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midiphy Eurorack Expander Modules


latigid on
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Hi, the gates problem was indeed the midibox sending out an inverted signal. When changing in to positive it works also for the 2 other dout boards so i am confident that those are working good. So, 1 down of my problems.

My biggest concern is the AOUT board and especially the DAC board. First answering your questions:

* It is indeed -5v instead of +5v. Guess i am always thinking positive :)

* jumpered the board so it is now powered by the eurorack psu instead of USB

* I am using an official moog eurorack power cable, i have to mention something strange. When looking at Peters tutorial he i making the eurorack power cables like straight cables but when i compare them to an official eurorack psu cable they are all twisted. Difficult to explain but when i try to use the cables like Peter is making them i dont get any power. When i also twist them like a moog eurorack psu cable it is working perfectly. I really 100 times checked the video and i know it is exactly the same but no power. BTW this is only with the eurorack psu power cable but the module interconnect cables are working like how they are made in the video (confirmed by testing the gate/clock panels). 

* I think i screwed up with the DACs .. they were so tiny that i resolder them a couple of times. For all the boards i made i am 99% confident that the soldering is good. But with the DAC board i have a 20% good feeling and i think i killed the DACS. When the DACS are killed do i get the default -5v and what if only 1 is failing? Is there a good way to test the DAC board?

 


 

 

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Hi,

For IDC cables, the most important thing is that the red stripe or pin-1 marker is on the same side for both ends of the cable. It doesn't matter if the cables loop back around using the strain resistance or not, or in other words if the ribbon enters from the top or the bottom of the connector.

Shrouded headers on the bus boards will force the connection orientation though, so if the cables are "twisted" with the red stripe on different sides, the power polarity will be reversed. Maybe your power distribution has non-standard female headers? Pictures would help.

I don't think it's related to this though for the A1 module. Red lights on mean the op amps are correctly powered and with the -5V offset.

For the superDAC board, I hope that you didn't plug in the Eurorack power there? Pictures of the murder scene? Overheating is possible; what soldering temperature did you use? Having no output would be unexpected. I know that sometimes channels just become less linear. 

max525-5500.thumb.GIF.0e2e3cbbd96a043b2f

 

You should have +5V on the red pins, 2.048V on the blue pins. Yellow should be the DAC output. You should be able to measure this voltage or on the 11-pin header.

Check the cables as usual.

 

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3A7D7CB8-4C2C-43DA-8FED-AAE3345D0B0F.thu0CC1E1A1-399D-4F31-90AA-F98B80130877.thu0CC1E1A1-399D-4F31-90AA-F98B80130877.thuCD2BA838-CC80-478B-A1C1-4435C450BC95.thu

7F74E5C8-B432-4B34-AC03-47BD98986CAA.jpeg

 

Thanks for the feedback, will try to meassure things tonight but here are some pics of me doing some bad soldering on the dacs and pics of the cabling (only Gatesboard does not have euro power at the moment). 2 be continued ;-)

Edited by enveevee
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11 hours ago, latigid on said:

 

Quote

 

You should have +5V on the red pins, 2.048V on the blue pins. Yellow should be the DAC output. You should be able to measure this voltage or on the 11-pin header.

Check the cables as usual.

 

I can measure the +5v and 2.048v on the pins but don't know how to do this with the 11 pin header since I don't have the exact scheme for this pin layout. I tracked the traces to j19a header and can measure both the +5v and I was able to measure the 2.048v.

Quote

 

Use the MIOS terminal command "testaoutpin" and ensure that you can control each of SO SC RC1 (maybe SI but it isn't used for AOUT). The issue could be further up the line.

 

 

I am not exactly sure when I do example: testaoutpin sc 1 where to measure the pin sc .

Sorry I am a real noob when It comes to troubleshooting these things since I didn't study electronics :) 

 

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No worries!

For the cables, it is correct if the red stripe always ends up on the left of the notch. But always check the voltage: the red striped side should be -12V. 

