Personal Circuits Midi-CV-8 User manual

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Midi-CV-8 v1.3 – Assembly Guide
Thank you for purchasing this module! This is a complicated build with tightly packed components
and precision integrated circuits. It is not recommended for the beginner.
The module is designed and sized for Eurorack systems. You will need a 16-pin eurorack power
ribbon connector with –12/0/+12 and +5V which is connected to a synth power supply.
Follow the parts lists, these instructions and the PCB silkscreen text to build the module.
The Midi-CV-8 consists of two PCB boards and a front panel.
There are components installed on BOTH sides of the boards. Please ensure that you place the
components on the correct side. When referring to the TOP of a board we mean the side with the
pmF logo. The BOTTOM has no logo.
You must follow the order of assembly as described below since some components will be soldered
underneath other components.

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Constructing the Gates board (labeled Midi-Seq-Gates)
1. Resistors
Install the flat resistors on the TOP of the board. Solder and clip the leads.
2. Jumpers
The TRS jack can be configured to operate as a DIN-TRS Type A jack (MIDI Standard) or as a Type
B jack. In a type A jack the Tip of the TRS acts as MIDI DIN pin 5 and the ring as MIDI DIN pin 4.
The type B jack is the opposite.
For a Type A jack install jumpers as follows:
5 - T
4 - R
For a Type B jack install jumpers as follows:
5 - R
4 - T
For type B, ensure the jumpers do not touch each other when they cross.

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3. Diodes
Install the diodes on the TOP of the board. These are polarized components. Align the stripe on
each diode with the stripe marked on the board. Solder and clip the leads.

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4. IC Sockets
Install the sockets on the TOP of the board. Observe the notch or mark on the socket and align
with the notch or mark on the board. Solder.
5. Power socket
Install the 16-pin power socket on the TOP of the board. The socket should face OUT from the
board. Solder.

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6. 5 pin male headers
These should be installed on the BOTTOM of the board and soldered on the TOP. Solder these
connectors at 90 DEGREES to the board as close as possible. The short part of each pin goes into
the board and the longer part sticks out from the board. It is very important that these items
are installed on the BOTTOM!
7. USB sockets
The B Type (Square) is installed first. This is installed on the BOTTOM of the board. After
soldering, cut all pins flush so they will not touch parts that will be installed after them.
Then install the A Type socket (Rectangular). This is installed on the TOP. Squeeze the frame
clips on each side together slightly so that it fits in the holes. Ensure that it is TIGHT and flush
against the PCB before soldering. Solder the pins and the retaining clips.

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8. LED
Install the LED on the BOTTOM. Cut the pins flush after soldering so they do not interfere with
parts that will be installed over them.

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9. Ceramic/film capacitors
Install the ceramic/film capacitors on the TOP of the board. Solder and clip the leads.
10. ICSP connector
Install the 6-pin ICSP connector on TOP. Orient so the long pins face out pins and the short pins
go into the board. See photos. Solder.
11. Electrolytic and tantalum capacitors
Install these on the TOP. Make sure you orient these capacitors correctly. The longer lead
and/or the lead marked with a + needs to be inserted into the hole that has the “+” marking
near it. Leads marked with “-“ go in the board hole WITHOUT the “+”. Solder and clip the leads.

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12. Voltage regulator
Install the Voltage regulator U4 on the TOP of the board. This is a polarized component. Align
the outline with the outline on the board. Solder and clip the leads.
13. 3.5mm Jack Sockets
Install the jacks on the top and the bottom. Solder each jack, one at a time ensuring that it is flat
against the board, upright, and aligned with the edge of the board. You can test the fit using the
front panel as a guide. The order for installing the jacks that will allow you to reach all the pins
is:
J7, J8, J1, J9, J2, J10, J11 (Three pins!). Now cut the pins of J11 flush with the board.
Continue installing the jacks and soldering as follows: J6 (This one is tricky!), J5, J4, J3.

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Constructing the CV board (labeled Midi-Seq-CV)
1. Resistors
Install the flat resistors on the TOP of the board. Solder and clip the leads.
2. IC Sockets
Install the IC sockets on the TOP of the board. Observe the notch or mark on the socket and
align with the notch or mark on the board. Solder.

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3. Female 5 pin connectors
These should be installed on the BOTTOM of the board and soldered on the TOP. Solder these
connectors at 90 DEGREES to the board as close as possible. It is very important that these items
are installed on the BOTTOM!
4. Ceramic/film capacitors
Install the ceramic/film capacitors on the TOP of the board. Solder and clip the leads.
5. Trimmer resistors
a. Use a multimeter to set these to approx 5k between pin 1 and 2. Use a trimmer
adjustment tool.

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b. Now populate the trimmer pots on the PCB.
6. 3.5mm Jack Sockets
Install the jacks on the top and solder.
Alignment
1. Join the two PCBs by aligning the 5 pin headers on the “Gates” board with the 5 pin female
headers on the CV board and press together carefully.

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2. Do not install the ICs until the voltage tests are complete.
3. If you do not trust all your soldering and connections, carry out the voltage tests below before
connecting an Android device or installing the ICs
Voltage tests
1. You do not have to do these tests if you are completely happy with your soldering and are sure
there are no bridges or incorrectly placed components. However, these tests will ensure that
the correct power supplies are sent to the IC pins to ensure they will not be damaged on power
up.
2. Plug in the power supply and connect the –VE probe of a multimeter set to the 20V range to
GND.
3. Check the voltage at the following points on the GATES board:
a. At IC4, IC5, IC6: pins 4,6,8,10 approx = 1.58V
b. At IC4, IC5, IC6 pins 5,7,9,11 = 0V
c. At IC4 and IC6: pins 1,2,3,13,14 approx = +5 V
d. At IC5: pins 12,13 approx = +10.5 V

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e. At IC5: pins 2 approx = 0 V
f. At IC5: pins 1 = +1.8 V
g. At IC4, IC5, IC6: pin 12 = 0V
h. At IC3 pin 16 Approx = +3.3V
i. At IC3 all other pins = 0V
j. At IC2 pins 1,13,23,25, 28 approx = 3.3V
k. At IC2 pins 8,15, 19,27 = 0V
l. At IC1: pins 1, 2, 3, 5, 7 = 0V, pin 8: = +5V, pin 6: = +3.3V
4. Check the voltage at the following points on the CV board:
a. At U1 pin2 approx = +12V
b. At U1 all other pins = 0V
c. At U2 and U3 pin 18 approx = +12 V
d. At U2 and U3 pin 15 = Anywhere from 0 to +5 V, but NOT +12V or -12V
e. At U2 and U3 pins 1,2,3,4,5,6 = 0V
f. At U4 and U5 pin 4 approx = +12V
g. At U4 and U5 pin 11 approx = -12V
5. If any of these tests fail to match the readings given, you should check the components and
soldering before progressing
6. TIP: If there are no shorts, missing components or unsoldered joints, the most likely cause for a
voltage discrepancy is one or more resistors in the wrong place. You will need to check the
value of each resistor against the BOM and the layouts shown in the photos of the unpopulated
boards.
Final Assembly
1. Place the ICs in place by aligning the notch with the notch graphic on the PCB Silk Screen and
notch on the sockets.
2. With the PCBs joined with the 5 pin connectors, place the front panel over the GATES and CV
boards so that the USB socket and 3.5mm jacks align with the holes in the panel.

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3. Put nuts on the jacks.
4. NOW READ THE USER GUIDE.