[solved] preenFM2 DIY-Kit: dark display / not booting / no usb-connection

[thx1138]

Hello and greetings!

I ordered a kit from TubeOhm and happily began soldering. I'm by no means a pro nor very experienced. It's quite possible, that i did one or more blunders while putting it together. However, i double checked the solderings and i'm at a loss for what to do next.

The usual data:

PCB: Rev 6.2 - 10/2020
OLED-Shield: https://www.raystar-optronics.com/oled-character-display-module/20x4-oled-display.html

USB-Stick: Intenso Micro Line 4GB @Fat32
Stick-Contents: please see the attached screenshots

Further symptoms:

I powered it via USB, the little 3,3v LED lightens up and i can hear a power "click" on the lineout while (de)powering the unit as well as some hissing (Jumper default/0 Ohm) and way less hissing (Jumper at 22 Ohm). The internal type A USB-Port was measured at 5V. It completely fails to register as a USB-Device of any kind (midi, filesystem, dfu-device) in Windows.

I can provide some high-detail-photos, if necessary.

Any help would be greatly aprecciated.

thx1138

[forestcaver]

Did you set the boot jumper before trying to flash the bootlosder? How are you trying to flash it? I had no joy via a browser and used the dfu toolset... (I also have several stlinks so that is a possibility)

[thx1138]

Did you set the boot jumper before trying to flash the bootlosder? How are you trying to flash it? I had no joy via a browser and used the dfu toolset... (I also have several stlinks so that is a possibility)

Ah, yes, i shortened the boot-jumper and powered the device on, as described on this page. However, both the browser-tool and DfuSe couldn't see the device. At this point, i didn't bother to try any CLI-tools.

[Xavier]

Hi and welcome,

So you don't see any blue led when turning on the preenfm2 - it should be on 1 second then blinking every 2 seconds ?
If not, you have  to flash the bootloader and firmware.
Before that "darkdisplay  and no usb-connection" is totally expected.

Try again and give details about where it fails.

[thx1138]

Alright, i managed to flash the synth. Some useful links, because Windows 10 threw a mean curve ball while i tried to flash the pfm2:

(1) https://www.youtube.com/watch?v=AeaglOYphfc
(2) https://zadig.akeo.ie
(3) https://www.hanselman.com/blog/how-to-fix-dfuutil-stm-winusb-zadig-bootloaders-and-other-firmware-flashing-issues-on-windows
(4) http://dfu-util.sourceforge.net/releases/

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The Preenfm is now up and running (including the display), but i can't hear anything. Not startup-jingle and not played notes. It does receive midi via USB on all 4 channels.

Bootloader is 1.13.
For the firmware i tried both 2.20 and 2.20_cv.

[Xavier]

Thanks for the link.

The Preenfm is now up and running (including the display), but i can't hear anything. Not startup-jingle and not played notes. It does receive midi via USB on all 4 channels.

Number of voices for the instrument is different from 0 ?
The volume pot is in in place and soldered ?
Sure you flashed 2.20 and not 2.12 ? you need 2.20 with the new PCB.
You see "24 bits DAC" at the bottom of the boot screen ?

Bootloader is 1.13.
For the firmware i tried both 2.20 and 2.20_cv.

2.20 is the one you need.
"cv" is control voltage for the Eurorack version.

[thx1138]

Number of voices for the instrument is different from 0 ?

Yes.

The volume pot is in in place and soldered ?

Yes.

Sure you flashed 2.20 and not 2.12 ? you need 2.20 with the new PCB.

Yes, i used the latest release from here.

You see "24 bits DAC" at the bottom of the boot screen ?

Yes.

Bootloader is 1.13.
For the firmware i tried both 2.20 and 2.20_cv.

2.20 is the one you need.
"cv" is control voltage for the Eurorack version.

I reverted the Firmware back to the non-cv 2.20.

[Xavier]

The volume pot is in in place and soldered ?

Yes.

And turned up ?

When you say it receives midi, you see the number 1-4 on the display with midi activity ?

Have you tried holding down MENU and pressing one of the 5 left buttons. It should make a note with a note icon on the screen ?

If nothing work,  please post a high quality pictures of  your PCBs both side. Thanks.

[thx1138]

And turned up ?

When you say it receives midi, you see the number 1-4 on the display with midi activity ?

Have you tried holding down MENU and pressing one of the 5 left buttons. It should make a note with a note icon on the screen ?

I tried your suggestions and the display showed it acordingly, but the audio is still dead. I'll send you a PM with pictures.

[thx1138]

On a whim, i replaced the USB-stick packaged with the DIY-Kit with an older one, reflashed 2.20 just to be on the safe side and guess what: the whole thing works now.

Thank you very much for your support!

[Xavier]

OH nice...
Thanks for the update.