Great minds etc
The board is this:
and the Nano comes from:
Curious about your remark regarding the 12v power - the write up suggests between 6 & 20vdc - but is the Nano actually powering anything else?
My servos are connected to the expansion module and their 5v comes from the control panel, likewise the indicator LEDs.
The Nano boards I have bought for testing are the ones in the link, I don't know the source of the ones on the railway yet.
The diode was added while testing the circuits prior to connecting the servos. [...]
I still don't know why because there is no reason for it as far as I can tell. But I have no idea what is on the expansion board. And it's still not 100% clear how you connected everything. Do you just supply power to that expansion board or do you really have external regulators?
So the only regulator is ON that expansion board?
And yes, maybe that 10k would also fix the glow. A modern LED doesn't need a lot. But again, expect from the pin floating, I see no reason for there to be any (real) voltage.
And what exactly does get hot? The regulator on the expansion? Or the regulator in the Nano? Or the Nano itself?If it's the first (because I assume* the expansion regulator supplies the servo), does it still happen when the servo's are disconnected?If it's the Nano, does it still happen with nothing connected? If so, just throw it in the bin
* But assumption the the mother of all fuckups... So without schematic I don't know for sure.
No, the one for the switches is on my control panel
Not a glow, bright LED, full 5vdc voltage
Most noticeable on the USB port on the Nano. And on that one no servos are connected yet.
You have my schematics and a photo.
I have no other info at this stage.
Way too late to change the LEDs, panels built, working and done. That's a closed issue.
The panel, switches & LEDs were there long before the Arduino and servos.
I understand. But you still need the pull down resistor (close to the Nano) and power it the right way, don't you? Needing that diode tells me something is off.If an Arduino gets hot with nothing connected => bin New Arduino's should work fine with CH340 driver
Like I said, my problem is the COM ports which is where we came in ;-)
The 10k resistor is actually connected to the edge connector on the expansion board (as is the diode) and it works a treat.
[...] but that was already cured by the diode.
The only way I could find to do that was to install the 10k resistor on the pin which prevents unpredictable state changes [...]
The 5vdc on the un-powered pin seems to be a function of the Nano - most of what I have read says 'undefined'.
What do you mean? If you don't set the function or state of a pin from code a pin defaults to an INPUT. And an input is high impedance, it can be any voltage. It's like a ball in a rally car aka all over the place.