Weird power on behaviour of Duet2 wifi

Sazabi

Hey, everyone.

Having strange issue and I need your advice to get direction.
My duet2 wifi powers from 24V psu. It also connected to ssr, controlling that psu via PS_ON pin. I've added capacitor on ssr control pins, to keep it closed to be able to reset board from DWC. Without cap, board releases ssr and everything turns off. It was working great. I have 2 Z motors on Z driver and Z probe.
Now, I took off Z probe, switched one Z motor to second driver (E1), added 2 optical endstops, changed config. It works as expected except for one thing - on initial launch, board doesnt fully load. Paneldue doesnt show any info like it haven't connected to board, no led flashed on wifi module. Only endstop's leds and voltage leds(all 3) are on. Pressing reset button on board makes it run correctly.
Also, message on paneldue after reset shows "VIN overvoltage 32.6V", but psu is still the same and shows 24.2V (DWC shows 24.3-24.4).
What can be the reason for this?
Config attached.
config.g

dc42

@sazabi said in Weird power on behaviour of Duet2 wifi:

Also, message on paneldue after reset shows "VIN overvoltage 32.6V"

That suggests that something is pulling down the 3.3V rail during startup. How have you connected the capacitor and SSR to the Duet? What value capacitor did you use?

Sazabi

@dc42 just finished printing part. Rebooted board, dont have this message now, changed nothing.
Cap parallel to ssr control pads, I'd say connecting ps_on and 5V (my ssr doesnt work on 3.3v). Cap is huge, the only I had at hand - 2200uf 25v.

Sazabi

Ok, disconnected cap and now it starts fine. Where should I place it to make everything work as expected? Directly to board power input terminals?