7Dials CV Express User manual

Thank you for your purchase of the 7Dials CV Express module. We hope you nd this unit to be a creative
addition to your modular synthesiser.
This build guide will show you how to build the CV Express module, focusing on our kit for the popular
Eurorack format.
The assembly of this DIY module will only require a small amount of elementary electronics
knowledge, but (like any DIY project) it does require a good level of soldering ability. If you are yet to
acquire soldering skills or experience then we would recommend you rst practice on some simpler kits.
This project is not by any means a difcult build, but it wouldn’t really be considered an ideal starting
project for a total beginner.
There are some really good DIY learning resources and soldering tutorials available online,
for example:
Adafruit-Soldering-Guide
If you’re building the CV Express from one of our kits, please make sure you rst check the quantities and
component values of all parts against the BOM provided. All resistors of multiple quantities should have
their values noted on the tape. Single quantity resistors will need to be identied by the builder, we’ve
included a list of all the relevant resistor colour codes needed for this project. It’s certainly worth double
checking that the correct resistors are all going in the right spots.
100k - Brown-Black-Black-Orange--Brown
110k - Brown-Brown-Black-Orange--Brown
1k - Brown-Black-Black-Brown--Brown
390r - Orange-White-Black-Black--Brown
36k - Orange-Blue-Black-Red--Brown
4k7 - Yellow-Violet-Black-Brown--Brown
2k - Red-Black-Black-Brown--Brown
4m7 - Yellow-Violet-Black-Yellow--Brown
100r - Brown-Black-Black-Black--Brown
10k - Brown-Black-Black-Red--Brown
200k - Red-Black-Black-Orange--Brown
220k - Red-Red-Black-Orange--Brown
220r - Red-Red-Black-Black--Brown
If you’re not building from a kit please refer to the BOM where we list part numbers and provide links to
various suppliers. All of the links are provided only as an aid to help the diy builder nd or compare the ap-
propriate part required for this project.
Any links provided in this manual are not to be seen as an endorsement of that product.
If you are sourcing your own parts and have any questions, please don’t hesitate to contact us, we’ll be
happy to help in any way we can. Builders can also check out the dedicated 7Dials CV Express Muffs
thread:
https://www.muffwiggler.com/forum/viewtopic.php?t=145913&start=0
CV Express build guide version 1.0
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Build order
Prior to installing the resistors you rst need to check and conrm the values, either visually, using the
provided colour codes, or by measuring with a multimeter.
CV Express build guide version 1.0
1.
Locate and install the single 390r resistor in the place marked R29.
390r resistors are marked - Orange-White-Black-Black--Brown
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CV Express build guide version 1.0
2.
Next, Install the single 36k resistor in the place marked R4.
36k resistors are marked - Orange-Blue-Black-Red--Brown
3.
Next, Install the single 4.7m resistor in the place marked R9.
4m7 resistors are marked - Yellow-Violet-Black-Yellow--Brown
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CV Express build guide version 1.0
4.
Next, Install the single 100r resistor in the place marked R10.
100r resistors are marked - Brown-Black-Black-Black--Brown
5.
Next, Install the single 220k resistor in the place marked R21.
220k resistors are marked - Red-Red-Black-Orange--Brown
** Double check you don’t mix up the 220k and 220r resistors **
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CV Express build guide version 1.0
6.
Next, Install the single 220r resistor in the place marked R31.
220r resistors are marked - Red-Red-Black-Black--Brown
7.
Next, Install the pair of 4.7k resistors in the places marked R6 & R11.
4k7 resistors are marked - Yellow-Violet-Black-Brown--Brown
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CV Express build guide version 1.0
8.
Next, Install three 10k resistors in the places marked on the Front Panel Component PCB as R13, R23 &
R30.
10k resistors are marked - Brown-Black-Black-Red--Brown
9.
Next, Install four 2k resistors in the places marked on the Front Panel Component PCB as R7, R17, R25
& R34.
2k resistors are marked - Red-Black-Black-Brown--Brown
** Double check you don’t mix up the 2k and 200k resistors **
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CV Express build guide version 1.0
10.
Next, Install four 200k resistors in the places marked R18, R22, R28 & R39.
200k resistors are marked - Red-Black-Black-Orange--Brown
11.
Next, Install the pair of 110k resistors in the places marked R15 & R40.
110k resistors are marked - Brown-Brown-Black-Orange--Brown
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CV Express build guide version 1.0
12.
Next, Install the ve 1k resistors in the places marked R3, R8, R20, R27 & R38.
1k resistors are marked - Brown-Black-Black-Brown--Brown
13.
Next, Install the fourteen 100k resistors in the places marked R1, R2, R5, R12, R14, R16, R19, R24, R26,
R33, R35, R36, R37 & R41.
100k resistors are marked - Brown-Black-Black-Orange--Brown
13.
Now move onto soldering the diodes. There are a few different types included in the CV Express kit and
it’s very important that they are all put in the right places and also that they are all orientated correctly.
It’s also important not to linger too long with the soldering iron when installing diodes, they can easily be
damaged by excessive exposure to heat.
