Led Brightness - Trim pot turns endlessly?

Exactly how long am I supposed to turn the R21 trimpot counter clockwise?

In the assembly instructions it says “until the end”, well, I have been turning it for 10 minutes, and there is still no resistance?

Is the trim pot broken?

There is no “end”, you will hear a faint click and maybe you can feel it clickin… but you can turn it till the sun is out of nuclear fuel…

edit: If you had read the instructions for the Filter Board till the end you’d discovered this:

"Some general notes regarding trimming:

Trimmers are 22 turns. Once you’ve reach one of the extremities of their range, you’ll still be able to turn the screw but it won’t have any effect. You’ll hear a small click or notice a slight change in torque required to turn the screw."

Thanks for your quick reply, however, whatever I do, the display stays bright and blue, no characters are readable, I don’t know how to proceed. Any tips?

The trimmer adjusts the contrast, not the LED brightness. There should be a position in which the characters appear on the LCD. If it doesn’t, the contrast trimmer is badly soldered.

I am pretty sure that the R21 trimmer is soldered correctly. Everything seems to work, but i can not seem to adjust the contrast of the display! I tried eveery which way possible…

What else can I try?

What is the voltage at the middle pin of the contrast trimmer? I have 1.3V here.

Most supiciously its the GND Pad from the trimmer (the one pointing to the ATMega) … I’m 80% right with this… resolder it!

I’m everytime shure i soldered correctly till the moment the machine works when i resolder the pad…

I have 5V at the middle pin…I will resolder the gnd pin, again…

Yeah! If it doesnt work try a piece of wire to some other GND Pad…

Or try turning the trimmer for 24 turns in the other direction!

Lol, pichenettes, that did the trick! Thanks so much for your help, it is very much appreciated