Preenfm 3 - New build - Screen white

[TwistedGenetics]

Hi

I have built a PreenFM3, I have flashed it it in DFU mode but after switching jumper back it will only boot to a white screen?

I followed Van daal guid as I got it from him, the only difference I can see is he only soldered two pins where the two boards meat ( see picture ) but the guide on this site shows all pins soldered.

Kind Regards
Jamie

[TwistedGenetics]

It ok i sorted it

[TwistedGenetics]

I have a new bug now,

After a while the screen goes white, I can still hear and use the device but can’t see the screen.

Sometimes it comes back but fuzzy?

Any ideas

[Xavier]

I followed Van daal guid as I got it from him, the only difference I can see is he only soldered two pins where the two boards meat ( see picture ) but the guide on this site shows all pins soldered.

2 pins are OK. The rest are only copied on the top of the control board.

Glad you fixed the first problem. But what did you do ? that can help to solve the second one.

When the TFT goes white that means it receives corrupted info from the MCU.
That can be bad connection on the TFT solder points.
Try to resolder them.

When the screen goes white you can press MENU + "-". 
That reinits the TFT.

You can also in the menu set MENU>Config>TFT Reinit = Auto
The MCU will check every second if the TFT is OK, if not it reinits it. But if that happens to often, you have to fix the original problem.

Or try an other power supply, that can also happen if the power is very noisy.

[TwistedGenetics]

Hi Xavier

Thanks for the quick reply.

So after some head scratching the second problem is fixed. It’s somewhat related to the first problem  .

I followed Vandaals guide but there’s some stuff missing. So first problem was that I missed soldering the 3.5/5v header for on the TFT VCC. The second problem was the Jumper on this was a bit loose and and losing connection making the screen go funny. I pushed the pins apart a little to give the jumper a tight fit. Seems ok now for 40 mins.

Cheers
Jamie

[TwistedGenetics]

Ahh I spoke to soon...

It’s started doing it again?

+- do nothing to bring it back

[TwistedGenetics]

I think i have fixed it but time will tell....

I didn't want to unsolder the pins from the TFT as Vandall suggests in his guide so used header that i can plug the screen into. I think this was having a little movement until I  bolted the screen to the PCB with some spacers.

Seems ok for the time being.

[dtmr]

I have a similar issue. Also did the Van Daal build. Not a fan of their instructions with the TFT. Quite confusing since they leave you with spacers and headers they  doesn't mention in the instructions. Didn't use them because I tried rushing things, but I should have used them and read the instructions on github also.

The issue I have is that my screen stays black. I'll try resoldering all the solderjoints of the headers first.

I have the same black pcb as you, TwistedGenetics, and the holes for the headers on that pcb were really narrow. So narrow I couldn't fit the headers in, unless I had to force it and give it a few whacks.

[Xavier]

I think i have fixed it but time will tell....
...
Seems ok for the time being.

Finger crossed.

The issue I have is that my screen stays black. I'll try resoldering all the solderjoints of the headers first.

Stays black ?
That's a different problem.
That means the "Led" pins (TFT/pfm3 header) is not powered.
Can be one of the following easy to check things:
. the firmware is not flashed (check a blue led is on or flashing on the preenfm3 PCB near the MCU).
. the boo0 pins is not on "preenfm3" so it boots in DFU mode
. The "Led" pins on the TFT/pfm3 headers is badly sodered. check its voltage.

[TwistedGenetics]

Hi Xavier

Unfortunately it’s come back.

I have  resoldered  the TFT to the board now and it still happens. Sometimes after an hour sometimes with only after 5 mins?

What else do you think it could be? I tried a new SD card in it. I’m wondering if it caused from presets from my preenFM 2? Some presets also have user wavs in them which I transferred across also.

Also when I selected a user wave all the characters went a bit funny on the screen? Not sure if this helps?

I’m testing with just a newly created preset using only sin wav

Let’s see how this goes...

[Xavier]

No need to try to have reproducible steps.
That's not a firmware problem.

That's noise in the circuit, that corrupts data between preenfm3 and the TFT.

3 things you can do as written above.
I know the 2 first ones are just workaround but that can be worth trying, you didn't comment on them.

When the screen goes white you can press MENU and  "-".
That reinits the TFT.

You can also in the menu set MENU>Config>TFT Reinit = Auto
The MCU will check every second if the TFT is OK, if not it reinits it. But if that happens to often, you have to fix the original problem.