 

The 11 pin header (J3) connects the superDAC board to the transmute8 board. The pin outputs are channels 1,2,3,4 0V NC 0V 5,6,7,8 (0V=ground, NC= no connection). Pin 1 is square shaped.

You can "calibrate" all channels to Max and see if you get any output.

If you're viewing the board from the top and with the J19 side up and the DACs showing, you have channel one closest to IC1 on the left of J3 and channel 8 on the right side.

 

For testing the pins, start with J19 on the Euroceiver with the IDC cable unplugged; i.e. measure from the topside of the J19 shrouded header. Once a cable is connected to superDAC, just use empty top pins of J19A. This will work at least for SC and RC1. You could also measure on the DAC pins but be careful not to slip with the probes.

J19.GIF.c785b2daf68377186a9eda82f2fd2afb

Edited by latigid on
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On IC2, pins 2,3,4,5, the pads look quite different, did something happen to them?

Also check that the pads make contact with the IC pins (power off). So test on the pad and the top of the IC pin just to make sure that there is a good connection. Test that no pads are shorted together, except for the channel outputs as indicated earlier.

 

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35 minutes ago, latigid on said:

 

Quote

You can "calibrate" all channels to Max and see if you get any output.

When I measure the pins I only get a value of 0.005v on pins 1234 and 5678

 

Quote

For testing the pins, start with J19 on the Euroceiver with the IDC cable unplugged; i.e. measure from the topside of the J19 shrouded header. Once a cable is connected to superDAC, just use empty top pins of J19A. This will work at least for SC and RC1. You could also measure on the DAC pins but be careful not to slip with the probes.

SO = 3.9v

SC = 3.9v

RC1 = 3.8v

 

Edited by enveevee
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16 minutes ago, latigid on said:

On IC2, pins 2,3,4,5, the pads look quite different, did something happen to them?

Also check that the pads make contact with the IC pins (power off). So test on the pad and the top of the IC pin just to make sure that there is a good connection. Test that no pads are shorted together, except for the channel outputs as indicated earlier.

 

Yes that is the screwup I did with some old desoldering braid and the pads where vanishing like clouds for the sun (Not a pcb issue but a total screwup from my side!) . I can't find any shorts for now but will reflow the pads one more time tomorrow to see if it helps. Without the J19 connected and CV board only connected by the eurocase power gives all lights red right away. I tested it also with the DAC board disconnected but again all lights red right away (don't know if this is a valid test :))). Tried different cables for power but all same result.

Edited by enveevee
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You're able to control the SO/SC/RC1 pins on and off? And they make it all the way to the superDAC board?

You can also measure on the DAC SI (Rx) and SO (Tx), pins 9 and 12, respectively. Even better if you have a scope, but the pins should show some voltage depending on the speed of your multimeter. Pin 7 should be at about +5V.

The previous troubleshooting was in another thread, but the -5V state and red LEDs are normal if the DAC channel doesn't deliver any voltage. In your case it seems like no channels are providing voltage.

Did you try the drag soldering method Peter suggested? Personally I prefer to use a chisel iron tip and just do a few pads at a time, then use desoldering braid to remove the shorts after.

 

 

 

 

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Hi, 

I did some testing and SO is going all the way to the DAC board to the J19A and tested with testaoutpin sc 0 and 1 

RC1 is going to the dac board all the way to j19a

SI has a really low voltage on the dac and I hope that I measured it right but I get a 5v on pin 12 SO

I first tried soldering your way since that is my way with chips like the opamps and they are very clean and reliable . With the dacs I got some joined legs and tried to remove it with the soldering braid but that killed 3 or 4 pads and hard to see if they are still there but I get no voltage whatsoever from 16 / 17 / 18 / 19 on the dacs so I think my dacs or pcb is /dev/null . After killing some pads I tried to do some drag soldering with a seagull tip and that worked pretty good but it was to late to clean up the massacre I did. :(

Maybe ordering a new pcb and some new dacs and things from mouser is the next step.

New update : I desoldered the dacs but the pcb and dacs are too much damaged. It was funny because when I powered it on I some some different colour leds but the psu was making some very slight noise and then they went red again. However it was a sign that the problem is around the dacs I guess. Don't wanna kill my psu so I shut the thing off and the pcb and dacs are going to /dev/null :(

For now thanks for all your help!

