PREENFM3 CONTROL PANEL CONNECTION PROBLEM

[odayan]

Hi,

Completely newbie here. Preenfm3 is my first DIY project.

I assembled everything as per the build but control board buttons and knobs were either not working or working randomly.

I thought this is because bad soldering, first tried to repair the suspected bad soldering and then tried to desolder 6 pin connector where I ruined some of the pads  :'(

At this point I took professional support and got the 3 ruined connections hardwired to the correct tracks. The unit returned to the initial build state where %99 of the time the buttons and knobs are not working.

I checked the forum treads with control board problems and followed the steps for checking.

I've done all continuity and shortcut tests on all the connector pins. All are ok.

I get 5v on all 4 74HC165

I've checked the continuity of all buttons, all are ok.

All led activity at the main board are ok.

Connecting a midi keyboard I get sound and midi activity but no blue light blinking on the control board.

I couldnt enter DFU mode with the DFU button, neither with the menu button (which is not working).

My control board version is V2.0.1 and the main board v2.1

Any advice on the next step?

Thanks!!!

Olus

[Xavier]

Hi,

Yes looks like some soldering problems.
If does not work 99% of the time, that means it works 1% of the time.

When you check the 5v on the 74HC165, where do you take the GND ? On the control board too ?
I ask this because it can be a problem with GND on the control board.

Or maybe a shortcut between the 3 Data pins between the control board and the main board.

The DFU built in button on the main board must be hold down when turning on the preenfm.
Then it enterrs CPU DFU mode, so the screen remains black. And DFU can be seen from a computer and a USB cable with a DFU capable software.

On the control board, the blue led will blink when the preenfm2 receves midi Clock from external midi.

Xavier

[odayan]

Hi,

Thank you for the comments.

If does not work 99% of the time, that means it works 1% of the time.

Sorry this was a bit misleading. I meant to say, it does nothing %99 of the time, and it works random %1 of the time. The unit starts at the mix section, very rarely the sound volumes change without touching anything. The only consistent button that I spotted is the seq button. When I press it sound 6 becomes active (yellow) but no parameter change. 

When you check the 5v on the 74HC165, where do you take the GND ? On the control board too ?
I ask this because it can be a problem with GND on the control board.

I checked it with the mainboard GND as well (GND pin right below the processor) and I get 5v. I checked the shortcut between the data pins both from the main board and the control board but all look ok.

Midi activity was there but without blue led blink.

I managed to flash the unit with DFUSE, the other web usb didnt work. However from the releases page the latest DFU file that I could find was for version v0.107. I also put this version on the SD card.

Strange things continue after that...

After flashing, no midi activity (neither blink nor activity on screen) and also the strange activity on the seq button is gone.

The unit started only a few times and control board did nothing. After that it did not start (no screen, no blue led activity on the main board)  :'(

Help please

EDIT: after another flash the unit started and blue led activity is normal. No midi activity and no control board function, no random activity neither.

[odayan]

Now reading this from another tread:

"New PCB (1.6-100) only works with firmware 1.09 and newer.
As written in firmware 1.09 : "With these new PCBs, the knobs and butons won't respond with earlier firmware."

Could you compile the DFU file for the latest firmware? Only Dfuse works for me.

Thank you!!!!

[Xavier]

Now reading this from another tread:

"New PCB (1.6-100) only works with firmware 0.109 and newer.
As written in firmware 0.109 : "With these new PCBs, the knobs and butons won't respond with earlier firmware."

Could you compile the DFU file for the latest firmware? Only Dfuse works for me.

Oh yes, i totally forgot about this possibility.
But all mainboard are shipped flashed with latest firmware, i don't know why you needed to flash it.
Anyway...
I only have a laptop where i am. Will try to create a DFU file.

[Xavier]

OK It was quick, i had the DFU generator on my laptop, but i cannot try the dfu file.
Let me know if the DFU file here works for you
https://github.com/Ixox/preenfm3/releases/tag/v1.00
Thanks

2 additional things :
. Puting the firmware on the SD card is useless. Only used if you want to flash it again.
. the blue led on the control board only blinks with Midi CLOCK input (not any other midi activity only CLOCK).

[odayan]

Thank you for the dfu and the additional comments!

I flashed the unit to the latest firmware with success and went back to the initial failed build state. The activity at the seq button came back.

But this time theres another issue... Sometimes the unit does not start immediately, waits for a few seconds, minutes and then it mostly starts (and sometimes not). This has never happened before.

I sent you the photos and video of the current state by wetransfer to the email preenfm1@gmail.com.

Thank you

[Xavier]

I had a look at the video/pictures.

The SEQ button things does not make any sens for the firmware.
So it's a hardware problem.
As if pushing the SEQ button sometimes allow the contact to be good.

The fact the sometimes the preenfm3 takes time to start can also mean that the GND can be wrong and the MCU (STM32) cannot get a clean clock that allows it to start.

Did you solder totally the control board to the main board ?
Would be interesting to see if you have the delay in starting when you turn on without the control board.

Xavier

Xavier

[odayan]

I think I found something!!!

Can you confirm that the LOAD goes to the 3rd pin of the processor from below left?? Theres no continuity from that to the LOAD pin of the main board.

Can you also confirm if the via right above the LOAD pin goes to the same pin of the LOAD at the processor? (3rd from left bottom). Theres no continuity on that via.

EDIT: theres continuity from chip to via, but no from via to LOAD pin.

The solder on the processor looks ok as well but this is the only problem that I found. Hope to have it spotted!!!

[odayan]

Yes it was LOAD connector and now works perfect!! After hours of headbanging that first crystal clear sound is priceless!!! 🕺😄

Everything works perfect, midi din as well, the only remaining issue is the midi clock light, all lfos arp and seq are set to ext and the unit receives clock (* blinks) but no blue led blinking (neither at startup)😄. What could be the problem?

[matrix12x]

You can check if the LED is in backwards.

[UltraBlack]

The straight edge of the LED should go towards negative. The rounded side towards positive

[odayan]

The straight edge of the LED should go towards negative. The rounded side towards positive

 

This is a surface mount LED that comes soldered with the unit. The LED used to light at startup and it is still working. I checked the continuity once more and it is ok from the processor to the LED.

At some point the LED blinked while playing the sequencer but later on I couldnt find how I did it. I think it was synced to the internal clock but I'm not sure.

As mentioned before, all works perfect other than the LED. LFO's, sequencer and ARP syncs well to the external clock.

[Xavier]

Yes it was LOAD connector and now works perfect!! After hours of headbanging that first crystal clear sound is priceless!!! 🕺😄

Everything works perfect, midi din as well, the only remaining issue is the midi clock light, all lfos arp and seq are set to ext and the unit receives clock (* blinks) but no blue led blinking (neither at startup)😄. What could be the problem?

I'm back home.
I'm so happy to read this  Congrats for the fix !!

So you're talking about the LED on the control board ?
It's a direct wire to the main board than to the CPU.
It's labelled simply "led" on both main board and control board.
But if everything else is working, i would NOT focus on that one, it's not very usefull !

[odayan]

Hi Xavier,

Yes it is working perfect! I've never had such a marvelous unit before, but as a beginner at fm, it is only giving me deep headaches these days 

I dont care about the LED itself, if you say that it is not a symptom of another problem that I dont know of, thats fine for me. Thank you!!!