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In the beginning of this year I decided I was going to finally build The Sequencer.

I built my first MIDIbox project 4 years ago, a stereo MB SID, and have been hooked since.

Next to my kids, this is the greatest thing in my life, I love it.


There's so many great tutorials and tips on the forum about building the SEQ V4, so there's not really a need for another one, but I thought I'd share a few 

things I did in my build.



I used the STM32F4 based Core, with the now available PCB.

To save some space in the case, I moved and removed some parts.
Removed the jack and the button caps. Cut the buttons and some pins. Moved some pins to the underside.


I used the Kyocera LCD's, and read a tip by Altitude about the back light.
I omitted the transistor and the resistors, put in a bridge and a multiturn trim pot.
Like sometimes at Mouser, the part doesn't look like the picture, but it sort of fits ;)


I wanted the max MIDI OUT's, so I used 2xMIDI I/O and 2xQuad IIC boards for 12 OUT and 4 IN
The PICs on the second Quad IIC board needs a modified firmware.
Tim AKA "Not Mike" AKA SmashTV has it now, but if you want to burn it yourself, it's downloadable further down.
The rest of the build is pretty standard.
Wilba PCB, Schaeffer front panel and common parts.
The case is laser cut acrylic done locally.
With the mods on the Core, it's only 4 cm. high :smile:


While I was at it, I built the BLM 16x4 and TPD as well
(FPD file further down)


The last piece was the tinted windows on the TPD, and they really look great I think
I am very happy with it, and it's so much fun to play.
Thank you TK for everything.
Thank you Wilba for the PCB ++
Thank you SmashTV for your shop and service ++
Thank you ilmenator for the BLM and TPD, and the "bling"
and of course thanks to the rest of you for all the help, support and inspiration.
Beers all around
edit: I thought I could buy you all beers, but it's only TK that has a working link
Wilbas redirects to a Rick Astley video :), and the others don't have one
oh well
Cheers Hal



Edited by eptheca
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NIce job, I'm just about to embark on the V4 build, so this is very timely, it's great to see it all come together for you.

I'm going for a more standard unit with 1 Midi I/O and 1 Quad IIc. I do have a BLM-TPD on the way though, so your build  certainly gives me ideas in that department.


and read a tip by Altitude about the back light.

can someone give me a link to this tip?



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thanks guys for the kind words :)



here's the link to Altitude's tip, 



-Core STM32F4

-MIDI I/O x 2, chained and connected to Core on J11E

-Quad IIC x 2, chained and connected to Core on J4A

-SEQ CS, connected to Core on J8/9

-BLM 16x4, connected to SEQ CS on J2

-TPD, connected to BLM on J1


I just finished it, so I have just scratched the surface on how to use it.

I now have 10 sound chip based synths/sound modules in my setup, and wanted direct MIDI connections for all of them.

The BLM gives me direct control of the 4 tracks in the group selected

With the TPD I can see and adjust the BPM, pluss its blinking and blinging ;)

I find out something new every time I use the SEQ V4, and with the rate of new features, I don't expect to ever totally master it


I have put in a lot of effort and money to make it look and feel as "pro" as possible, but the "amazing, awesome and outstanding" part is Thorsten's MB SEQ V4 firmware.

I have looked around, and can't find anything close to it. It's in it's own league.

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  • 2 months later...

Hi Guys,


Nice build eptheca!


I'm midway through a SEQV4 build with optrex displays myself and could use some help regarding the 5K trimmer backlight mod on the stm32f4 core board as I don't want to screw it up!


What would be the ideal part and method for the mod on this board?


remove bc337 & resistors, add bridge

remove P1 (LUMI) 10k trim pot,


Could we then mount this part where P1 was? http://nz.rs-online.com/web/p/trimmer-resistors/5219580/


Mfr. Part No. 3296P-1-502LF

Bourns 3296P Series 25-Turn Trimmer Resistor, 5kΩ ±10% 1/2W ±100ppm/°C


Also could I ask how the 2 lcds are connected from the J15A pin out in eptheca's pic? :huh: (confused)


Thanks for any help offered!

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Hi casius,


Yes that one will work, mine has a "weird" package

Do as you suggest:

>remove bc337 & resistors, add bridge

>remove P1 (LUMI) 10k trim pot,


I cut the third leg on the new trimmer, and mounted the two others to Ground and the bridge to B-

Before you connect the LCD's, measure the new trimmer, and set it to 2-3K so you can slowly increase the power 


The LCD's are connected in series with one flat-cable to J15B, because in my case I could use a shorter cable if it went to display 2 first.

I cut the wire from E after the connector to the closest display, and ran a separate wire to E from the other, to E on J15A.

Hope that explains it :)

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  • 5 months later...
  • 1 year later...

I have re-cased my SEQ in a Pelican-style plastic case.



Added a AOUT_NG with 8 CV and 8 Triggers

Connected MIDI OUT 1-8 to a DB9 D-Sub connector for easy connection to the other half of the case which will contain the synths.



Made a USB Micro cable with a switch to ground pin 4 for USB Host Support (OTG) as suggested by Yogi

Connected the cable to a female USB A socket so I can connect a MIDI keyboard or a GM5 for 4 more MIDI OUT (total of 16 direct outs)

With a USB A-A cable I can connect it to my computer for updates etc.

The extra USB socket is just 5V for a gooseneck light

Thought a case like this deserved a "Nuclear Football" key power switch :)


Edited by eptheca
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Hehe, cool!

For UTB OTG, I found a supply of Micro B cables terminated in a 100mil header:


-- you have to search to find different listings for each country... also on amazon etc.

The Disco board also has a breakout for OTG, instead of a custom cable a wire to a switch with 0V/ground on the other side will do. I'll have a new USB entry design ready for the alternative SEQ at some point.


Once again, cool work and I'm glad the MIDI thru drivers are working well.


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