dfu mode issue

[Toltekradiation]

hello,
i have been struggling with the preefm3 build for some time, due to a weird issue :
the dfu mode did not set up when i linked BootD and DFU pins : it seems that the DFU pin does not hold any voltage (on naked board, nothing plugged except usb )
Finally, i linked 3,3v with bootD and could then enter DFU mode and flash the firmware.
It start, the screen seems to work ok, but not the sd card (error #6)
And now, the control board does not act as it should : complete mismatch of buttons and actions.
the 5v pin on left of main board has no voltage as well, there may have some sort of short somewhere, but i can't figure out where  :
the soldering inspection did not give any result (joined two photos of the board, with some voltage values.)

surprisingly, I can play notes and even edit the patch with USB!

Any hints is appreciated...

[forestcaver]

Have you soldered the control board headers? It doesnt look like it from the photos...

[Toltekradiation]

yes, i have soldered the headers : only the needed pins, as described in the Vandaal electronics instructions :
https://vandaal-electronics.com/wp-content/uploads/2020/12/preenFM3-Assembly-instructions.pdf

i also triple checked all the headers : there is no shorts between pins..

[lokki]

It seems as though both the 5v and 3.3v lines are broken somewhere.
Strange. Can you measure the voltages on the main board again without the controlboard attached?

Bad sdcard could be a display pcb issue, did not work on mine either. I ended up soldering one of those sd to MicroSD adapters to the pins, that works reliably...

[Xavier]

Yes it looks like there's a problem on your 5v line (SD problem is likely different).

The 0.01v you have on the 5v is expected. It should not be labeled "5v" i changed that on recent PCB.
This is a bridge you have to solder if you want to power the "HP" (Auxiliary output on the left).

Your 2 x 3.29v are fine, that comes from the stm32 which is powered.

What is not working is the right "0" (2) of the controlboard connection. It should be 5v. That explains why the control board is not working correctly.
(And as it's wired to vcc DFU so you have 0v on DFU VCC also).

I added a trace of the 5V line on the attached  picture.

I may be wrong but i don't think that's a shortcut. I suspect a bad connection when the 5V line goes on the back side (the 3 dots on the picture).

Can you double check that there's not shortcut between the 2 right "0" (Gnd and 5v) of the controlboard) ? (turn off the power to check continuity).

And test a continuity between the 3 left 5v point (1/ HP,  3/ DFU, 2/ right "0") and right 5v (4, 5, 6, 7, 8 ) ?

The SD is likely something different. Can you share a picture of the TFT PCB ?

[Xavier]

Strange. Can you measure the voltages on the main board again without the controlboard attached?

+1

[Toltekradiation]

thanks guys, thanks Xavier,
we're getting closer to the solution !

i checked the voltages :
4,5,6,7 : 4.8v
1,2,3,8 : 0v

it seems that the 5v is lost after the (4).
Continuity is correct everywhere except between 4 and 8.
It's also correct on the control board.

maybe i should wire the hp hole (1) with +5v ?

About the sd card, i joined photos of the TFT.

[Xavier]

Continuity is correct everywhere except between 4 and 8.

 
Between 4 and 8
That's unexpected and really weird. That's a wide trace, i have no idea how that can happen...

maybe i should wire the hp hole (1) with +5v ?

Yes you can try that.
You can also try to resolder the point 4 (plus (+) of the capacitor), and maybe add a litlle solder ?

Your TFT/SD PCB is fine. That's not the bad one.
Error #-6# is a "no sd card" error.
Try to reformat the SD card with the official formatter : https://www.sdcard.org/downloads/formatter/
And copy back the /pfm3/ folder on it.

[Toltekradiation]

yes, that's weird, i tried to find any evidence around the broken zone and could not see anything. it may be broken under the capacitor..
so i made the 5v link and the control board work fine now,
but not the sd card reader : still error #6
i tried two sandisk : 1 ultra and another from the edge series, both previously formatted with the official formatter, deep formatting.
btw i use latest firmware.

i will have a look for another tft tomorrow.

[Xavier]

so i made the 5v link and the control board work fine now,

I think DFU and midi Din will also work much better.

but not the sd card reader : still error #6
i tried two sandisk : 1 ultra and another from the edge series, both previously formatted with the official formatter, deep formatting.
btw i use latest firmware.
i will have a look for another tft tomorrow.

I have this exact same TFT PCB and the SD card works fine.
Check the 4 pins soldering on the TFT PCB and the female one on the pfm3 main board.
I'll share a diagram with th 4 SD pins trace to check continuity.

[Toltekradiation]

then i checked the continuity of the sd traces : it were good until the sd socket itself, not so well soldered.
After resoldering the sd card socket, i now have a fully working preenfm3 

Thanks for the support, and for the preenfm3 ! i love it very much, the sequencer is funtastic and the filters sounds very nice in poly

[Xavier]

then i checked the continuity of the sd traces : it were good until the sd socket itself, not so well soldered.
After resoldering the sd card socket, i now have a fully working preenfm3 

Thanks for the support, and for the preenfm3 ! i love it very much, the sequencer is funtastic and the filters sounds very nice in poly

Nice !! 
Happy to see everything is solved !