7i73 LCD shows rubisch

Did you try with 3.3V power?
If the display has CMOS level inputs (as opposed to TTL level)
3.3V signals and 5V power would be marginal

In my first message, I attached a link from the documentation
" voltage from 3.3 V to 5 V ". The test under arduino is with 5 V
it must not come from there

Are the Arduino signals 5V or 3.3V? (7I73 are 3.3V)

I just watched on the arduino (pro micro leonardo)
empty : 4.6 V
with load display LCD: 4.1 V
with load display OLED: 3.6 V !!!

it's not 5 V hum hum ...

I'm going to order one of the OLED displays and see If I can duplicate/fix the issue, but it will be a week or two...

Note that going by display specifications, it would not be expected to work with
5V VDD and the 7I73s 3.3V logic levels
(display spec for logic high is 80% of VDD = 4V with 5V VDD)

I will order a display that will work at both 5V and 3.3V to check this out

Hello to both of you
Andy no jumper for the 3.3 V a link for the
detailed documentation is attached to my first message
oled plugged into the 7i73 the voltage is 4.95V

Thank you PCW, it's not urgent, it's the beginning of a retrofit

I thought at the logical level, but I did not know that the logic level of the 7i73 was 3.3 !!
I will try quickly connect the oled on the 3.3V (P2 pin 29)
thank you,
I will keep you informed

" the devil is in the details "

Yes it was a logical problem

Remains pollution by a blinking cursor (1 Hz) ?
the cursor appears immediately on the power on (up left 0,0)