Vishay OLED brightness

[ym2612]

Hi all,

I'm building a PreenFM2 and I chose a Vishay OLED from Mouser for its white text display. https://www.mouser.com/search/ProductDetail.aspx?r=78-020N004AWPP5N0000

It works, and text is visible, but it's quite dim compared to photos I've seen of the yellow OLED. I soldered a jumper for the OLED resistor and verified that 5V is being delivered to the display (which is what the supply voltage is rated at). Is there a modification I can make to increase the brightness of the display?

FWIW, so far I hear no extra noise.

[ym2612]

Also, I should mention that the Vishay display is slightly too thick to fit behind the acrylic screen protector included with the metal case.

[Xavier]

Thanks for the feedback about this display.
A jumper for the OLED resistor was the way to go if your display is not bright enough.
I don't think there is other thing you can do.

Do you have a picture of it ? that reflects the brightness you see.

For the noise, you have to put a spectrum analyser (http://www.voxengo.com/product/span/) to be sure it does not add any noise at any frequency. Most of us don't hear the 13.5Khz peak of the yellow display.
Would be great to view what is the spectrum of you audio output with the preenfm2 switched on.

Xavier

[ym2612]

Sorry for the delay on these images. I took screenshots in a spectral analyzer for iPad.

Vishay display (clickable image):


Yellow OLED (no shield):


Yellow OLED (homebrew aluminum foil shield):


As you can see, the noise spike is still very present and audible even with the shield I made, so hopefully I can make another display work or fabricate a better shield.

[ym2612]

Here are some photos of the Vishay display plugged in:

[Xavier]

Thanks a lot for the screenshots. 
That's very usefull and interesting.

All people who were annoyed by the high frequency peak reported it's not audible anymore after the shield + OLED resistor modification.
If you haven't done it before, look at the spectrum while trying to find the best place for your shield. 5mm can make a difference.
Also, verify what you hear is not directly the display (put the preenfm2 far away from you) and not a peak in the audio. (That happened to someone);.

I've just ordered a white and a green OLED display (Raystar). I'll report what result i got from them.

[Xavier]

The white Raystar i just received is also much darker than the other colors.
Its brightness is very sensitive to voltage. You need a strong 5V.
I quite like anyway it and it's very quiet

The green one is very nice but same nois as the yellow one.

[ym2612]

I switched my yellow OLED back to the white Vishay. It's dimmer, but I prefer the lack of noise.    I'll just avoid pointing a work lamp directly at it.

[solipsvs]

so is there a resistor that can be changed so this display is as bright as other colors?

[Xavier]

so is there a resistor that can be changed so this display is as bright as other colors?

No, white oleds are much less bright.

[solipsvs]

my tech has them in his tx802 and tx81z at full brightness and was looking to try to find where the limiting resistor that is on the rev c pfm2 PCB...   there isnt one?

[Xavier]

my tech has them in his tx802 and tx81z at full brightness and was looking to try to find where the limiting resistor that is on the rev c pfm2 PCB...   there isnt one?

What limiting resistor are you talking about ? I don't get it.

A small update : I put today a 2x40 white oled in my ambika and it works great.

I have no idea what the problem is with th 4x20 white OLD in the preenfm2. I'll update this thread if i find something.

[solipsvs]

thanks man, not trying to be a pain.  my white euro rack adaption just wouldnt be complete without a white oled.  pfm2 is a very nice looking synth if you ask me.  white display would make it more so