Author Topic: pfm2 with yellow OLED : high frequency solution  (Read 23312 times)

SMF

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Re: Yellow OLED : high frequency solution
« Reply #45 on: April 08, 2020, 02:12:00 PM »
My version (R5d) has the OLED mod applied (22 Ohm Resistor), it even has this marked on the PCB ("OLED = 0 or 22 for OLED MOD")... and there is a (grounded) shield in between the OLED-Board and the Preen-Mainboard. But still I have a significant(!) amount of this high pitched tone in my recordings (-60dBFS is not really near being acceptable for me)...

Any suggestions?

SMF

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Re: Yellow OLED : high frequency solution
« Reply #46 on: April 08, 2020, 06:16:50 PM »
Additionally to the thick, single layer grounded aluminium-shield which was already inside my preen, I dersperately added 216 Layers of aluminium-foil like discribed in the initial post by Xavier. This was just the maximum I could snuggly fit in between OLED-Module and Preen-Mainboard. These layers are not connected to anything and remove ANY(!) spurs I still had in the output.

I can measure down to -120dBFS and there is plainly nothing left. So, to me it seems like all spurs I had were related to the OLED-Module. It also seems to be just the magnetic field produced by the Buck-converter (PSU) on the module. Most probably (but I don't have a need to give this a test-run for now) ferromagnetic material (multiple thin iron-sheets) would be better suggestion for a shield against the magnetic field than using aluminium.

Stefan

dimifrag

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Re: Yellow OLED : high frequency solution
« Reply #47 on: April 12, 2020, 02:01:43 PM »
with the r4 pcb you have different solution?

cokosha

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Re: Yellow OLED : high frequency solution
« Reply #48 on: October 12, 2020, 10:07:34 AM »
Hello, Xavier!
does a new board preenfm2 R6 SMD need a protective shield?

Xavier

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Re: Yellow OLED : high frequency solution
« Reply #49 on: October 12, 2020, 11:52:02 AM »
Hello, Xavier!
does a new board preenfm2 R6 SMD need a protective shield?

Hi,
Short answer : yes

From my test the yellow oled noise is a bit lower.
As you can see on the PCB R6 there's nothing bellow the guilty yellow OLED coil, but that was not enough.

You can still go with this blue OLED :
https://www.tme.eu/en/details/rec002004abpp5n0/alphanumeric-oled-displays/raystar-optronics/rec002004abpp5n00000/
Or any LCD if your case allows that.