Another OLED Audio Noise Question

Hi, I've got an arduino audio project that uses a 1.5 OLED I2C display. The display generates so much noise in the audio signal. As soon as I disconnect the OLED, the noise floor is so quiet, it's wonderful. The tone of the noise changes depending on what and how much is displayed on the screen.

I know there are a plethora of causes for these things ranging from lead dress, bad ground technique, decoupling caps, etc.

My question is, usually, to fix these types of issues, is it really a matter of using a scope, finding the offending frequency and it's origin (probe), and filtering that node with caps?

Or is there a golden rule of thumb, especially with grounding and separating my digital/analog, that I'm missing?

doxasound:
My question is, usually, to fix these types of issues, is it really a matter of using a scope, finding the offending frequency and it's origin (probe), and filtering that node with caps?

Does it not seem that you know exactly what is generating the noise - you say it is the OLED.

Start by putting a 10 µF electrolytic and a 0.1 µF ceramic directly across the OLED power pins.

Then look into the lead dress/ layout and grounding arrangements as you have cited.

More specific advice would require us to know what you are actually doing.

Paul__B:
Does it not seem that you know exactly what is generating the noise - you say it is the OLED.

I guess I was thinking there was noise coming right from the OLED's circuit. Like the charge pump. I was more wondering how people use a scope to find the issue.