, near version tag.
  • General readability improvements in the schematic.
  • Note regarding variability of values for R12-R14 added to schematic.