Cheers Niels

 

 

 

Edited by enveevee
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5 hours ago, latigid on said:

Hi Niels,

Thanks for the update and details. I'm sorry that you had trouble with the soldering but maybe something was learned along the way. On the upside, the PCB can be easily replaced and because it's modular you don't have to throw away the rest :).

Best,
Andy

I am not really experienced with the really tiny soldering like the dacs but experience comes with trial and error and it will probably work out this time, You can't always throw six :) 2 be continued

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Just now, latigid on said:

@TK. looks awesome and I'm glad it fits! Will you fill the rest with more CV modules or get a nice filter or VCO? :)

@enveevee don't worry, we'll send some replacement boards and you can try again :).

It would also be nice to do some lfo's from the midibox to a eurorack panel .. i am a sucker for lfo's 

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A downstripped MBHP_CORE_STM32F4 module in Eurorack format would be nice-to-have as an alternative solution to the Euroreceiver - maybe with a SCS (6 buttons, encoder, display) - this would allow to run MBCV which gives us a lot of LFOs, Envelopes, sequencers, modulation matrices, etc.

Best Regards, Thorsten. 

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46 minutes ago, TK. said:

A downstripped MBHP_CORE_STM32F4 module in Eurorack format

I'm working on something like this, I try to do not exceed 50mm depth. I need it for the HAARP,
1905_mb-haarp_euro_v1b_core_02.png?raw=1

And adapt the SCS to the euro format is also a good idea, @latigid on ?

I plan to create another CS based on the work I made for @Phatline with a pot for each parameter and TFT screen, like I did for the HAARP.

Best regards,
Bruno

 

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The wCore currently available could also be used as an F4 Core variant mounted in a Eurorack system. Depth would be the PCB length, so 77.5mm. The idea was to USB/SD PCBs mounted on the front panel, plus any MIDI DIN etc. as needed.

I think the next ProgrammA iteration would be a fine controller for MBCV and would use the same Line Driver/Euroceiver combo :).

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Sure, most skiff cases are much shallower than this. I built my own cases with probably >100mm depth, because a lot of the DIY modules from years ago were much deeper :).

wCore has all of the expected ports and could be mounted "straight on" like is done for the SEQ. This would have a shallower depth but a wider panel of course. It's a compromise of using pre-fabbed MCU breakouts and avoiding fine-pitch SMT, as it can be difficult sometimes as we've seen!

You could also panel-mount a Discovery board Core in the same way. You'd miss panel-mounted SD access and a USB cable, but it's very doable.

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@TK. if you have time, would it be possible to define a requirements list of UI features (OLED real estate required, encoders, switches, 3.5mm eurorack input and output ports) that you would like to see in a new dedicated future MBCV module? :)

We were lately discussing/planning a new STM32F4 based digital oscillator eurorack module which may have quite similar UI requirements - that way we might get away with a single set of PCBs that could satisfy two usecases! :). 50mm max depth is a given.

Many greets and best regards!
Peter

 

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Must-have requirements:

  • STM32F407VG (1MB flash)
  • SCS with 6 buttons, 1 encoder and 1 GLCD (so that we can also use the display as a scope)
  • 1 MIDI IN, 1 MIDI OUT
  • USB Device
  • SD Card
  • SRIO (J8/9)
  • J19 for AOUT
  • 50mm depth
  • HP doesn't matter as long as it still fits into the Pod40X case together with the Expander modules

Optional:

  • up to 3 additional MIDI IN/OUT (could also be provided as an optional module)
  • USB Host
  • 4 on-board LEDs
  • Audio-DAC

Potential extension modules:

  • SRIO based encoder/ledring modules
  • AINSER64 module (with at least 8, but maybe 3x8 INs?) - inputs should be buffered, protected and maybe also amplified and level-shifted for +/- 5V

Such a module could also cover MBNG for script based processing.

Best Regards, Thorsten.

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