Display knob will not change menu

I'll try this in a more general topic. I have a Folgertech 2020 and had an issue with the RAMPS board. That issue caused a fuse to blow on the power supply. I've replaced the power supply with a new one, new RAMPS board, and new 12864 display and when I press the know, it will beep and change to the menu, but turning the know will not change the menus or allow you to select anything. I've swapped various hardware around since I have several of each as spares, but can't get it to work. I've got new parts coming on Monday, but would like to know if the knob is controlled by the RAMPS board or the Mega.

Anyone know?

nothing is "controlled" by the ramps... consider the ramps as a interface layer, connecting the physical world to the mega

In the case of the knob, its wired threw the ramps directly to the mega io pins.

Quote
Dust
nothing is "controlled" by the ramps... consider the ramps as a interface layer, connecting the physical world to the mega

In the case of the knob, its wired threw the ramps directly to the mega io pins.

So any idea as to what could be causing it to not work?

dead mega io pins
miss configured firmware
bad connector on the ramps
bad soldering on the ramps
bad soldering on the mega
broken copper traces on the ramps
broken copper traces on the mega
ramps not fully seated on the mega
broken knob

lots to check...

the knob is really two devices in one, a switch activated by pushing the knob in and a rotary encoder
If you take a look at [reprap.org] at the bottom left is a device BC111E5244B2 this is is the switch/encoder

from gnd to btn-en1 and gnd btn-en2 it send out the encoder signals
A and B in this image


You need to put a multimeter on gnd and continuity on btn-en1 and slowly spin the knob, does the meter change from open to closed over and over?
then test put a multimeter on gnd and continuity on btn-en2 and slowly spin the knob, does the meter change from open to closed over and over?
If these two tests pass then the actual encoder is working.

pins_ramps.h tell me

#if ENABLED(REPRAP_DISCOUNT_SMART_CONTROLLER)
#define BEEPER_PIN 37

#define BTN_EN1 31
#define BTN_EN2 33
#define BTN_ENC 35

so its connected to pins 31 and 33

so check continuity from the btn-en1 threw to pin 31 (or 33) on the ramps and check continuity from btn-en2 threw to pin 33 (or 31)

If that all looks good, maybe your firmware is miss configured.

You have thermistors connected? Both of them?
Marlin will "lock up" when temperatures are out of set range.

hi,

i had a same problem as author and your comment helped. seems like BTN_EN1 is fried, constantly connected to the ground.

found a identically looking replacement from some arduino learning kit, gonna try to exchange it.

thanks