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CV Express build guide version 1.0
14.
Install the pair of 1n4148 diodes in the places on the pcb marked D1 & D2. (2x loose in cap bag, small red
body/black band on one end)
Please refer to the picture, it’s very important that the black band is orientated correctly with the white
stripe silkscreen marking on the pcb.
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CV Express build guide version 1.0
15.
Next, Install the pair of 1n4001 diodes in the places marked D4 & D5 (2x in cap bag, large black body/
silver band on one end)
Please refer to the picture, it’s very important that the silver band is orientated correctly with the white
stripe silkscreen marking on the pcb.
Next we proceed with installing the caps.
All of the ceramics caps are bipolar, so orientation is not important, but the two tall black 10uF electrolytic
caps are polarised, so it’s important to ensure that the instructions are closely observed when installing
that pair.
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CV Express build guide version 1.0 CV Express build guide version 1.0 CV Express build guide version 1.0
16.
Install the four 100nF ceramic capacitors in the places marked C1, C4, C6 & C7.
(4x loose in cap bag, small orange body, long legs), be aware three of them are installed under, or on the
opposite side of the TL074’s. As long as you ensure the correct value is installed the side of the board the
caps are installed on doesn’t really matter. I personally prefer to install them on the same side as all of the
other passive components. This does mean that the ic sockets cover them, but they are still able to be
removed if required when installed this way.
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CV Express build guide version 1.0
17.
Next, Install the single 10nF ceramic capacitor into the place on the pcb marked C2.
(1x loose in cap bag, small orange body, marked cardboard tape)
18.
Next, Install the three 3.3pF ceramic capacitors in the places marked C8, C9, C10.
(3x loose in cap bag, small blue body)
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CV Express build guide version 1.0
19.
Next, Install the three 14 pin ic sockets, ensuring the notch in the socket is aligned with the silkscreen
image on the pcb, all of the sockets point upwards.
20.
Next, Install the two PTC fuses, these go in the two places marked 0.1a just above the power header,
orientation does not matter.
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21.
Next, Install the LM317LZ in the space marked U4, make sure to orientate it so it matches the silkscreen
image.
22.
Next, Install the 2x5 way power header.
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23.
Next, Install the 2k trimmer.
24.
Next, Install the 2x 10uf electrolytic caps in the spaces marked C3 and C5. It’s very important that these
capacitors are installed correctly. The long leg goes into the square hole which has an associated + sym-
bol next to it, the shorter leg goes into the round hole, so the gray stripe on the body of the cap is orien-
tated away from the edge with the blue trimmer.
Please check the photo to conrm correct orientation.
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25.
Next, install the male pin headers, these are installed on the opposite side of the PCB of all of the
components that have been installed so far.
Please note: the 3pin header location marked J23 is left empty, do not install anything there.
No harm will come if you do, you’ll just need another 3 pin male strip to continue with the build if building
from the kit.
CV Express build guide version 1.0
Look to get all the headers aligned neatly and ush with the pcb. Some people prefer to put the pcb
sandwich together and then tack solder 1 pin of all the male headers rst, and then (after conrming
everything is aligned) go back and solder all of the remaining pins. The female pin headers on the front
panel component pcb are not installed until later in the build, so don’t solder any of them in just yet.
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26.
Next, Install the six Thonkiconn jacks to the front panel component pcb.
Fit the jacks to the pcb, then place the panel, and nger tighten some of the jack nuts to couple the panel
to the jacks and conrm the jacks are all installed cleanly, ip it over and then solder.
27.
Next, Install the TL074 into the 14 pin ic socket on the front panel component pcb.
It’s not imperative to install it now, and some may prefer to do after all the soldering is complete. Just bear
in mind that it’s rather difcult to install an ic once all the pots and switches are installed.
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28.
Next, Install (but don’t solder yet) the remaining front panel components, consisting of ve B100k 9mm
pots, the SPDT switch, three red/green bipolar led’s and a single orange led.
For the orange led, the short leg (cathode) is closest to the edge of the board - the at edge of the
silkscreen outline.
The orange led is installed into the placed marked D3.
For the BiLED’s, the inner circle indicates the cathode of the primary led, so the short lead goes through
the inner circled hole on the silkscreen (this presumes the builder wants red to indicate positive voltages
and green to indicate negative voltages).
All BiLED cathode points are located nearer the outside edge of the pcb as per the pcb silkscreen, so
please note:
** BiLED2 faces the other way from BiLED1 and BiLED3 **
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Finger tighten onto the front panel some of the nuts for the pots, jacks, and the switch. This helps align the
parts to the panel.
Flip the panel and ensure that all four led’s are protruding correctly through their panel holes, then you can
nally start to solder the pots, switch and led’s.
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29.
Next, Install the female headers on the front panel component pcb.
These headers are installed on the opposite side of the front panel component pcb of any components
installed prior to this step.
It’s worth considering attaching the other pcb and aligning all the headers before tack soldering a single
pin on all headers, and then proceeding to solder the rest of the pins once it’s conrmed everything is
lined up correctly.
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