MIDI Retrofit & Decoder Kits, DIY Electronics—Worldwide Delivery
MPA: Assembly Notes
Important Information
- Mount components correctly. This kit contains an electrolytic capacitor, part C7. If parts C7 or D2 are installed backwards, C7 could explode during operation. The voltage regulator, part IC3, can become extremely hot if installed backwards.
- Do not exceed the specified electrical limits of the device. Placing too great a load on the MPA's outputs or exceeding the specified supply voltage can cause excessive heating and could damage the device.
- Do not apply external voltages to the MPA's 5V output, Digital Logic Outputs, or MIDI THRU ports. This will cause excessive heating and will damage the MPA.
- This kit contains some ESD-sensitive parts. Please take reasonable static-control precautions when assembling the kit.
PCB Layout
The location of each part is clearly marked on the MPA circuit board.
MIDI Wiring
Wire pins 4 & 5 of the MIDI connector to the corresponding terminals of the MIDI In port. If installing a MIDI Thru connector, wire pins 2, 4, and 5 to the corresponding terminal of either MIDI Thru port.
To chain multiple MPA units together, MIDI connectors are not required—wire terminals 4 & 5 of either MIDI Thru port directly to the corresponding MIDI In terminals on the next MPA unit in the chain.
Parts List
All components are mounted on the side of the board with the white legend. Components can be mounted in any order, but it is easier to mount the smallest components first.
*Appearance of parts may vary.
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| Part | Image* | Notes |
|---|---|---|
| C1-C6 |  | None. |
| C7 |  | Positive end of capacitor has an indentation, and negative end is marked with arrow. Positive end must match the "+" symbol on the circuit board legend. |
| D1 |  | Dark band on diode must match the white band on the circuit board legend. |
| D2 |  | White band on diode must match the white band on the circuit board legend. |
| IC1 |  | Mount socket on circuit board first, then insert IC into socket. Notched end must match notch in the circuit board legend. |
| IC2 |  | Mount socket on circuit board first, then insert IC into socket. End marked with dot must match notch in the circuit board legend. |
| IC3 |  | Pin 1 is on the left in the photo. Pin 1 must match dot on the circuit board legend. Before mounting permanently, bend the leads so that the IC "leans" into the open space on the circuit board. |
| IC4 |  | Logic IC, 74HCT14. Mount socket on circuit board first, then insert IC into socket. Notched end must match notch in the circuit board legend. |
| IC5, IC6 | | Digital Potentiometer IC, MCP42xxx. Mount socket on circuit board first, then insert IC into socket. Notched end must match notch in the circuit board legend. |
| LED1, LED2 |  | The short lead must match the flat side on the circuit board legend. |
| R1, R2 |  | 1kΩ resistor, marked with the following color bands: brown, black, red, gold. |
| R3-R7 |  | 220Ω resistor, marked with the following color bands: red, red, brown, gold. |
| R8-R12 |  | 10kΩ resistor, marked with the following color bands: brown, black, orange, gold. |
| RN1 |  | Pin 1 (marked with a dot) must be inserted in the small box on the circuit board legend. |
| SW1 |  | Numbers on switch should match numbers on circuit board legend. |