Author Topic: PreenFm2 wont start and display problems  (Read 392 times)

IvanoFM

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PreenFm2 wont start and display problems
« on: March 14, 2019, 09:38:30 AM »
Hi all,

thank you for accepting me on this forum, I'm glad to join preenFM community =)

So I've finished my build of preenFm2 kit, I bought it on TubeOhm.
I connect it via usb to pc, and seems working fine display is functiong, buttons and encoders work and my pc even recognize preen fm2 as connected device.

After that all seems working fine, i turn it off, to build the case around it and finish the build. But now as I connect it again to the pc not only my pc wont recognize it as device but preenfm2 screen is black. The 4leds flash rapidly then display remain black.
Not knowing what to do and that Jmp3 might be a problem, i try to connected the 2 jmp3 pins together, note that before this action they where not connected for the whole time, as if I'm correct should be, and turn it on again. Then remove the connection from 2 jmp3 pin and try again, nothing screen black again.
I thought it was a display problem, so I disconnected it checked the header for pin shortage, but was all good, and connected it again and then turn on the preenfm2.
Seems to work, the display is lit and I can navigate menu. But then as I was trying to load a bank by pressing menu button, the writing on the display become all strange and unreadable(strange symbols/or partially readable letters).
Turn it off and on again, menu fine try to navigate same thing happens. Turn it off and on again this time black display...This thing repeat randomly each time i turn it on. I also seem to hear a high pitch noise when I connect the audio jack to headphones or speakers, that is display noise problem I read somewhere, am I right?

What's happening to my build? I was so happy that it seemed to work on first try =(

Thank you in advance for helping me

Ivano
« Last Edit: March 14, 2019, 09:40:37 AM by IvanoFM »

Xavier

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Re: PreenFm2 wont start and display problems
« Reply #1 on: March 14, 2019, 10:04:06 AM »
Hi Ivano,

First jmp3 is only usefull if you want to flash the bootloader, so you don't need it. Should be open all the time.

What display did you have with yout kit ? OLED ? LCD ?
Is the "oled" resistor soldered ?

If it worked again after you unplug and plug back you display the problem seems to be here.
Resolder the display header on both the PCB and the display... double check there's no shorcut between adjacent pins.
Resolder the 40 pins socket of the preenf405. Also check for shortcut betwen points.
Make sure the preenf405 is well inserted.

Xavier

IvanoFM

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Re: PreenFm2 wont start and display problems
« Reply #2 on: March 14, 2019, 11:12:43 AM »
Hi Xavier,

thank you for answering. I have the oled display, but actually didnt solder the resistor named oled on pcb, because the pcb had the write oled = 0, 22 oled mod. So do I have to solder the 22ohm resistor then?
Also I will resolder the headers on display, pcb and on preenf405, but to be honest the soldering points were clean and shiny on all three with no shortage beetween pins.
What I had problem with was to actually fit the preen405 in the socket, it was hard to fit, i gently forced into it, so maybe it has some back contact?
I have not heard any sound from preenfm2, is there a way to test it without having to connect a midi keyboard?
I have instead hear a high pitch noise when connecting audio jack to headphones or speakers. Is there a way to fix that?
Another thing is that when display is working sometimes, when u navigate menu it suddendly reduce its brightness, then if press some other buttons it comes back, what is doing this?
Thank you for your cooperation, I'll work on it as soon as I can, so I can give you feeback about it and we can work out a solution together =)

Ivano

Xavier

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Re: PreenFm2 wont start and display problems
« Reply #3 on: March 14, 2019, 11:39:38 AM »
I know the info on the PCB are not clear at all, but it's quite clear in the build doc  ;)
"f you have a PCB revision R5d, you’ll have an additional resistor named Oled on the right of the above picture .
Populate it with a 22 ohm if you have an OLED display or shortcut it with a resistor pin if you have a LCD display."

So With a oled display the "oled" resistor must have a 22 ohm resistor. This provide the main power of the display.

For the high pitch noise of yellow oled display :
http://ixox.fr/forum/index.php?topic=69159.0

Xavier

IvanoFM

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Re: PreenFm2 wont start and display problems
« Reply #4 on: March 18, 2019, 07:25:39 AM »
Hi Xavier,

my preenfm seem to work fine now, the problem were display connection(header). So to avoid that problem maybe in the future, wouldn't it be more easy to instead solder a strip of wires?I mean like bus parallel wires, it makes the connection less solid like the header, but more flexible. What do you think about it?
Also I'd like to use my preen with a power supply, but I didn't find or probably missed the informations about the polarity of the dc connector and the specifics of it. Can you provide me those informations?
Thank you

Ivano

Xavier

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Re: PreenFm2 wont start and display problems
« Reply #5 on: March 18, 2019, 10:03:18 AM »

Glad to read it's now working.
The power supply needed is a regular 7.5v or 9v ground outside.

Xavier