Or try an other power supply, that can also happen if the power is very noisy.

That can also be a faulty TFT which is why i like having the TFT in a female header.

[TwistedGenetics]

It hasn’t  happened in 2 hours when using presets made on the unit today as opposed to old presets, this is why I though it could be that

So doing the + and - didn’t do anything when it goes white, TFT reint auto doesn’t stop it. And I have used 2 power sources, a usb brick and a plug in extension power supply that also has usb power strip on it.

I have also included a picture of the corruption of the characters when using own wav, If a separate bug?

Cheers

[Xavier]

It hasn’t  happened in 2 hours when using presets made on the unit today as opposed to old presets, this is why I though it could be that

So doing the + and - didn’t do anything when it goes white, TFT reint auto doesn’t stop it. And I have used 2 power sources, a usb brick and a plug in extension power supply that also has usb power strip on it.

I have also included a picture of the corruption of the characters when using own wav, If a separate bug?

Cheers

OK thanks for the update.

MENU and '-' (not + and -). Hold menu down then press '-'.

Corrupted chars can happen when something is written outside the screen memory.
So yes different problem. And this one is a firmware problem
Can you share your wav ?

[dtmr]

Wow I didn't expect you to answer this quickly. With "black" I mean that it lits up, but no graphics, no color or white light. See picture 1 in the attachment

. the firmware is not flashed (check a blue led is on or flashing on the preenfm3 PCB near the MCU).

It was flashing when I booted it up with power over USB and pressing the red menu key.

. the boo0 pins is not on "preenfm3" so it boots in DFU mode

I knew this was a thing but nothing changed when I swapped the jumper's position and rebooted.

. The "Led" pins on the TFT/pfm3 headers is badly sodered. check its voltage.

That was my thought too. I reflowed every pin but to no avail.

When I had it boot up with the menu key pressed, buttons 2 and 3 did do some flicker on the screen and I heard the connect/disconnect sound on my PC (hooked up via usb cable)

Now I went ahead with desoldering the TFT before I read your response. I read some posts in this forum in the meantime and decided to try things out myself. I figured I wouldn't get a fitting reply so quickly, which is usually the case in DIY forums.

When I first assembled the TFT onto the main board, I noticed some wonky solderleg of the SD card-reader onto the pcb. I soldered the TFT in anyways the first time. Then I thought after not getting any visual feedback; desolder the TFT again because it's likely due to the SD card not being read properly because of the damaged solder joint of the SD cardreader. Other reason I decided to desolder, is to install the headers now because this would be better in the future for repairs and overall fitting. During first assembly I did a bad job by not using any headers between both pcb's so detaching the TFT would be very difficult, which I experienced today. Long story short,  the TFT is disassembled now.

You think that leg on the right of the sd-cardreader might be the issue? (see picture 2 of attachment)

[Xavier]

OK so the TFT leds are on.
That's an important detail because the leds are turned on by the firmware or bootloader, so it's running.
I assume you even have sound on output 1/2 if you play midi notes on channel 1.

When I had it boot up with the menu key pressed, buttons 2 and 3 did do some flicker on the screen and I heard the connect/disconnect sound on my PC (hooked up via usb cable)

It's because the bootlader is working:
. button 2 : enter DFU mode
. Button 3 : enter SD card access
So the USB communication change and your PC makes a sound.
It's flickering on button 2 bucause it turns off the display.

...
When I first assembled the TFT onto the main board, I noticed some wonky solderleg of the SD card-reader onto the pcb. I soldered the TFT in anyways the first time. Then I thought after not getting any visual feedback; desolder the TFT again because it's likely due to the SD card not being read properly because of the damaged solder joint of the SD cardreader. Other reason I decided to desolder, is to install the headers now because this would be better in the future for repairs and overall fitting. During first assembly I did a bad job by not using any headers between both pcb's so detaching the TFT would be very difficult, which I experienced today. Long story short,  the TFT is disassembled now.

You think that leg on the right of the sd-cardreader might be the issue? (see picture 2 of attachment)

The 4 pins are for the SD card only, and cannot impact in any way the display.
If there's a problem with the 4 pins, the SD card won't work but the display will work.

Can you upload good quality pictures of the STM32, so that i can check there's no short-circuit between pins that talks to the TFT.
And you can also double check with a multimetter there's not short between 2 adjacent pins on the TFT ?