Author Topic: seems to work, but no display  (Read 520 times)

northerntao

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seems to work, but no display
« on: January 16, 2017, 02:57:43 AM »
I finally build my PreenFM2 kit from Van Daal, and it appears to work, but I have no display.  The LEDs flash, and I get stereo sound from each of the 5 switches when I hold down the menu key.  Both USB and 9v + work.

All the voltages check out from the image on http://ixox.fr/forum/index.php?topic=63509.0.

I do have one question.  I have a 5c revision of the board in the kit from Van Daal.  For the OLED resistor, should it be 22, 68, or just a short?  The build documentation is a little confusing, as it says to use 22 in one place, and a resistor pin in another paragraph for the OLED screen, but the board is labeled 68.

I am pretty much a beginner solderer, but I'm fairly confident all my joints are solid.
« Last Edit: January 16, 2017, 02:59:23 AM by northerntao »

Xavier

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Re: seems to work, but no display
« Reply #1 on: January 16, 2017, 09:57:13 AM »
Yes, there's some confusion with the PCB revision.

The 68 ohm resistor (beside the 10k) is a resistor for the LCD led powering. So it's not used at all with the OLED displays.

The revision "5c" of the PCB does not have the "OLED" resistor. It will work fine. But the OLED hight pitch modification  is a bit more complicated to make with this revision.
Your OLED display should work fine, there's nothing special to do.
Please, post clear pictures of all the display solder points so that we can take a look.
« Last Edit: January 16, 2017, 11:43:30 PM by Xavier »

northerntao

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Re: seems to work, but no display
« Reply #2 on: January 17, 2017, 04:24:13 AM »
I reflowed the solder on the female display header on the PCB, as it looked a little rough.  Didn't seem to make a huge difference, but I could swear that I saw some yellow lines on the OLED on one of my attempts to boot it with the display attached.  I had the USB drive in at the time, but took it out for the photos.

northerntao

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Re: seems to work, but no display
« Reply #3 on: January 17, 2017, 04:24:47 AM »
Photo 2

northerntao

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Re: seems to work, but no display
« Reply #4 on: January 17, 2017, 04:25:14 AM »
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northerntao

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Re: seems to work, but no display
« Reply #5 on: January 17, 2017, 04:25:32 AM »
Photo 4

mmontag

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Re: seems to work, but no display
« Reply #6 on: January 17, 2017, 09:42:14 PM »
Heh, had this exact problem last night. No backlight. But it worked fine after I popped the 68 ohm in that empty spot. Thanks Xavier 👍
« Last Edit: January 21, 2017, 12:02:11 PM by mmontag »

northerntao

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Re: seems to work, but no display
« Reply #7 on: January 17, 2017, 10:28:55 PM »
I think I snipped the 68k off before I even turned it on!  I probably have another one laying around from another project so I'll put it back in there and see if that makes a difference.  Maybe it is just the backlight and I can't see the characters.

northerntao

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Re: seems to work, but no display
« Reply #8 on: January 18, 2017, 01:37:57 AM »
Shit, all I have sitting around are some ancient 51k and 15k resistors, which I tried adding in series to the slot, but it didn't work.  One of my next BOMs for another project, I'll have to add a 68k to that if this is indeed the problem.  Argghh!  So close. 

northerntao

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Re: seems to work, but no display
« Reply #9 on: January 18, 2017, 02:35:19 AM »
I found a 68k resistor (purloined from my Jasper BOM) and put it in there.  Same behavior.

I did short the pad with a resistor pin, so I didn't miss that.

Another thing I didn't mention, is that the kit I got came with the shield mod - a steel plate with some additional spacers.  It also came with a red wire, which the build instructions didn't address.  Am I supposed do do something with that wire?

UPDATE - Found the instructions for the wire.  "You have to cut the pin 2 of the OLED header then link pins 2 and 15... See the red wire on the picture above and the missing pin between the OLED and the preenfm PCB. I remove the whole pin but simply cutting it on the OLED side will work."

Doesn't help with the display.  :(  I don't want to have to order another kit or give up and buy an assembled one. 
« Last Edit: January 18, 2017, 03:02:24 AM by northerntao »

Xavier

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Re: seems to work, but no display
« Reply #10 on: January 19, 2017, 09:46:16 AM »
Hi,

Sorry for being late here.

You bought your kit from Van Dall Electornics : I think they ship only OLED so i assume you have a yellow OLED display.
Please confirm...

Reminder :
http://ixox.fr/preenfm2/build-it/thebuild/

I found a 68k resistor (purloined from my Jasper BOM) and put it in there.  Same behavior.

I assume you meant 68 and not 68k. I don't know where you saw 68k.
This 68 ohm resistor is for the LCD display  Anyway it cannot hurt with an OLED it's just not used.

Another thing I didn't mention, is that the kit I got came with the shield mod - a steel plate with some additional spacers.  It also came with a red wire, which the build instructions didn't address.  Am I supposed do do something with that wire?

This kit is provided by Van Daal Electronics, contact them for more info.
But this seems to be for the OPTIONAL mod.

UPDATE - Found the instructions for the wire.  "You have to cut the pin 2 of the OLED header then link pins 2 and 15... See the red wire on the picture above and the missing pin between the OLED and the preenfm PCB. I remove the whole pin but simply cutting it on the OLED side will work."
Doesn't help with the display.  :(  I don't want to have to order another kit or give up and buy an assembled one. 

This is an optional mod. Cannot fix anything if it didn't work before.
But NOW (if you cut 2 and linked pins 2 and 15) you must fill the 68 ohms which is redirected to the display power pin.
A 68 ohm will work (not a 68k), but a 22 ohm is better (brighter display).

I would check shortcuts between adjacent pins in the attached pictures.


Xavier
« Last Edit: January 19, 2017, 09:48:05 AM by Xavier »

northerntao

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Re: seems to work, but no display
« Reply #11 on: January 21, 2017, 08:29:12 AM »
Pretty certain it's a yellow OLED. I'm not sure how to tell the difference between the two without it being turned on. I did see some yellow squares very briefly at one point.

I don't know where I got 68k. Duh, but I've taken it out. I tried it with nothing, a resistor pin, and a 22 ohm, but no change.

I haven't cut any of the pins for the mod.

I'll check those pins. I may try removing the solder on the header and redo it.

Worse case, I'll try and find someone in the US that is more experienced than DIY electronics to look at it.

Thanks Xavier (and company)